Add m-esr52 at 52.6.0

106 files changed, 30515 insertions, 0 deletions

diff --git a/xpcom/glue/AppData.cpp b/xpcom/glue/AppData.cpp
new file mode 100644
index 0000000000..845267e60d
--- /dev/null
+++ b/xpcom/glue/AppData.cpp
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/AppData.h"
+#include "nsXULAppAPI.h"
+#include "nsINIParser.h"
+#include "nsIFile.h"
+#include "nsCRTGlue.h"
+#include "nsAutoPtr.h"
+
+namespace mozilla {
+
+void
+SetAllocatedString(const char*& aStr, const char* aNewValue)
+{
+  NS_Free(const_cast<char*>(aStr));
+  if (aNewValue) {
+    aStr = NS_strdup(aNewValue);
+  } else {
+    aStr = nullptr;
+  }
+}
+
+void
+SetAllocatedString(const char*& aStr, const nsACString& aNewValue)
+{
+  NS_Free(const_cast<char*>(aStr));
+  if (aNewValue.IsEmpty()) {
+    aStr = nullptr;
+  } else {
+    aStr = ToNewCString(aNewValue);
+  }
+}
+
+ScopedAppData::ScopedAppData(const nsXREAppData* aAppData)
+{
+  Zero();
+
+  this->size = aAppData->size;
+
+  SetAllocatedString(this->vendor, aAppData->vendor);
+  SetAllocatedString(this->name, aAppData->name);
+  SetAllocatedString(this->remotingName, aAppData->remotingName);
+  SetAllocatedString(this->version, aAppData->version);
+  SetAllocatedString(this->buildID, aAppData->buildID);
+  SetAllocatedString(this->ID, aAppData->ID);
+  SetAllocatedString(this->copyright, aAppData->copyright);
+  SetAllocatedString(this->profile, aAppData->profile);
+  SetStrongPtr(this->directory, aAppData->directory);
+  this->flags = aAppData->flags;
+
+  if (aAppData->size > offsetof(nsXREAppData, xreDirectory)) {
+    SetStrongPtr(this->xreDirectory, aAppData->xreDirectory);
+    SetAllocatedString(this->minVersion, aAppData->minVersion);
+    SetAllocatedString(this->maxVersion, aAppData->maxVersion);
+  }
+
+  if (aAppData->size > offsetof(nsXREAppData, crashReporterURL)) {
+    SetAllocatedString(this->crashReporterURL, aAppData->crashReporterURL);
+  }
+
+  if (aAppData->size > offsetof(nsXREAppData, UAName)) {
+    SetAllocatedString(this->UAName, aAppData->UAName);
+  }
+
+#if defined(XP_WIN) && defined(MOZ_SANDBOX)
+  sandboxBrokerServices = aAppData->sandboxBrokerServices;
+#endif
+}
+
+ScopedAppData::~ScopedAppData()
+{
+  SetAllocatedString(this->vendor, nullptr);
+  SetAllocatedString(this->name, nullptr);
+  SetAllocatedString(this->remotingName, nullptr);
+  SetAllocatedString(this->version, nullptr);
+  SetAllocatedString(this->buildID, nullptr);
+  SetAllocatedString(this->ID, nullptr);
+  SetAllocatedString(this->copyright, nullptr);
+  SetAllocatedString(this->profile, nullptr);
+
+  NS_IF_RELEASE(this->directory);
+
+  SetStrongPtr(this->xreDirectory, (nsIFile*)nullptr);
+  SetAllocatedString(this->minVersion, nullptr);
+  SetAllocatedString(this->maxVersion, nullptr);
+
+  SetAllocatedString(this->crashReporterURL, nullptr);
+  SetAllocatedString(this->UAName, nullptr);
+}
+
+} // namespace mozilla
diff --git a/xpcom/glue/AppData.h b/xpcom/glue/AppData.h
new file mode 100644
index 0000000000..0134df32ca
--- /dev/null
+++ b/xpcom/glue/AppData.h
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_AppData_h
+#define mozilla_AppData_h
+
+#include "nsXREAppData.h"
+#include "nscore.h"
+#include "nsStringGlue.h"
+#include "nsISupportsUtils.h"
+
+namespace mozilla {
+
+// Like nsXREAppData, but releases all strong refs/allocated memory
+// in the destructor.
+class ScopedAppData : public nsXREAppData
+{
+public:
+  ScopedAppData()
+  {
+    Zero();
+    this->size = sizeof(*this);
+  }
+
+  explicit ScopedAppData(const nsXREAppData* aAppData);
+
+  void Zero() { memset(this, 0, sizeof(*this)); }
+
+  ~ScopedAppData();
+};
+
+/**
+ * Given |aStr| is holding a string allocated with NS_Alloc, or null:
+ * replace the value in |aStr| with a new value.
+ *
+ * @param aNewValue Null is permitted. The string is cloned with NS_strdup.
+ */
+void SetAllocatedString(const char*& aStr, const char* aNewValue);
+
+/**
+ * Given "str" is holding a string allocated with NS_Alloc, or null:
+ * replace the value in "str" with a new value.
+ *
+ * @param aNewValue If |aNewValue| is the empty string, |aStr| will be set
+ *                  to null.
+ */
+void SetAllocatedString(const char*& aStr, const nsACString& aNewValue);
+
+template<class T>
+void
+SetStrongPtr(T*& aPtr, T* aNewValue)
+{
+  NS_IF_RELEASE(aPtr);
+  aPtr = aNewValue;
+  NS_IF_ADDREF(aPtr);
+}
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/glue/AutoRestore.h b/xpcom/glue/AutoRestore.h
new file mode 100644
index 0000000000..20909c92c3
--- /dev/null
+++ b/xpcom/glue/AutoRestore.h
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* functions for restoring saved values at the end of a C++ scope */
+
+#ifndef mozilla_AutoRestore_h_
+#define mozilla_AutoRestore_h_
+
+#include "mozilla/Attributes.h" // MOZ_STACK_CLASS
+#include "mozilla/GuardObjects.h"
+
+namespace mozilla {
+
+/**
+ * Save the current value of a variable and restore it when the object
+ * goes out of scope.  For example:
+ *   {
+ *     AutoRestore<bool> savePainting(mIsPainting);
+ *     mIsPainting = true;
+ *
+ *     // ... your code here ...
+ *
+ *     // mIsPainting is reset to its old value at the end of this block
+ *   }
+ */
+template<class T>
+class MOZ_RAII AutoRestore
+{
+private:
+  T& mLocation;
+  T mValue;
+  MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+public:
+  explicit AutoRestore(T& aValue MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+    : mLocation(aValue)
+    , mValue(aValue)
+  {
+    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+  }
+  ~AutoRestore()
+  {
+    mLocation = mValue;
+  }
+  T SavedValue() const
+  {
+    return mValue;
+  }
+};
+
+} // namespace mozilla
+
+#endif /* !defined(mozilla_AutoRestore_h_) */
diff --git a/xpcom/glue/BlockingResourceBase.cpp b/xpcom/glue/BlockingResourceBase.cpp
new file mode 100644
index 0000000000..ada02c72ce
--- /dev/null
+++ b/xpcom/glue/BlockingResourceBase.cpp
@@ -0,0 +1,511 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/BlockingResourceBase.h"
+
+#ifdef DEBUG
+#include "prthread.h"
+
+#include "nsAutoPtr.h"
+
+#ifndef MOZ_CALLSTACK_DISABLED
+#include "CodeAddressService.h"
+#include "nsHashKeys.h"
+#include "mozilla/StackWalk.h"
+#include "nsTHashtable.h"
+#endif
+
+#include "mozilla/CondVar.h"
+#include "mozilla/DeadlockDetector.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "mozilla/Mutex.h"
+
+#if defined(MOZILLA_INTERNAL_API)
+#include "GeckoProfiler.h"
+#endif //MOZILLA_INTERNAL_API
+
+#endif // ifdef DEBUG
+
+namespace mozilla {
+//
+// BlockingResourceBase implementation
+//
+
+// static members
+const char* const BlockingResourceBase::kResourceTypeName[] = {
+  // needs to be kept in sync with BlockingResourceType
+  "Mutex", "ReentrantMonitor", "CondVar"
+};
+
+#ifdef DEBUG
+
+PRCallOnceType BlockingResourceBase::sCallOnce;
+unsigned BlockingResourceBase::sResourceAcqnChainFrontTPI = (unsigned)-1;
+BlockingResourceBase::DDT* BlockingResourceBase::sDeadlockDetector;
+
+
+void
+BlockingResourceBase::StackWalkCallback(uint32_t aFrameNumber, void* aPc,
+                                        void* aSp, void* aClosure)
+{
+#ifndef MOZ_CALLSTACK_DISABLED
+  AcquisitionState* state = (AcquisitionState*)aClosure;
+  state->AppendElement(aPc);
+#endif
+}
+
+void
+BlockingResourceBase::GetStackTrace(AcquisitionState& aState)
+{
+#ifndef MOZ_CALLSTACK_DISABLED
+  // Skip this function and the calling function.
+  const uint32_t kSkipFrames = 2;
+
+  aState.Clear();
+
+  // NB: Ignore the return value, there's nothing useful we can do if this
+  //     this fails.
+  MozStackWalk(StackWalkCallback, kSkipFrames, 24, &aState, 0, nullptr);
+#endif
+}
+
+/**
+ * PrintCycle
+ * Append to |aOut| detailed information about the circular
+ * dependency in |aCycle|.  Returns true if it *appears* that this
+ * cycle may represent an imminent deadlock, but this is merely a
+ * heuristic; the value returned may be a false positive or false
+ * negative.
+ *
+ * *NOT* thread safe.  Calls |Print()|.
+ *
+ * FIXME bug 456272 hack alert: because we can't write call
+ * contexts into strings, all info is written to stderr, but only
+ * some info is written into |aOut|
+ */
+bool
+PrintCycle(const BlockingResourceBase::DDT::ResourceAcquisitionArray* aCycle,
+           nsACString& aOut)
+{
+  NS_ASSERTION(aCycle->Length() > 1, "need > 1 element for cycle!");
+
+  bool maybeImminent = true;
+
+  fputs("=== Cyclical dependency starts at\n", stderr);
+  aOut += "Cyclical dependency starts at\n";
+
+  const BlockingResourceBase::DDT::ResourceAcquisitionArray::elem_type res =
+    aCycle->ElementAt(0);
+  maybeImminent &= res->Print(aOut);
+
+  BlockingResourceBase::DDT::ResourceAcquisitionArray::index_type i;
+  BlockingResourceBase::DDT::ResourceAcquisitionArray::size_type len =
+    aCycle->Length();
+  const BlockingResourceBase::DDT::ResourceAcquisitionArray::elem_type* it =
+    1 + aCycle->Elements();
+  for (i = 1; i < len - 1; ++i, ++it) {
+    fputs("\n--- Next dependency:\n", stderr);
+    aOut += "\nNext dependency:\n";
+
+    maybeImminent &= (*it)->Print(aOut);
+  }
+
+  fputs("\n=== Cycle completed at\n", stderr);
+  aOut += "Cycle completed at\n";
+  (*it)->Print(aOut);
+
+  return maybeImminent;
+}
+
+#ifndef MOZ_CALLSTACK_DISABLED
+struct CodeAddressServiceLock final
+{
+  static void Unlock() { }
+  static void Lock() { }
+  static bool IsLocked() { return true; }
+};
+
+struct CodeAddressServiceStringAlloc final
+{
+  static char* copy(const char* aString) { return ::strdup(aString); }
+  static void free(char* aString) { ::free(aString); }
+};
+
+class CodeAddressServiceStringTable final
+{
+public:
+  CodeAddressServiceStringTable() : mSet(32) {}
+
+  const char* Intern(const char* aString)
+  {
+    nsCharPtrHashKey* e = mSet.PutEntry(aString);
+    return e->GetKey();
+  }
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return mSet.SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+private:
+  typedef nsTHashtable<nsCharPtrHashKey> StringSet;
+  StringSet mSet;
+};
+
+typedef CodeAddressService<CodeAddressServiceStringTable,
+                           CodeAddressServiceStringAlloc,
+                           CodeAddressServiceLock> WalkTheStackCodeAddressService;
+#endif
+
+bool
+BlockingResourceBase::Print(nsACString& aOut) const
+{
+  fprintf(stderr, "--- %s : %s",
+          kResourceTypeName[mType], mName);
+  aOut += BlockingResourceBase::kResourceTypeName[mType];
+  aOut += " : ";
+  aOut += mName;
+
+  bool acquired = IsAcquired();
+
+  if (acquired) {
+    fputs(" (currently acquired)\n", stderr);
+    aOut += " (currently acquired)\n";
+  }
+
+  fputs(" calling context\n", stderr);
+#ifdef MOZ_CALLSTACK_DISABLED
+  fputs("  [stack trace unavailable]\n", stderr);
+#else
+  const AcquisitionState& state = acquired ? mAcquired : mFirstSeen;
+
+  WalkTheStackCodeAddressService addressService;
+
+  for (uint32_t i = 0; i < state.Length(); i++) {
+    const size_t kMaxLength = 1024;
+    char buffer[kMaxLength];
+    addressService.GetLocation(i + 1, state[i], buffer, kMaxLength);
+    const char* fmt = "    %s\n";
+    aOut.AppendLiteral("    ");
+    aOut.Append(buffer);
+    aOut.AppendLiteral("\n");
+    fprintf(stderr, fmt, buffer);
+  }
+
+#endif
+
+  return acquired;
+}
+
+
+BlockingResourceBase::BlockingResourceBase(
+    const char* aName,
+    BlockingResourceBase::BlockingResourceType aType)
+  : mName(aName)
+  , mType(aType)
+#ifdef MOZ_CALLSTACK_DISABLED
+  , mAcquired(false)
+#else
+  , mAcquired()
+#endif
+{
+  MOZ_ASSERT(mName, "Name must be nonnull");
+  // PR_CallOnce guaranatees that InitStatics is called in a
+  // thread-safe way
+  if (PR_SUCCESS != PR_CallOnce(&sCallOnce, InitStatics)) {
+    NS_RUNTIMEABORT("can't initialize blocking resource static members");
+  }
+
+  mChainPrev = 0;
+  sDeadlockDetector->Add(this);
+}
+
+
+BlockingResourceBase::~BlockingResourceBase()
+{
+  // we don't check for really obviously bad things like freeing
+  // Mutexes while they're still locked.  it is assumed that the
+  // base class, or its underlying primitive, will check for such
+  // stupid mistakes.
+  mChainPrev = 0;             // racy only for stupidly buggy client code
+  if (sDeadlockDetector) {
+    sDeadlockDetector->Remove(this);
+  }
+}
+
+
+size_t
+BlockingResourceBase::SizeOfDeadlockDetector(MallocSizeOf aMallocSizeOf)
+{
+  return sDeadlockDetector ?
+      sDeadlockDetector->SizeOfIncludingThis(aMallocSizeOf) : 0;
+}
+
+
+PRStatus
+BlockingResourceBase::InitStatics()
+{
+  PR_NewThreadPrivateIndex(&sResourceAcqnChainFrontTPI, 0);
+  sDeadlockDetector = new DDT();
+  if (!sDeadlockDetector) {
+    NS_RUNTIMEABORT("can't allocate deadlock detector");
+  }
+  return PR_SUCCESS;
+}
+
+
+void
+BlockingResourceBase::Shutdown()
+{
+  delete sDeadlockDetector;
+  sDeadlockDetector = 0;
+}
+
+
+void
+BlockingResourceBase::CheckAcquire()
+{
+  if (mType == eCondVar) {
+    NS_NOTYETIMPLEMENTED(
+      "FIXME bug 456272: annots. to allow CheckAcquire()ing condvars");
+    return;
+  }
+
+  BlockingResourceBase* chainFront = ResourceChainFront();
+  nsAutoPtr<DDT::ResourceAcquisitionArray> cycle(
+    sDeadlockDetector->CheckAcquisition(
+      chainFront ? chainFront : 0, this));
+  if (!cycle) {
+    return;
+  }
+
+#ifndef MOZ_CALLSTACK_DISABLED
+  // Update the current stack before printing.
+  GetStackTrace(mAcquired);
+#endif
+
+  fputs("###!!! ERROR: Potential deadlock detected:\n", stderr);
+  nsAutoCString out("Potential deadlock detected:\n");
+  bool maybeImminent = PrintCycle(cycle, out);
+
+  if (maybeImminent) {
+    fputs("\n###!!! Deadlock may happen NOW!\n\n", stderr);
+    out.AppendLiteral("\n###!!! Deadlock may happen NOW!\n\n");
+  } else {
+    fputs("\nDeadlock may happen for some other execution\n\n",
+          stderr);
+    out.AppendLiteral("\nDeadlock may happen for some other execution\n\n");
+  }
+
+  // XXX can customize behavior on whether we /think/ deadlock is
+  // XXX about to happen.  for example:
+  // XXX   if (maybeImminent)
+  //           NS_RUNTIMEABORT(out.get());
+  NS_ERROR(out.get());
+}
+
+
+void
+BlockingResourceBase::Acquire()
+{
+  if (mType == eCondVar) {
+    NS_NOTYETIMPLEMENTED(
+      "FIXME bug 456272: annots. to allow Acquire()ing condvars");
+    return;
+  }
+  NS_ASSERTION(!IsAcquired(),
+               "reacquiring already acquired resource");
+
+  ResourceChainAppend(ResourceChainFront());
+
+#ifdef MOZ_CALLSTACK_DISABLED
+  mAcquired = true;
+#else
+  // Take a stack snapshot.
+  GetStackTrace(mAcquired);
+  if (mFirstSeen.IsEmpty()) {
+    mFirstSeen = mAcquired;
+  }
+#endif
+}
+
+
+void
+BlockingResourceBase::Release()
+{
+  if (mType == eCondVar) {
+    NS_NOTYETIMPLEMENTED(
+      "FIXME bug 456272: annots. to allow Release()ing condvars");
+    return;
+  }
+
+  BlockingResourceBase* chainFront = ResourceChainFront();
+  NS_ASSERTION(chainFront && IsAcquired(),
+               "Release()ing something that hasn't been Acquire()ed");
+
+  if (chainFront == this) {
+    ResourceChainRemove();
+  } else {
+    // not an error, but makes code hard to reason about.
+    NS_WARNING("Resource acquired is being released in non-LIFO order; why?\n");
+    nsCString tmp;
+    Print(tmp);
+
+    // remove this resource from wherever it lives in the chain
+    // we walk backwards in order of acquisition:
+    //  (1)  ...node<-prev<-curr...
+    //              /     /
+    //  (2)  ...prev<-curr...
+    BlockingResourceBase* curr = chainFront;
+    BlockingResourceBase* prev = nullptr;
+    while (curr && (prev = curr->mChainPrev) && (prev != this)) {
+      curr = prev;
+    }
+    if (prev == this) {
+      curr->mChainPrev = prev->mChainPrev;
+    }
+  }
+
+  ClearAcquisitionState();
+}
+
+
+//
+// Debug implementation of (OffTheBooks)Mutex
+void
+OffTheBooksMutex::Lock()
+{
+  CheckAcquire();
+  PR_Lock(mLock);
+  Acquire();       // protected by mLock
+}
+
+void
+OffTheBooksMutex::Unlock()
+{
+  Release();                  // protected by mLock
+  PRStatus status = PR_Unlock(mLock);
+  NS_ASSERTION(PR_SUCCESS == status, "bad Mutex::Unlock()");
+}
+
+
+//
+// Debug implementation of ReentrantMonitor
+void
+ReentrantMonitor::Enter()
+{
+  BlockingResourceBase* chainFront = ResourceChainFront();
+
+  // the code below implements monitor reentrancy semantics
+
+  if (this == chainFront) {
+    // immediately re-entered the monitor: acceptable
+    PR_EnterMonitor(mReentrantMonitor);
+    ++mEntryCount;
+    return;
+  }
+
+  // this is sort of a hack around not recording the thread that
+  // owns this monitor
+  if (chainFront) {
+    for (BlockingResourceBase* br = ResourceChainPrev(chainFront);
+         br;
+         br = ResourceChainPrev(br)) {
+      if (br == this) {
+        NS_WARNING(
+          "Re-entering ReentrantMonitor after acquiring other resources.");
+
+        // show the caller why this is potentially bad
+        CheckAcquire();
+
+        PR_EnterMonitor(mReentrantMonitor);
+        ++mEntryCount;
+        return;
+      }
+    }
+  }
+
+  CheckAcquire();
+  PR_EnterMonitor(mReentrantMonitor);
+  NS_ASSERTION(mEntryCount == 0, "ReentrantMonitor isn't free!");
+  Acquire();       // protected by mReentrantMonitor
+  mEntryCount = 1;
+}
+
+void
+ReentrantMonitor::Exit()
+{
+  if (--mEntryCount == 0) {
+    Release();              // protected by mReentrantMonitor
+  }
+  PRStatus status = PR_ExitMonitor(mReentrantMonitor);
+  NS_ASSERTION(PR_SUCCESS == status, "bad ReentrantMonitor::Exit()");
+}
+
+nsresult
+ReentrantMonitor::Wait(PRIntervalTime aInterval)
+{
+  AssertCurrentThreadIn();
+
+  // save monitor state and reset it to empty
+  int32_t savedEntryCount = mEntryCount;
+  AcquisitionState savedAcquisitionState = GetAcquisitionState();
+  BlockingResourceBase* savedChainPrev = mChainPrev;
+  mEntryCount = 0;
+  ClearAcquisitionState();
+  mChainPrev = 0;
+
+  nsresult rv;
+#if defined(MOZILLA_INTERNAL_API)
+  {
+    GeckoProfilerSleepRAII profiler_sleep;
+#endif //MOZILLA_INTERNAL_API
+
+    // give up the monitor until we're back from Wait()
+    rv = PR_Wait(mReentrantMonitor, aInterval) == PR_SUCCESS ? NS_OK :
+                                                               NS_ERROR_FAILURE;
+
+#if defined(MOZILLA_INTERNAL_API)
+  }
+#endif //MOZILLA_INTERNAL_API
+
+  // restore saved state
+  mEntryCount = savedEntryCount;
+  SetAcquisitionState(savedAcquisitionState);
+  mChainPrev = savedChainPrev;
+
+  return rv;
+}
+
+
+//
+// Debug implementation of CondVar
+nsresult
+CondVar::Wait(PRIntervalTime aInterval)
+{
+  AssertCurrentThreadOwnsMutex();
+
+  // save mutex state and reset to empty
+  AcquisitionState savedAcquisitionState = mLock->GetAcquisitionState();
+  BlockingResourceBase* savedChainPrev = mLock->mChainPrev;
+  mLock->ClearAcquisitionState();
+  mLock->mChainPrev = 0;
+
+  // give up mutex until we're back from Wait()
+  nsresult rv =
+    PR_WaitCondVar(mCvar, aInterval) == PR_SUCCESS ? NS_OK : NS_ERROR_FAILURE;
+
+  // restore saved state
+  mLock->SetAcquisitionState(savedAcquisitionState);
+  mLock->mChainPrev = savedChainPrev;
+
+  return rv;
+}
+
+#endif // ifdef DEBUG
+
+
+} // namespace mozilla
diff --git a/xpcom/glue/BlockingResourceBase.h b/xpcom/glue/BlockingResourceBase.h
new file mode 100644
index 0000000000..d70fbcbbf3
--- /dev/null
+++ b/xpcom/glue/BlockingResourceBase.h
@@ -0,0 +1,344 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#ifndef mozilla_BlockingResourceBase_h
+#define mozilla_BlockingResourceBase_h
+
+#include "mozilla/Logging.h"
+
+#include "nscore.h"
+#include "nsDebug.h"
+#include "nsError.h"
+#include "nsISupportsImpl.h"
+
+#ifdef DEBUG
+
+// NB: Comment this out to enable callstack tracking.
+#define MOZ_CALLSTACK_DISABLED
+
+#include "prinit.h"
+
+#include "nsStringGlue.h"
+
+#ifndef MOZ_CALLSTACK_DISABLED
+#include "nsTArray.h"
+#endif
+
+#include "nsXPCOM.h"
+#endif
+
+//
+// This header is not meant to be included by client code.
+//
+
+namespace mozilla {
+
+#ifdef DEBUG
+template <class T> class DeadlockDetector;
+#endif
+
+/**
+ * BlockingResourceBase
+ * Base class of resources that might block clients trying to acquire them.
+ * Does debugging and deadlock detection in DEBUG builds.
+ **/
+class BlockingResourceBase
+{
+public:
+  // Needs to be kept in sync with kResourceTypeNames.
+  enum BlockingResourceType { eMutex, eReentrantMonitor, eCondVar };
+
+  /**
+   * kResourceTypeName
+   * Human-readable version of BlockingResourceType enum.
+   */
+  static const char* const kResourceTypeName[];
+
+
+#ifdef DEBUG
+
+  static size_t
+  SizeOfDeadlockDetector(MallocSizeOf aMallocSizeOf);
+
+  /**
+   * Print
+   * Write a description of this blocking resource to |aOut|.  If
+   * the resource appears to be currently acquired, the current
+   * acquisition context is printed and true is returned.
+   * Otherwise, we print the context from |aFirstSeen|, the
+   * first acquisition from which the code calling |Print()|
+   * became interested in us, and return false.
+   *
+   * *NOT* thread safe.  Reads |mAcquisitionContext| without
+   * synchronization, but this will not cause correctness
+   * problems.
+   *
+   * FIXME bug 456272: hack alert: because we can't write call
+   * contexts into strings, all info is written to stderr, but
+   * only some info is written into |aOut|
+   */
+  bool Print(nsACString& aOut) const;
+
+  size_t
+  SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    // NB: |mName| is not reported as it's expected to be a static string.
+    //     If we switch to a nsString it should be added to the tally.
+    //     |mChainPrev| is not reported because its memory is not owned.
+    size_t n = aMallocSizeOf(this);
+    return n;
+  }
+
+  // ``DDT'' = ``Deadlock Detector Type''
+  typedef DeadlockDetector<BlockingResourceBase> DDT;
+
+protected:
+#ifdef MOZ_CALLSTACK_DISABLED
+  typedef bool AcquisitionState;
+#else
+  typedef AutoTArray<void*, 24> AcquisitionState;
+#endif
+
+  /**
+   * BlockingResourceBase
+   * Initialize this blocking resource.  Also hooks the resource into
+   * instrumentation code.
+   *
+   * Thread safe.
+   *
+   * @param aName A meaningful, unique name that can be used in
+   *              error messages, et al.
+   * @param aType The specific type of |this|, if any.
+   **/
+  BlockingResourceBase(const char* aName, BlockingResourceType aType);
+
+  ~BlockingResourceBase();
+
+  /**
+   * CheckAcquire
+   *
+   * Thread safe.
+   **/
+  void CheckAcquire();
+
+  /**
+   * Acquire
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   **/
+  void Acquire(); //NS_NEEDS_RESOURCE(this)
+
+  /**
+   * Release
+   * Remove this resource from the current thread's acquisition chain.
+   * The resource does not have to be at the front of the chain, although
+   * it is confusing to release resources in a different order than they
+   * are acquired.  This generates a warning.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   **/
+  void Release();             //NS_NEEDS_RESOURCE(this)
+
+  /**
+   * ResourceChainFront
+   *
+   * Thread safe.
+   *
+   * @return the front of the resource acquisition chain, i.e., the last
+   *         resource acquired.
+   */
+  static BlockingResourceBase* ResourceChainFront()
+  {
+    return
+      (BlockingResourceBase*)PR_GetThreadPrivate(sResourceAcqnChainFrontTPI);
+  }
+
+  /**
+   * ResourceChainPrev
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  static BlockingResourceBase* ResourceChainPrev(
+      const BlockingResourceBase* aResource)
+  {
+    return aResource->mChainPrev;
+  } //NS_NEEDS_RESOURCE(this)
+
+  /**
+   * ResourceChainAppend
+   * Set |this| to the front of the resource acquisition chain, and link
+   * |this| to |aPrev|.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  void ResourceChainAppend(BlockingResourceBase* aPrev)
+  {
+    mChainPrev = aPrev;
+    PR_SetThreadPrivate(sResourceAcqnChainFrontTPI, this);
+  } //NS_NEEDS_RESOURCE(this)
+
+  /**
+   * ResourceChainRemove
+   * Remove |this| from the front of the resource acquisition chain.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  void ResourceChainRemove()
+  {
+    NS_ASSERTION(this == ResourceChainFront(), "not at chain front");
+    PR_SetThreadPrivate(sResourceAcqnChainFrontTPI, mChainPrev);
+  } //NS_NEEDS_RESOURCE(this)
+
+  /**
+   * GetAcquisitionState
+   * Return whether or not this resource was acquired.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  AcquisitionState GetAcquisitionState()
+  {
+    return mAcquired;
+  }
+
+  /**
+   * SetAcquisitionState
+   * Set whether or not this resource was acquired.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  void SetAcquisitionState(const AcquisitionState& aAcquisitionState)
+  {
+    mAcquired = aAcquisitionState;
+  }
+
+  /**
+   * ClearAcquisitionState
+   * Indicate this resource is not acquired.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  void ClearAcquisitionState()
+  {
+#ifdef MOZ_CALLSTACK_DISABLED
+    mAcquired = false;
+#else
+    mAcquired.Clear();
+#endif
+  }
+
+  /**
+   * IsAcquired
+   * Indicates if this resource is acquired.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  bool IsAcquired() const
+  {
+#ifdef MOZ_CALLSTACK_DISABLED
+    return mAcquired;
+#else
+    return !mAcquired.IsEmpty();
+#endif
+  }
+
+  /**
+   * mChainPrev
+   * A series of resource acquisitions creates a chain of orders.  This
+   * chain is implemented as a linked list; |mChainPrev| points to the
+   * resource most recently Acquire()'d before this one.
+   **/
+  BlockingResourceBase* mChainPrev;
+
+private:
+  /**
+   * mName
+   * A descriptive name for this resource.  Used in error
+   * messages etc.
+   */
+  const char* mName;
+
+  /**
+   * mType
+   * The more specific type of this resource.  Used to implement
+   * special semantics (e.g., reentrancy of monitors).
+   **/
+  BlockingResourceType mType;
+
+  /**
+   * mAcquired
+   * Indicates if this resource is currently acquired.
+   */
+  AcquisitionState mAcquired;
+
+#ifndef MOZ_CALLSTACK_DISABLED
+  /**
+   * mFirstSeen
+   * Inidicates where this resource was first acquired.
+   */
+  AcquisitionState mFirstSeen;
+#endif
+
+  /**
+   * sCallOnce
+   * Ensures static members are initialized only once, and in a
+   * thread-safe way.
+   */
+  static PRCallOnceType sCallOnce;
+
+  /**
+   * sResourceAcqnChainFrontTPI
+   * Thread-private index to the front of each thread's resource
+   * acquisition chain.
+   */
+  static unsigned sResourceAcqnChainFrontTPI;
+
+  /**
+   * sDeadlockDetector
+   * Does as named.
+   */
+  static DDT* sDeadlockDetector;
+
+  /**
+   * InitStatics
+   * Inititialize static members of BlockingResourceBase that can't
+   * be statically initialized.
+   *
+   * *NOT* thread safe.
+   */
+  static PRStatus InitStatics();
+
+  /**
+   * Shutdown
+   * Free static members.
+   *
+   * *NOT* thread safe.
+   */
+  static void Shutdown();
+
+  static void StackWalkCallback(uint32_t aFrameNumber, void* aPc,
+                                void* aSp, void* aClosure);
+  static void GetStackTrace(AcquisitionState& aState);
+
+#  ifdef MOZILLA_INTERNAL_API
+  // so it can call BlockingResourceBase::Shutdown()
+  friend void LogTerm();
+#  endif  // ifdef MOZILLA_INTERNAL_API
+
+#else  // non-DEBUG implementation
+
+  BlockingResourceBase(const char* aName, BlockingResourceType aType) {}
+
+  ~BlockingResourceBase() {}
+
+#endif
+};
+
+
+} // namespace mozilla
+
+
+#endif // mozilla_BlockingResourceBase_h
diff --git a/xpcom/glue/CondVar.h b/xpcom/glue/CondVar.h
new file mode 100644
index 0000000000..5d05464eca
--- /dev/null
+++ b/xpcom/glue/CondVar.h
@@ -0,0 +1,144 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_CondVar_h
+#define mozilla_CondVar_h
+
+#include "prcvar.h"
+
+#include "mozilla/BlockingResourceBase.h"
+#include "mozilla/Mutex.h"
+
+#ifdef MOZILLA_INTERNAL_API
+#include "GeckoProfiler.h"
+#endif //MOZILLA_INTERNAL_API
+
+namespace mozilla {
+
+
+/**
+ * CondVar
+ * Vanilla condition variable.  Please don't use this unless you have a
+ * compelling reason --- Monitor provides a simpler API.
+ */
+class CondVar : BlockingResourceBase
+{
+public:
+  /**
+   * CondVar
+   *
+   * The CALLER owns |aLock|.
+   *
+   * @param aLock A Mutex to associate with this condition variable.
+   * @param aName A name which can reference this monitor
+   * @returns If failure, nullptr.
+   *          If success, a valid Monitor* which must be destroyed
+   *          by Monitor::DestroyMonitor()
+   **/
+  CondVar(Mutex& aLock, const char* aName)
+    : BlockingResourceBase(aName, eCondVar)
+    , mLock(&aLock)
+  {
+    MOZ_COUNT_CTOR(CondVar);
+    // |aLock| must necessarily already be known to the deadlock detector
+    mCvar = PR_NewCondVar(mLock->mLock);
+    if (!mCvar) {
+      NS_RUNTIMEABORT("Can't allocate mozilla::CondVar");
+    }
+  }
+
+  /**
+   * ~CondVar
+   * Clean up after this CondVar, but NOT its associated Mutex.
+   **/
+  ~CondVar()
+  {
+    NS_ASSERTION(mCvar && mLock,
+                 "improperly constructed CondVar or double free");
+    PR_DestroyCondVar(mCvar);
+    mCvar = 0;
+    mLock = 0;
+    MOZ_COUNT_DTOR(CondVar);
+  }
+
+#ifndef DEBUG
+  /**
+   * Wait
+   * @see prcvar.h
+   **/
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT)
+  {
+
+#ifdef MOZILLA_INTERNAL_API
+    GeckoProfilerSleepRAII profiler_sleep;
+#endif //MOZILLA_INTERNAL_API
+    // NSPR checks for lock ownership
+    return PR_WaitCondVar(mCvar, aInterval) == PR_SUCCESS ? NS_OK :
+                                                            NS_ERROR_FAILURE;
+  }
+#else
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT);
+#endif // ifndef DEBUG
+
+  /**
+   * Notify
+   * @see prcvar.h
+   **/
+  nsresult Notify()
+  {
+    // NSPR checks for lock ownership
+    return PR_NotifyCondVar(mCvar) == PR_SUCCESS ? NS_OK : NS_ERROR_FAILURE;
+  }
+
+  /**
+   * NotifyAll
+   * @see prcvar.h
+   **/
+  nsresult NotifyAll()
+  {
+    // NSPR checks for lock ownership
+    return PR_NotifyAllCondVar(mCvar) == PR_SUCCESS ? NS_OK : NS_ERROR_FAILURE;
+  }
+
+#ifdef DEBUG
+  /**
+   * AssertCurrentThreadOwnsMutex
+   * @see Mutex::AssertCurrentThreadOwns
+   **/
+  void AssertCurrentThreadOwnsMutex()
+  {
+    mLock->AssertCurrentThreadOwns();
+  }
+
+  /**
+   * AssertNotCurrentThreadOwnsMutex
+   * @see Mutex::AssertNotCurrentThreadOwns
+   **/
+  void AssertNotCurrentThreadOwnsMutex()
+  {
+    mLock->AssertNotCurrentThreadOwns();
+  }
+
+#else
+  void AssertCurrentThreadOwnsMutex() {}
+  void AssertNotCurrentThreadOwnsMutex() {}
+
+#endif  // ifdef DEBUG
+
+private:
+  CondVar();
+  CondVar(CondVar&);
+  CondVar& operator=(CondVar&);
+
+  Mutex* mLock;
+  PRCondVar* mCvar;
+};
+
+
+} // namespace mozilla
+
+
+#endif  // ifndef mozilla_CondVar_h  
diff --git a/xpcom/glue/DeadlockDetector.h b/xpcom/glue/DeadlockDetector.h
new file mode 100644
index 0000000000..382e4ef4a7
--- /dev/null
+++ b/xpcom/glue/DeadlockDetector.h
@@ -0,0 +1,382 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef mozilla_DeadlockDetector_h
+#define mozilla_DeadlockDetector_h
+
+#include "mozilla/Attributes.h"
+
+#include <stdlib.h>
+
+#include "prlock.h"
+
+#include "nsClassHashtable.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+
+/**
+ * DeadlockDetector
+ *
+ * The following is an approximate description of how the deadlock detector
+ * works.
+ *
+ * The deadlock detector ensures that all blocking resources are
+ * acquired according to a partial order P.  One type of blocking
+ * resource is a lock.  If a lock l1 is acquired (locked) before l2,
+ * then we say that |l1 <_P l2|.  The detector flags an error if two
+ * locks l1 and l2 have an inconsistent ordering in P; that is, if
+ * both |l1 <_P l2| and |l2 <_P l1|.  This is a potential error
+ * because a thread acquiring l1,l2 according to the first order might
+ * race with a thread acquiring them according to the second order.
+ * If this happens under the right conditions, then the acquisitions
+ * will deadlock.
+ *
+ * This deadlock detector doesn't know at compile-time what P is.  So,
+ * it tries to discover the order at run time.  More precisely, it
+ * finds <i>some</i> order P, then tries to find chains of resource
+ * acquisitions that violate P.  An example acquisition sequence, and
+ * the orders they impose, is
+ *   l1.lock()   // current chain: [ l1 ]
+ *               // order: { }
+ *
+ *   l2.lock()   // current chain: [ l1, l2 ]
+ *               // order: { l1 <_P l2 }
+ *
+ *   l3.lock()   // current chain: [ l1, l2, l3 ]
+ *               // order: { l1 <_P l2, l2 <_P l3, l1 <_P l3 }
+ *               // (note: <_P is transitive, so also |l1 <_P l3|)
+ *
+ *   l2.unlock() // current chain: [ l1, l3 ]
+ *               // order: { l1 <_P l2, l2 <_P l3, l1 <_P l3 }
+ *               // (note: it's OK, but weird, that l2 was unlocked out
+ *               //  of order.  we still have l1 <_P l3).
+ *
+ *   l2.lock()   // current chain: [ l1, l3, l2 ]
+ *               // order: { l1 <_P l2, l2 <_P l3, l1 <_P l3,
+ *                                      l3 <_P l2 (!!!) }
+ * BEEP BEEP!  Here the detector will flag a potential error, since
+ * l2 and l3 were used inconsistently (and potentially in ways that
+ * would deadlock).
+ */
+template<typename T>
+class DeadlockDetector
+{
+public:
+  typedef nsTArray<const T*> ResourceAcquisitionArray;
+
+private:
+  struct OrderingEntry;
+  typedef nsTArray<OrderingEntry*> HashEntryArray;
+  typedef typename HashEntryArray::index_type index_type;
+  typedef typename HashEntryArray::size_type size_type;
+  static const index_type NoIndex = HashEntryArray::NoIndex;
+
+  /**
+   * Value type for the ordering table.  Contains the other
+   * resources on which an ordering constraint |key < other|
+   * exists.  The catch is that we also store the calling context at
+   * which the other resource was acquired; this improves the
+   * quality of error messages when potential deadlock is detected.
+   */
+  struct OrderingEntry
+  {
+    explicit OrderingEntry(const T* aResource)
+      : mOrderedLT()        // FIXME bug 456272: set to empirical dep size?
+      , mExternalRefs()
+      , mResource(aResource)
+    {
+    }
+    ~OrderingEntry()
+    {
+    }
+
+    size_t
+    SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+    {
+      size_t n = aMallocSizeOf(this);
+      n += mOrderedLT.ShallowSizeOfExcludingThis(aMallocSizeOf);
+      n += mExternalRefs.ShallowSizeOfExcludingThis(aMallocSizeOf);
+      return n;
+    }
+
+    HashEntryArray mOrderedLT; // this <_o Other
+    HashEntryArray mExternalRefs; // hash entries that reference this
+    const T* mResource;
+  };
+
+  // Throwaway RAII lock to make the following code safer.
+  struct PRAutoLock
+  {
+    explicit PRAutoLock(PRLock* aLock) : mLock(aLock) { PR_Lock(mLock); }
+    ~PRAutoLock() { PR_Unlock(mLock); }
+    PRLock* mLock;
+  };
+
+public:
+  static const uint32_t kDefaultNumBuckets;
+
+  /**
+   * DeadlockDetector
+   * Create a new deadlock detector.
+   *
+   * @param aNumResourcesGuess Guess at approximate number of resources
+   *        that will be checked.
+   */
+  explicit DeadlockDetector(uint32_t aNumResourcesGuess = kDefaultNumBuckets)
+    : mOrdering(aNumResourcesGuess)
+  {
+    mLock = PR_NewLock();
+    if (!mLock) {
+      NS_RUNTIMEABORT("couldn't allocate deadlock detector lock");
+    }
+  }
+
+  /**
+   * ~DeadlockDetector
+   *
+   * *NOT* thread safe.
+   */
+  ~DeadlockDetector()
+  {
+    PR_DestroyLock(mLock);
+  }
+
+  size_t
+  SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    size_t n = aMallocSizeOf(this);
+
+    {
+      PRAutoLock _(mLock);
+      n += mOrdering.ShallowSizeOfExcludingThis(aMallocSizeOf);
+      for (auto iter = mOrdering.ConstIter(); !iter.Done(); iter.Next()) {
+        // NB: Key is accounted for in the entry.
+        n += iter.Data()->SizeOfIncludingThis(aMallocSizeOf);
+      }
+    }
+
+    return n;
+  }
+
+  /**
+   * Add
+   * Make the deadlock detector aware of |aResource|.
+   *
+   * WARNING: The deadlock detector owns |aResource|.
+   *
+   * Thread safe.
+   *
+   * @param aResource Resource to make deadlock detector aware of.
+   */
+  void Add(const T* aResource)
+  {
+    PRAutoLock _(mLock);
+    mOrdering.Put(aResource, new OrderingEntry(aResource));
+  }
+
+  void Remove(const T* aResource)
+  {
+    PRAutoLock _(mLock);
+
+    OrderingEntry* entry = mOrdering.Get(aResource);
+
+    // Iterate the external refs and remove the entry from them.
+    HashEntryArray& refs = entry->mExternalRefs;
+    for (index_type i = 0; i < refs.Length(); i++) {
+      refs[i]->mOrderedLT.RemoveElementSorted(entry);
+    }
+
+    // Iterate orders and remove this entry from their refs.
+    HashEntryArray& orders = entry->mOrderedLT;
+    for (index_type i = 0; i < orders.Length(); i++) {
+      orders[i]->mExternalRefs.RemoveElementSorted(entry);
+    }
+
+    // Now the entry can be safely removed.
+    mOrdering.Remove(aResource);
+  }
+
+  /**
+   * CheckAcquisition This method is called after acquiring |aLast|,
+   * but before trying to acquire |aProposed|.
+   * It determines whether actually trying to acquire |aProposed|
+   * will create problems.  It is OK if |aLast| is nullptr; this is
+   * interpreted as |aProposed| being the thread's first acquisition
+   * of its current chain.
+   *
+   * Iff acquiring |aProposed| may lead to deadlock for some thread
+   * interleaving (including the current one!), the cyclical
+   * dependency from which this was deduced is returned.  Otherwise,
+   * 0 is returned.
+   *
+   * If a potential deadlock is detected and a resource cycle is
+   * returned, it is the *caller's* responsibility to free it.
+   *
+   * Thread safe.
+   *
+   * @param aLast Last resource acquired by calling thread (or 0).
+   * @param aProposed Resource calling thread proposes to acquire.
+   */
+  ResourceAcquisitionArray* CheckAcquisition(const T* aLast,
+                                             const T* aProposed)
+  {
+    if (!aLast) {
+      // don't check if |0 < aProposed|; just vamoose
+      return 0;
+    }
+
+    NS_ASSERTION(aProposed, "null resource");
+    PRAutoLock _(mLock);
+
+    OrderingEntry* proposed = mOrdering.Get(aProposed);
+    NS_ASSERTION(proposed, "missing ordering entry");
+
+    OrderingEntry* current = mOrdering.Get(aLast);
+    NS_ASSERTION(current, "missing ordering entry");
+
+    // this is the crux of the deadlock detector algorithm
+
+    if (current == proposed) {
+      // reflexive deadlock.  fastpath b/c InTransitiveClosure is
+      // not applicable here.
+      ResourceAcquisitionArray* cycle = new ResourceAcquisitionArray();
+      if (!cycle) {
+        NS_RUNTIMEABORT("can't allocate dep. cycle array");
+      }
+      cycle->AppendElement(current->mResource);
+      cycle->AppendElement(aProposed);
+      return cycle;
+    }
+    if (InTransitiveClosure(current, proposed)) {
+      // we've already established |aLast < aProposed|.  all is well.
+      return 0;
+    }
+    if (InTransitiveClosure(proposed, current)) {
+      // the order |aProposed < aLast| has been deduced, perhaps
+      // transitively.  we're attempting to violate that
+      // constraint by acquiring resources in the order
+      // |aLast < aProposed|, and thus we may deadlock under the
+      // right conditions.
+      ResourceAcquisitionArray* cycle = GetDeductionChain(proposed, current);
+      // show how acquiring |aProposed| would complete the cycle
+      cycle->AppendElement(aProposed);
+      return cycle;
+    }
+    // |aLast|, |aProposed| are unordered according to our
+    // poset.  this is fine, but we now need to add this
+    // ordering constraint.
+    current->mOrderedLT.InsertElementSorted(proposed);
+    proposed->mExternalRefs.InsertElementSorted(current);
+    return 0;
+  }
+
+  /**
+   * Return true iff |aTarget| is in the transitive closure of |aStart|
+   * over the ordering relation `<_this'.
+   *
+   * @precondition |aStart != aTarget|
+   */
+  bool InTransitiveClosure(const OrderingEntry* aStart,
+                           const OrderingEntry* aTarget) const
+  {
+    // NB: Using a static comparator rather than default constructing one shows
+    //     a 9% improvement in scalability tests on some systems.
+    static nsDefaultComparator<const OrderingEntry*, const OrderingEntry*> comp;
+    if (aStart->mOrderedLT.BinaryIndexOf(aTarget, comp) != NoIndex) {
+      return true;
+    }
+
+    index_type i = 0;
+    size_type len = aStart->mOrderedLT.Length();
+    for (auto it = aStart->mOrderedLT.Elements(); i < len; ++i, ++it) {
+      if (InTransitiveClosure(*it, aTarget)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Return an array of all resource acquisitions
+   *   aStart <_this r1 <_this r2 <_ ... <_ aTarget
+   * from which |aStart <_this aTarget| was deduced, including
+   * |aStart| and |aTarget|.
+   *
+   * Nb: there may be multiple deductions of |aStart <_this
+   * aTarget|.  This function returns the first ordering found by
+   * depth-first search.
+   *
+   * Nb: |InTransitiveClosure| could be replaced by this function.
+   * However, this one is more expensive because we record the DFS
+   * search stack on the heap whereas the other doesn't.
+   *
+   * @precondition |aStart != aTarget|
+   */
+  ResourceAcquisitionArray* GetDeductionChain(const OrderingEntry* aStart,
+                                              const OrderingEntry* aTarget)
+  {
+    ResourceAcquisitionArray* chain = new ResourceAcquisitionArray();
+    if (!chain) {
+      NS_RUNTIMEABORT("can't allocate dep. cycle array");
+    }
+    chain->AppendElement(aStart->mResource);
+
+    NS_ASSERTION(GetDeductionChain_Helper(aStart, aTarget, chain),
+                 "GetDeductionChain called when there's no deadlock");
+    return chain;
+  }
+
+  // precondition: |aStart != aTarget|
+  // invariant: |aStart| is the last element in |aChain|
+  bool GetDeductionChain_Helper(const OrderingEntry* aStart,
+                                const OrderingEntry* aTarget,
+                                ResourceAcquisitionArray* aChain)
+  {
+    if (aStart->mOrderedLT.BinaryIndexOf(aTarget) != NoIndex) {
+      aChain->AppendElement(aTarget->mResource);
+      return true;
+    }
+
+    index_type i = 0;
+    size_type len = aStart->mOrderedLT.Length();
+    for (auto it = aStart->mOrderedLT.Elements(); i < len; ++i, ++it) {
+      aChain->AppendElement((*it)->mResource);
+      if (GetDeductionChain_Helper(*it, aTarget, aChain)) {
+        return true;
+      }
+      aChain->RemoveElementAt(aChain->Length() - 1);
+    }
+    return false;
+  }
+
+  /**
+   * The partial order on resource acquisitions used by the deadlock
+   * detector.
+   */
+  nsClassHashtable<nsPtrHashKey<const T>, OrderingEntry> mOrdering;
+
+
+  /**
+   * Protects contentious methods.
+   * Nb: can't use mozilla::Mutex since we are used as its deadlock
+   * detector.
+   */
+  PRLock* mLock;
+
+private:
+  DeadlockDetector(const DeadlockDetector& aDD) = delete;
+  DeadlockDetector& operator=(const DeadlockDetector& aDD) = delete;
+};
+
+
+template<typename T>
+// FIXME bug 456272: tune based on average workload
+const uint32_t DeadlockDetector<T>::kDefaultNumBuckets = 32;
+
+
+} // namespace mozilla
+
+#endif // ifndef mozilla_DeadlockDetector_h
diff --git a/xpcom/glue/EnumeratedArrayCycleCollection.h b/xpcom/glue/EnumeratedArrayCycleCollection.h
new file mode 100644
index 0000000000..faabb5a529
--- /dev/null
+++ b/xpcom/glue/EnumeratedArrayCycleCollection.h
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef EnumeratedArrayCycleCollection_h_
+#define EnumeratedArrayCycleCollection_h_
+
+#include "mozilla/EnumeratedArray.h"
+#include "nsCycleCollectionTraversalCallback.h"
+
+template<typename IndexType,
+         IndexType SizeAsEnumValue,
+         typename ValueType>
+inline void
+ImplCycleCollectionUnlink(mozilla::EnumeratedArray<IndexType,
+                                                   SizeAsEnumValue,
+                                                   ValueType>& aField)
+{
+  for (size_t i = 0; i < size_t(SizeAsEnumValue); ++i) {
+    aField[IndexType(i)] = nullptr;
+  }
+}
+
+template<typename IndexType,
+         IndexType SizeAsEnumValue,
+         typename ValueType>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            mozilla::EnumeratedArray<IndexType,
+                                                     SizeAsEnumValue,
+                                                     ValueType>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  aFlags |= CycleCollectionEdgeNameArrayFlag;
+  for (size_t i = 0; i < size_t(SizeAsEnumValue); ++i) {
+    ImplCycleCollectionTraverse(aCallback, aField[IndexType(i)], aName, aFlags);
+  }
+}
+
+#endif // EnumeratedArrayCycleCollection_h_
diff --git a/xpcom/glue/FileUtils.cpp b/xpcom/glue/FileUtils.cpp
new file mode 100644
index 0000000000..699812461f
--- /dev/null
+++ b/xpcom/glue/FileUtils.cpp
@@ -0,0 +1,568 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <errno.h>
+#include <stdio.h>
+
+#include "nscore.h"
+#include "nsStringGlue.h"
+#include "private/pprio.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/FileUtils.h"
+
+#if defined(XP_MACOSX)
+#include <fcntl.h>
+#include <unistd.h>
+#include <mach/machine.h>
+#include <mach-o/fat.h>
+#include <mach-o/loader.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <limits.h>
+#elif defined(XP_UNIX)
+#include <fcntl.h>
+#include <unistd.h>
+#if defined(LINUX)
+#include <elf.h>
+#endif
+#include <sys/types.h>
+#include <sys/stat.h>
+#elif defined(XP_WIN)
+#include <windows.h>
+#endif
+
+// Functions that are not to be used in standalone glue must be implemented
+// within this #if block
+#if !defined(XPCOM_GLUE)
+
+bool
+mozilla::fallocate(PRFileDesc* aFD, int64_t aLength)
+{
+#if defined(HAVE_POSIX_FALLOCATE)
+  return posix_fallocate(PR_FileDesc2NativeHandle(aFD), 0, aLength) == 0;
+#elif defined(XP_WIN)
+  int64_t oldpos = PR_Seek64(aFD, 0, PR_SEEK_CUR);
+  if (oldpos == -1) {
+    return false;
+  }
+
+  if (PR_Seek64(aFD, aLength, PR_SEEK_SET) != aLength) {
+    return false;
+  }
+
+  bool retval = (0 != SetEndOfFile((HANDLE)PR_FileDesc2NativeHandle(aFD)));
+
+  PR_Seek64(aFD, oldpos, PR_SEEK_SET);
+  return retval;
+#elif defined(XP_MACOSX)
+  int fd = PR_FileDesc2NativeHandle(aFD);
+  fstore_t store = {F_ALLOCATECONTIG, F_PEOFPOSMODE, 0, aLength};
+  // Try to get a continous chunk of disk space
+  int ret = fcntl(fd, F_PREALLOCATE, &store);
+  if (ret == -1) {
+    // OK, perhaps we are too fragmented, allocate non-continuous
+    store.fst_flags = F_ALLOCATEALL;
+    ret = fcntl(fd, F_PREALLOCATE, &store);
+    if (ret == -1) {
+      return false;
+    }
+  }
+  return ftruncate(fd, aLength) == 0;
+#elif defined(XP_UNIX)
+  // The following is copied from fcntlSizeHint in sqlite
+  /* If the OS does not have posix_fallocate(), fake it. First use
+  ** ftruncate() to set the file size, then write a single byte to
+  ** the last byte in each block within the extended region. This
+  ** is the same technique used by glibc to implement posix_fallocate()
+  ** on systems that do not have a real fallocate() system call.
+  */
+  int64_t oldpos = PR_Seek64(aFD, 0, PR_SEEK_CUR);
+  if (oldpos == -1) {
+    return false;
+  }
+
+  struct stat buf;
+  int fd = PR_FileDesc2NativeHandle(aFD);
+  if (fstat(fd, &buf)) {
+    return false;
+  }
+
+  if (buf.st_size >= aLength) {
+    return false;
+  }
+
+  const int nBlk = buf.st_blksize;
+
+  if (!nBlk) {
+    return false;
+  }
+
+  if (ftruncate(fd, aLength)) {
+    return false;
+  }
+
+  int nWrite; // Return value from write()
+  int64_t iWrite = ((buf.st_size + 2 * nBlk - 1) / nBlk) * nBlk - 1; // Next offset to write to
+  while (iWrite < aLength) {
+    nWrite = 0;
+    if (PR_Seek64(aFD, iWrite, PR_SEEK_SET) == iWrite) {
+      nWrite = PR_Write(aFD, "", 1);
+    }
+    if (nWrite != 1) {
+      break;
+    }
+    iWrite += nBlk;
+  }
+
+  PR_Seek64(aFD, oldpos, PR_SEEK_SET);
+  return nWrite == 1;
+#endif
+  return false;
+}
+
+#ifdef ReadSysFile_PRESENT
+
+bool
+mozilla::ReadSysFile(
+  const char* aFilename,
+  char* aBuf,
+  size_t aBufSize)
+{
+  int fd = MOZ_TEMP_FAILURE_RETRY(open(aFilename, O_RDONLY));
+  if (fd < 0) {
+    return false;
+  }
+  ScopedClose autoClose(fd);
+  if (aBufSize == 0) {
+    return true;
+  }
+  ssize_t bytesRead;
+  size_t offset = 0;
+  do {
+    bytesRead = MOZ_TEMP_FAILURE_RETRY(read(fd, aBuf + offset,
+                                            aBufSize - offset));
+    if (bytesRead == -1) {
+      return false;
+    }
+    offset += bytesRead;
+  } while (bytesRead > 0 && offset < aBufSize);
+  MOZ_ASSERT(offset <= aBufSize);
+  if (offset > 0 && aBuf[offset - 1] == '\n') {
+    offset--;
+  }
+  if (offset == aBufSize) {
+    MOZ_ASSERT(offset > 0);
+    offset--;
+  }
+  aBuf[offset] = '\0';
+  return true;
+}
+
+bool
+mozilla::ReadSysFile(
+  const char* aFilename,
+  int* aVal)
+{
+  char valBuf[32];
+  if (!ReadSysFile(aFilename, valBuf, sizeof(valBuf))) {
+    return false;
+  }
+  return sscanf(valBuf, "%d", aVal) == 1;
+}
+
+bool
+mozilla::ReadSysFile(
+  const char* aFilename,
+  bool* aVal)
+{
+  int v;
+  if (!ReadSysFile(aFilename, &v)) {
+    return false;
+  }
+  *aVal = (v != 0);
+  return true;
+}
+
+#endif /* ReadSysFile_PRESENT */
+
+#ifdef WriteSysFile_PRESENT
+
+bool
+mozilla::WriteSysFile(
+  const char* aFilename,
+  const char* aBuf)
+{
+  size_t aBufSize = strlen(aBuf);
+  int fd = MOZ_TEMP_FAILURE_RETRY(open(aFilename, O_WRONLY));
+  if (fd < 0) {
+    return false;
+  }
+  ScopedClose autoClose(fd);
+  ssize_t bytesWritten;
+  size_t offset = 0;
+  do {
+    bytesWritten = MOZ_TEMP_FAILURE_RETRY(write(fd, aBuf + offset,
+                                                aBufSize - offset));
+    if (bytesWritten == -1) {
+      return false;
+    }
+    offset += bytesWritten;
+  } while (bytesWritten > 0 && offset < aBufSize);
+  MOZ_ASSERT(offset == aBufSize);
+  return true;
+}
+
+#endif /* WriteSysFile_PRESENT */
+
+void
+mozilla::ReadAheadLib(nsIFile* aFile)
+{
+#if defined(XP_WIN)
+  nsAutoString path;
+  if (!aFile || NS_FAILED(aFile->GetPath(path))) {
+    return;
+  }
+  ReadAheadLib(path.get());
+#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX)
+  nsAutoCString nativePath;
+  if (!aFile || NS_FAILED(aFile->GetNativePath(nativePath))) {
+    return;
+  }
+  ReadAheadLib(nativePath.get());
+#endif
+}
+
+void
+mozilla::ReadAheadFile(nsIFile* aFile, const size_t aOffset,
+                       const size_t aCount, mozilla::filedesc_t* aOutFd)
+{
+#if defined(XP_WIN)
+  nsAutoString path;
+  if (!aFile || NS_FAILED(aFile->GetPath(path))) {
+    return;
+  }
+  ReadAheadFile(path.get(), aOffset, aCount, aOutFd);
+#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX)
+  nsAutoCString nativePath;
+  if (!aFile || NS_FAILED(aFile->GetNativePath(nativePath))) {
+    return;
+  }
+  ReadAheadFile(nativePath.get(), aOffset, aCount, aOutFd);
+#endif
+}
+
+#endif // !defined(XPCOM_GLUE)
+
+#if defined(LINUX) && !defined(ANDROID)
+
+static const unsigned int bufsize = 4096;
+
+#ifdef __LP64__
+typedef Elf64_Ehdr Elf_Ehdr;
+typedef Elf64_Phdr Elf_Phdr;
+static const unsigned char ELFCLASS = ELFCLASS64;
+typedef Elf64_Off Elf_Off;
+#else
+typedef Elf32_Ehdr Elf_Ehdr;
+typedef Elf32_Phdr Elf_Phdr;
+static const unsigned char ELFCLASS = ELFCLASS32;
+typedef Elf32_Off Elf_Off;
+#endif
+
+#elif defined(XP_MACOSX)
+
+#if defined(__i386__)
+static const uint32_t CPU_TYPE = CPU_TYPE_X86;
+#elif defined(__x86_64__)
+static const uint32_t CPU_TYPE = CPU_TYPE_X86_64;
+#elif defined(__ppc__)
+static const uint32_t CPU_TYPE = CPU_TYPE_POWERPC;
+#elif defined(__ppc64__)
+static const uint32_t CPU_TYPE = CPU_TYPE_POWERPC64;
+#else
+#error Unsupported CPU type
+#endif
+
+#ifdef __LP64__
+#undef LC_SEGMENT
+#define LC_SEGMENT LC_SEGMENT_64
+#undef MH_MAGIC
+#define MH_MAGIC MH_MAGIC_64
+#define cpu_mach_header mach_header_64
+#define segment_command segment_command_64
+#else
+#define cpu_mach_header mach_header
+#endif
+
+class ScopedMMap
+{
+public:
+  explicit ScopedMMap(const char* aFilePath)
+    : buf(nullptr)
+  {
+    fd = open(aFilePath, O_RDONLY);
+    if (fd < 0) {
+      return;
+    }
+    struct stat st;
+    if (fstat(fd, &st) < 0) {
+      return;
+    }
+    size = st.st_size;
+    buf = (char*)mmap(nullptr, size, PROT_READ, MAP_PRIVATE, fd, 0);
+  }
+  ~ScopedMMap()
+  {
+    if (buf) {
+      munmap(buf, size);
+    }
+    if (fd >= 0) {
+      close(fd);
+    }
+  }
+  operator char*() { return buf; }
+  int getFd() { return fd; }
+private:
+  int fd;
+  char* buf;
+  size_t size;
+};
+#endif
+
+void
+mozilla::ReadAhead(mozilla::filedesc_t aFd, const size_t aOffset,
+                   const size_t aCount)
+{
+#if defined(XP_WIN)
+
+  LARGE_INTEGER fpOriginal;
+  LARGE_INTEGER fpOffset;
+#if defined(HAVE_LONG_LONG)
+  fpOffset.QuadPart = 0;
+#else
+  fpOffset.u.LowPart = 0;
+  fpOffset.u.HighPart = 0;
+#endif
+
+  // Get the current file pointer so that we can restore it. This isn't
+  // really necessary other than to provide the same semantics regarding the
+  // file pointer that other platforms do
+  if (!SetFilePointerEx(aFd, fpOffset, &fpOriginal, FILE_CURRENT)) {
+    return;
+  }
+
+  if (aOffset) {
+#if defined(HAVE_LONG_LONG)
+    fpOffset.QuadPart = static_cast<LONGLONG>(aOffset);
+#else
+    fpOffset.u.LowPart = aOffset;
+    fpOffset.u.HighPart = 0;
+#endif
+
+    if (!SetFilePointerEx(aFd, fpOffset, nullptr, FILE_BEGIN)) {
+      return;
+    }
+  }
+
+  char buf[64 * 1024];
+  size_t totalBytesRead = 0;
+  DWORD dwBytesRead;
+  // Do dummy reads to trigger kernel-side readhead via FILE_FLAG_SEQUENTIAL_SCAN.
+  // Abort when underfilling because during testing the buffers are read fully
+  // A buffer that's not keeping up would imply that readahead isn't working right
+  while (totalBytesRead < aCount &&
+         ReadFile(aFd, buf, sizeof(buf), &dwBytesRead, nullptr) &&
+         dwBytesRead == sizeof(buf)) {
+    totalBytesRead += dwBytesRead;
+  }
+
+  // Restore the file pointer
+  SetFilePointerEx(aFd, fpOriginal, nullptr, FILE_BEGIN);
+
+#elif defined(LINUX) && !defined(ANDROID)
+
+  readahead(aFd, aOffset, aCount);
+
+#elif defined(XP_MACOSX)
+
+  struct radvisory ra;
+  ra.ra_offset = aOffset;
+  ra.ra_count = aCount;
+  // The F_RDADVISE fcntl is equivalent to Linux' readahead() system call.
+  fcntl(aFd, F_RDADVISE, &ra);
+
+#endif
+}
+
+void
+mozilla::ReadAheadLib(mozilla::pathstr_t aFilePath)
+{
+  if (!aFilePath) {
+    return;
+  }
+#if defined(XP_WIN)
+  ReadAheadFile(aFilePath);
+#elif defined(LINUX) && !defined(ANDROID)
+  int fd = open(aFilePath, O_RDONLY);
+  if (fd < 0) {
+    return;
+  }
+
+  union
+  {
+    char buf[bufsize];
+    Elf_Ehdr ehdr;
+  } elf;
+  // Read ELF header (ehdr) and program header table (phdr).
+  // We check that the ELF magic is found, that the ELF class matches
+  // our own, and that the program header table as defined in the ELF
+  // headers fits in the buffer we read.
+  if ((read(fd, elf.buf, bufsize) <= 0) ||
+      (memcmp(elf.buf, ELFMAG, 4)) ||
+      (elf.ehdr.e_ident[EI_CLASS] != ELFCLASS) ||
+      // Upcast e_phentsize so the multiplication is done in the same precision
+      // as the subsequent addition, to satisfy static analyzers and avoid
+      // issues with abnormally large program header tables.
+      (elf.ehdr.e_phoff + (static_cast<Elf_Off>(elf.ehdr.e_phentsize) *
+                           elf.ehdr.e_phnum) >= bufsize)) {
+    close(fd);
+    return;
+  }
+  // The program header table contains segment definitions. One such
+  // segment type is PT_LOAD, which describes how the dynamic loader
+  // is going to map the file in memory. We use that information to
+  // find the biggest offset from the library that will be mapped in
+  // memory.
+  Elf_Phdr* phdr = (Elf_Phdr*)&elf.buf[elf.ehdr.e_phoff];
+  Elf_Off end = 0;
+  for (int phnum = elf.ehdr.e_phnum; phnum; phdr++, phnum--) {
+    if ((phdr->p_type == PT_LOAD) &&
+        (end < phdr->p_offset + phdr->p_filesz)) {
+      end = phdr->p_offset + phdr->p_filesz;
+    }
+  }
+  // Let the kernel read ahead what the dynamic loader is going to
+  // map in memory soon after.
+  if (end > 0) {
+    ReadAhead(fd, 0, end);
+  }
+  close(fd);
+#elif defined(XP_MACOSX)
+  ScopedMMap buf(aFilePath);
+  char* base = buf;
+  if (!base) {
+    return;
+  }
+
+  // An OSX binary might either be a fat (universal) binary or a
+  // Mach-O binary. A fat binary actually embeds several Mach-O
+  // binaries. If we have a fat binary, find the offset where the
+  // Mach-O binary for our CPU type can be found.
+  struct fat_header* fh = (struct fat_header*)base;
+
+  if (OSSwapBigToHostInt32(fh->magic) == FAT_MAGIC) {
+    uint32_t nfat_arch = OSSwapBigToHostInt32(fh->nfat_arch);
+    struct fat_arch* arch = (struct fat_arch*)&buf[sizeof(struct fat_header)];
+    for (; nfat_arch; arch++, nfat_arch--) {
+      if (OSSwapBigToHostInt32(arch->cputype) == CPU_TYPE) {
+        base += OSSwapBigToHostInt32(arch->offset);
+        break;
+      }
+    }
+    if (base == buf) {
+      return;
+    }
+  }
+
+  // Check Mach-O magic in the Mach header
+  struct cpu_mach_header* mh = (struct cpu_mach_header*)base;
+  if (mh->magic != MH_MAGIC) {
+    return;
+  }
+
+  // The Mach header is followed by a sequence of load commands.
+  // Each command has a header containing the command type and the
+  // command size. LD_SEGMENT commands describes how the dynamic
+  // loader is going to map the file in memory. We use that
+  // information to find the biggest offset from the library that
+  // will be mapped in memory.
+  char* cmd = &base[sizeof(struct cpu_mach_header)];
+  uint32_t end = 0;
+  for (uint32_t ncmds = mh->ncmds; ncmds; ncmds--) {
+    struct segment_command* sh = (struct segment_command*)cmd;
+    if (sh->cmd != LC_SEGMENT) {
+      continue;
+    }
+    if (end < sh->fileoff + sh->filesize) {
+      end = sh->fileoff + sh->filesize;
+    }
+    cmd += sh->cmdsize;
+  }
+  // Let the kernel read ahead what the dynamic loader is going to
+  // map in memory soon after.
+  if (end > 0) {
+    ReadAhead(buf.getFd(), base - buf, end);
+  }
+#endif
+}
+
+void
+mozilla::ReadAheadFile(mozilla::pathstr_t aFilePath, const size_t aOffset,
+                       const size_t aCount, mozilla::filedesc_t* aOutFd)
+{
+#if defined(XP_WIN)
+  if (!aFilePath) {
+    if (aOutFd) {
+      *aOutFd = INVALID_HANDLE_VALUE;
+    }
+    return;
+  }
+  HANDLE fd = CreateFileW(aFilePath, GENERIC_READ, FILE_SHARE_READ, nullptr,
+                          OPEN_EXISTING, FILE_FLAG_SEQUENTIAL_SCAN, nullptr);
+  if (aOutFd) {
+    *aOutFd = fd;
+  }
+  if (fd == INVALID_HANDLE_VALUE) {
+    return;
+  }
+  ReadAhead(fd, aOffset, aCount);
+  if (!aOutFd) {
+    CloseHandle(fd);
+  }
+#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX)
+  if (!aFilePath) {
+    if (aOutFd) {
+      *aOutFd = -1;
+    }
+    return;
+  }
+  int fd = open(aFilePath, O_RDONLY);
+  if (aOutFd) {
+    *aOutFd = fd;
+  }
+  if (fd < 0) {
+    return;
+  }
+  size_t count;
+  if (aCount == SIZE_MAX) {
+    struct stat st;
+    if (fstat(fd, &st) < 0) {
+      if (!aOutFd) {
+        close(fd);
+      }
+      return;
+    }
+    count = st.st_size;
+  } else {
+    count = aCount;
+  }
+  ReadAhead(fd, aOffset, count);
+  if (!aOutFd) {
+    close(fd);
+  }
+#endif
+}
+
diff --git a/xpcom/glue/FileUtils.h b/xpcom/glue/FileUtils.h
new file mode 100644
index 0000000000..aaf912b21b
--- /dev/null
+++ b/xpcom/glue/FileUtils.h
@@ -0,0 +1,220 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_FileUtils_h
+#define mozilla_FileUtils_h
+
+#include "nscore.h" // nullptr
+
+#if defined(XP_UNIX)
+# include <unistd.h>
+#elif defined(XP_WIN)
+# include <io.h>
+#endif
+#include "prio.h"
+
+#include "mozilla/Scoped.h"
+#include "nsIFile.h"
+#include <errno.h>
+#include <limits.h>
+
+namespace mozilla {
+
+#if defined(XP_WIN)
+typedef void* filedesc_t;
+typedef const wchar_t* pathstr_t;
+#else
+typedef int filedesc_t;
+typedef const char* pathstr_t;
+#endif
+
+/**
+ * ScopedCloseFD is a RAII wrapper for POSIX file descriptors
+ *
+ * Instances |close()| their fds when they go out of scope.
+ */
+struct ScopedCloseFDTraits
+{
+  typedef int type;
+  static type empty() { return -1; }
+  static void release(type aFd)
+  {
+    if (aFd != -1) {
+      while (close(aFd) == -1 && errno == EINTR) {
+      }
+    }
+  }
+};
+typedef Scoped<ScopedCloseFDTraits> ScopedClose;
+
+#if !defined(XPCOM_GLUE)
+
+/**
+ * AutoFDClose is a RAII wrapper for PRFileDesc.
+ *
+ * Instances |PR_Close| their fds when they go out of scope.
+ **/
+struct ScopedClosePRFDTraits
+{
+  typedef PRFileDesc* type;
+  static type empty() { return nullptr; }
+  static void release(type aFd)
+  {
+    if (aFd) {
+      PR_Close(aFd);
+    }
+  }
+};
+typedef Scoped<ScopedClosePRFDTraits> AutoFDClose;
+
+/* RAII wrapper for FILE descriptors */
+struct ScopedCloseFileTraits
+{
+  typedef FILE* type;
+  static type empty() { return nullptr; }
+  static void release(type aFile)
+  {
+    if (aFile) {
+      fclose(aFile);
+    }
+  }
+};
+typedef Scoped<ScopedCloseFileTraits> ScopedCloseFile;
+
+/**
+ * Fallocate efficiently and continuously allocates files via fallocate-type APIs.
+ * This is useful for avoiding fragmentation.
+ * On sucess the file be padded with zeros to grow to aLength.
+ *
+ * @param aFD file descriptor.
+ * @param aLength length of file to grow to.
+ * @return true on success.
+ */
+bool fallocate(PRFileDesc* aFD, int64_t aLength);
+
+/**
+ * Use readahead to preload shared libraries into the file cache before loading.
+ * WARNING: This function should not be used without a telemetry field trial
+ *          demonstrating a clear performance improvement!
+ *
+ * @param aFile nsIFile representing path to shared library
+ */
+void ReadAheadLib(nsIFile* aFile);
+
+/**
+ * Use readahead to preload a file into the file cache before reading.
+ * WARNING: This function should not be used without a telemetry field trial
+ *          demonstrating a clear performance improvement!
+ *
+ * @param aFile nsIFile representing path to shared library
+ * @param aOffset Offset into the file to begin preloading
+ * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
+ * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will
+ *        return its internal, opened file descriptor instead of closing it.
+ */
+void ReadAheadFile(nsIFile* aFile, const size_t aOffset = 0,
+                   const size_t aCount = SIZE_MAX,
+                   filedesc_t* aOutFd = nullptr);
+
+#endif // !defined(XPCOM_GLUE)
+
+/**
+ * Use readahead to preload shared libraries into the file cache before loading.
+ * WARNING: This function should not be used without a telemetry field trial
+ *          demonstrating a clear performance improvement!
+ *
+ * @param aFilePath path to shared library
+ */
+void ReadAheadLib(pathstr_t aFilePath);
+
+/**
+ * Use readahead to preload a file into the file cache before loading.
+ * WARNING: This function should not be used without a telemetry field trial
+ *          demonstrating a clear performance improvement!
+ *
+ * @param aFilePath path to shared library
+ * @param aOffset Offset into the file to begin preloading
+ * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
+ * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will
+ *        return its internal, opened file descriptor instead of closing it.
+ */
+void ReadAheadFile(pathstr_t aFilePath, const size_t aOffset = 0,
+                   const size_t aCount = SIZE_MAX,
+                   filedesc_t* aOutFd = nullptr);
+
+/**
+ * Use readahead to preload a file into the file cache before reading.
+ * When this function exits, the file pointer is guaranteed to be in the same
+ * position it was in before this function was called.
+ * WARNING: This function should not be used without a telemetry field trial
+ *          demonstrating a clear performance improvement!
+ *
+ * @param aFd file descriptor opened for read access
+ * (on Windows, file must be opened with FILE_FLAG_SEQUENTIAL_SCAN)
+ * @param aOffset Offset into the file to begin preloading
+ * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
+ */
+void ReadAhead(filedesc_t aFd, const size_t aOffset = 0,
+               const size_t aCount = SIZE_MAX);
+
+
+#if defined(MOZ_WIDGET_GONK) || defined(XP_UNIX)
+#define MOZ_TEMP_FAILURE_RETRY(exp) (__extension__({ \
+  typeof (exp) _rc; \
+  do { \
+    _rc = (exp); \
+  } while (_rc == -1 && errno == EINTR); \
+  _rc; \
+}))
+#endif
+
+/* Define ReadSysFile() and WriteSysFile() only on GONK to avoid unnecessary
+ * libxul bloat. Also define it in debug builds, so that unit tests for it can
+ * be written and run in non-GONK builds. */
+#if (defined(MOZ_WIDGET_GONK) || defined(DEBUG)) && defined(XP_UNIX)
+
+#ifndef ReadSysFile_PRESENT
+#define ReadSysFile_PRESENT
+#endif /* ReadSysFile_PRESENT */
+
+#ifndef WriteSysFile_PRESENT
+#define WriteSysFile_PRESENT
+#endif /* WriteSysFile_PRESENT */
+
+/**
+ * Read the contents of a file.
+ * This function is intended for reading a single-lined text files from
+ * /sys/. If the file ends with a newline ('\n') then it will be discarded.
+ * The output buffer will always be '\0'-terminated on successful completion.
+ * If aBufSize == 0, then this function will return true if the file exists
+ * and is readable (it will not attempt to read anything from it).
+ * On failure the contents of aBuf after this call will be undefined and the
+ * value of the global variable errno will be set accordingly.
+ * @return true on success, notice that less than requested bytes could have
+ * been read if the file was smaller
+ */
+bool ReadSysFile(const char* aFilename, char* aBuf, size_t aBufSize);
+
+/**
+ * Parse the contents of a file, assuming it contains a decimal integer.
+ * @return true on success
+ */
+bool ReadSysFile(const char* aFilename, int* aVal);
+
+/**
+ * Parse the contents of a file, assuming it contains a boolean value
+ * (either 0 or 1).
+ * @return true on success
+ */
+bool ReadSysFile(const char* aFilename, bool* aVal);
+
+bool WriteSysFile(const char* aFilename, const char* aBuf);
+
+#endif /* (MOZ_WIDGET_GONK || DEBUG) && XP_UNIX */
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/glue/GenericFactory.cpp b/xpcom/glue/GenericFactory.cpp
new file mode 100644
index 0000000000..5bf0b97a4f
--- /dev/null
+++ b/xpcom/glue/GenericFactory.cpp
@@ -0,0 +1,27 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/GenericFactory.h"
+
+namespace mozilla {
+
+NS_IMPL_ISUPPORTS(GenericFactory, nsIFactory)
+
+NS_IMETHODIMP
+GenericFactory::CreateInstance(nsISupports* aOuter, REFNSIID aIID,
+                               void** aResult)
+{
+  return mCtor(aOuter, aIID, aResult);
+}
+
+NS_IMETHODIMP
+GenericFactory::LockFactory(bool aLock)
+{
+  NS_ERROR("Vestigial method, never called!");
+  return NS_ERROR_FAILURE;
+}
+
+} // namespace mozilla
diff --git a/xpcom/glue/GenericFactory.h b/xpcom/glue/GenericFactory.h
new file mode 100644
index 0000000000..4561f2a2d0
--- /dev/null
+++ b/xpcom/glue/GenericFactory.h
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_GenericFactory_h
+#define mozilla_GenericFactory_h
+
+#include "mozilla/Attributes.h"
+
+#include "mozilla/Module.h"
+
+namespace mozilla {
+
+/**
+ * A generic factory which uses a constructor function to create instances.
+ * This class is intended for use by the component manager and the generic
+ * module.
+ */
+class GenericFactory final : public nsIFactory
+{
+  ~GenericFactory() {}
+
+public:
+  typedef Module::ConstructorProcPtr ConstructorProcPtr;
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIFACTORY
+
+  explicit GenericFactory(ConstructorProcPtr aCtor)
+    : mCtor(aCtor)
+  {
+    NS_ASSERTION(mCtor, "GenericFactory with no constructor");
+  }
+
+private:
+  ConstructorProcPtr mCtor;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_GenericFactory_h
diff --git a/xpcom/glue/GenericModule.cpp b/xpcom/glue/GenericModule.cpp
new file mode 100644
index 0000000000..0b5cd3a7c2
--- /dev/null
+++ b/xpcom/glue/GenericModule.cpp
@@ -0,0 +1,98 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ModuleUtils.h"
+#include "mozilla/GenericFactory.h"
+
+#include "nsICategoryManager.h"
+#include "nsIComponentManager.h"
+#include "nsIComponentRegistrar.h"
+#include "nsServiceManagerUtils.h"
+#include "nsXPCOMCID.h"
+#include "nsStringAPI.h"
+
+namespace mozilla {
+
+NS_IMPL_ISUPPORTS(GenericModule, nsIModule)
+
+NS_IMETHODIMP
+GenericModule::GetClassObject(nsIComponentManager* aCompMgr,
+                              const nsCID& aCID,
+                              const nsIID& aIID,
+                              void** aResult)
+{
+  for (const Module::CIDEntry* e = mData->mCIDs; e->cid; ++e) {
+    if (e->cid->Equals(aCID)) {
+      nsCOMPtr<nsIFactory> f;
+      if (e->getFactoryProc) {
+        f = e->getFactoryProc(*mData, *e);
+      } else {
+        NS_ASSERTION(e->constructorProc, "No constructor proc?");
+        f = new GenericFactory(e->constructorProc);
+      }
+      if (!f) {
+        return NS_ERROR_FAILURE;
+      }
+
+      return f->QueryInterface(aIID, aResult);
+    }
+  }
+  NS_ERROR("Asking a module for a CID it doesn't implement.");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericModule::RegisterSelf(nsIComponentManager* aCompMgr,
+                            nsIFile* aLocation,
+                            const char* aLoaderStr,
+                            const char* aType)
+{
+  nsCOMPtr<nsIComponentRegistrar> registrar = do_QueryInterface(aCompMgr);
+  for (const Module::CIDEntry* e = mData->mCIDs; e->cid; ++e) {
+    registrar->RegisterFactoryLocation(*e->cid, "", nullptr, aLocation,
+                                       aLoaderStr, aType);
+  }
+
+  for (const Module::ContractIDEntry* e = mData->mContractIDs;
+       e && e->contractid;
+       ++e) {
+    registrar->RegisterFactoryLocation(*e->cid, "", e->contractid, aLocation,
+                                       aLoaderStr, aType);
+  }
+
+  nsCOMPtr<nsICategoryManager> catman;
+  for (const Module::CategoryEntry* e = mData->mCategoryEntries;
+       e && e->category;
+       ++e) {
+    if (!catman) {
+      catman = do_GetService(NS_CATEGORYMANAGER_CONTRACTID);
+    }
+
+    nsAutoCString prevValue;
+    catman->AddCategoryEntry(e->category, e->entry, e->value, true, true,
+                             getter_Copies(prevValue));
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GenericModule::UnregisterSelf(nsIComponentManager* aCompMgr,
+                              nsIFile* aFile,
+                              const char* aLoaderStr)
+{
+  NS_ERROR("Nobody should ever call UnregisterSelf!");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericModule::CanUnload(nsIComponentManager* aCompMgr, bool* aResult)
+{
+  NS_ERROR("Nobody should ever call CanUnload!");
+  *aResult = false;
+  return NS_OK;
+}
+
+} // namespace mozilla
diff --git a/xpcom/glue/IntentionalCrash.h b/xpcom/glue/IntentionalCrash.h
new file mode 100644
index 0000000000..d01006dff1
--- /dev/null
+++ b/xpcom/glue/IntentionalCrash.h
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <string>
+#include <sstream>
+#include <stdlib.h>
+#include <stdio.h>
+
+#ifdef XP_WIN
+#include <process.h>
+#define getpid _getpid
+#else
+#include <unistd.h>
+#endif
+
+#ifndef mozilla_IntentionalCrash_h
+#define mozilla_IntentionalCrash_h
+
+namespace mozilla {
+
+inline void
+NoteIntentionalCrash(const char* aProcessType)
+{
+  char* f = getenv("XPCOM_MEM_BLOAT_LOG");
+  if (!f) {
+    return;
+  }
+
+  fprintf(stderr, "XPCOM_MEM_BLOAT_LOG: %s\n", f);
+
+  std::string bloatLog(f);
+
+  bool hasExt = false;
+  if (bloatLog.size() >= 4 &&
+      bloatLog.compare(bloatLog.size() - 4, 4, ".log", 4) == 0) {
+    hasExt = true;
+    bloatLog.erase(bloatLog.size() - 4, 4);
+  }
+
+  std::ostringstream bloatName;
+  bloatName << bloatLog << "_" << aProcessType << "_pid" << getpid();
+  if (hasExt) {
+    bloatName << ".log";
+  }
+
+  fprintf(stderr, "Writing to log: %s\n", bloatName.str().c_str());
+
+  FILE* processfd = fopen(bloatName.str().c_str(), "a");
+  fprintf(processfd, "==> process %d will purposefully crash\n", getpid());
+  fclose(processfd);
+}
+
+} // namespace mozilla
+
+#endif // mozilla_IntentionalCrash_h
diff --git a/xpcom/glue/MainThreadUtils.h b/xpcom/glue/MainThreadUtils.h
new file mode 100644
index 0000000000..8d76f84ec5
--- /dev/null
+++ b/xpcom/glue/MainThreadUtils.h
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MainThreadUtils_h_
+#define MainThreadUtils_h_
+
+#include "nscore.h"
+
+class nsIThread;
+
+/**
+ * Get a reference to the main thread.
+ *
+ * @param aResult
+ *   The resulting nsIThread object.
+ */
+extern nsresult NS_GetMainThread(nsIThread** aResult);
+
+#ifdef MOZILLA_INTERNAL_API
+// Fast access to the current thread.  Do not release the returned pointer!  If
+// you want to use this pointer from some other thread, then you will need to
+// AddRef it.  Otherwise, you should only consider this pointer valid from code
+// running on the current thread.
+extern nsIThread* NS_GetCurrentThread();
+#endif
+
+#ifdef MOZILLA_INTERNAL_API
+bool NS_IsMainThread();
+#else
+/**
+ * Test to see if the current thread is the main thread.
+ *
+ * @returns true if the current thread is the main thread, and false
+ * otherwise.
+ */
+extern bool NS_IsMainThread();
+#endif
+
+#endif // MainThreadUtils_h_
diff --git a/xpcom/glue/Monitor.h b/xpcom/glue/Monitor.h
new file mode 100644
index 0000000000..60750acb33
--- /dev/null
+++ b/xpcom/glue/Monitor.h
@@ -0,0 +1,135 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Monitor_h
+#define mozilla_Monitor_h
+
+#include "mozilla/CondVar.h"
+#include "mozilla/Mutex.h"
+
+namespace mozilla {
+
+/**
+ * Monitor provides a *non*-reentrant monitor: *not* a Java-style
+ * monitor.  If your code needs support for reentrancy, use
+ * ReentrantMonitor instead.  (Rarely should reentrancy be needed.)
+ *
+ * Instead of directly calling Monitor methods, it's safer and simpler
+ * to instead use the RAII wrappers MonitorAutoLock and
+ * MonitorAutoUnlock.
+ */
+class Monitor
+{
+public:
+  explicit Monitor(const char* aName)
+    : mMutex(aName)
+    , mCondVar(mMutex, "[Monitor.mCondVar]")
+  {
+  }
+
+  ~Monitor() {}
+
+  void Lock() { mMutex.Lock(); }
+  void Unlock() { mMutex.Unlock(); }
+
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT)
+  {
+    return mCondVar.Wait(aInterval);
+  }
+
+  nsresult Notify() { return mCondVar.Notify(); }
+  nsresult NotifyAll() { return mCondVar.NotifyAll(); }
+
+  void AssertCurrentThreadOwns() const
+  {
+    mMutex.AssertCurrentThreadOwns();
+  }
+
+  void AssertNotCurrentThreadOwns() const
+  {
+    mMutex.AssertNotCurrentThreadOwns();
+  }
+
+private:
+  Monitor();
+  Monitor(const Monitor&);
+  Monitor& operator=(const Monitor&);
+
+  Mutex mMutex;
+  CondVar mCondVar;
+};
+
+/**
+ * Lock the monitor for the lexical scope instances of this class are
+ * bound to (except for MonitorAutoUnlock in nested scopes).
+ *
+ * The monitor must be unlocked when instances of this class are
+ * created.
+ */
+class MOZ_STACK_CLASS MonitorAutoLock
+{
+public:
+  explicit MonitorAutoLock(Monitor& aMonitor)
+    : mMonitor(&aMonitor)
+  {
+    mMonitor->Lock();
+  }
+
+  ~MonitorAutoLock()
+  {
+    mMonitor->Unlock();
+  }
+
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT)
+  {
+    return mMonitor->Wait(aInterval);
+  }
+
+  nsresult Notify() { return mMonitor->Notify(); }
+  nsresult NotifyAll() { return mMonitor->NotifyAll(); }
+
+private:
+  MonitorAutoLock();
+  MonitorAutoLock(const MonitorAutoLock&);
+  MonitorAutoLock& operator=(const MonitorAutoLock&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  Monitor* mMonitor;
+};
+
+/**
+ * Unlock the monitor for the lexical scope instances of this class
+ * are bound to (except for MonitorAutoLock in nested scopes).
+ *
+ * The monitor must be locked by the current thread when instances of
+ * this class are created.
+ */
+class MOZ_STACK_CLASS MonitorAutoUnlock
+{
+public:
+  explicit MonitorAutoUnlock(Monitor& aMonitor)
+    : mMonitor(&aMonitor)
+  {
+    mMonitor->Unlock();
+  }
+
+  ~MonitorAutoUnlock()
+  {
+    mMonitor->Lock();
+  }
+
+private:
+  MonitorAutoUnlock();
+  MonitorAutoUnlock(const MonitorAutoUnlock&);
+  MonitorAutoUnlock& operator=(const MonitorAutoUnlock&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  Monitor* mMonitor;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_Monitor_h
diff --git a/xpcom/glue/Mutex.h b/xpcom/glue/Mutex.h
new file mode 100644
index 0000000000..16ad44f4c1
--- /dev/null
+++ b/xpcom/glue/Mutex.h
@@ -0,0 +1,229 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Mutex_h
+#define mozilla_Mutex_h
+
+#include "prlock.h"
+
+#include "mozilla/BlockingResourceBase.h"
+#include "mozilla/GuardObjects.h"
+
+//
+// Provides:
+//
+//  - Mutex, a non-recursive mutex
+//  - MutexAutoLock, an RAII class for ensuring that Mutexes are properly
+//    locked and unlocked
+//  - MutexAutoUnlock, complementary sibling to MutexAutoLock
+//
+//  - OffTheBooksMutex, a non-recursive mutex that doesn't do leak checking
+//  - OffTheBooksMutexAuto{Lock,Unlock} - Like MutexAuto{Lock,Unlock}, but for
+//    an OffTheBooksMutex.
+//
+// Using MutexAutoLock/MutexAutoUnlock etc. is MUCH preferred to making bare
+// calls to Lock and Unlock.
+//
+namespace mozilla {
+
+/**
+ * OffTheBooksMutex is identical to Mutex, except that OffTheBooksMutex doesn't
+ * include leak checking.  Sometimes you want to intentionally "leak" a mutex
+ * until shutdown; in these cases, OffTheBooksMutex is for you.
+ */
+class OffTheBooksMutex : BlockingResourceBase
+{
+public:
+  /**
+   * @param aName A name which can reference this lock
+   * @returns If failure, nullptr
+   *          If success, a valid Mutex* which must be destroyed
+   *          by Mutex::DestroyMutex()
+   **/
+  explicit OffTheBooksMutex(const char* aName)
+    : BlockingResourceBase(aName, eMutex)
+  {
+    mLock = PR_NewLock();
+    if (!mLock) {
+      NS_RUNTIMEABORT("Can't allocate mozilla::Mutex");
+    }
+  }
+
+  ~OffTheBooksMutex()
+  {
+    NS_ASSERTION(mLock,
+                 "improperly constructed Lock or double free");
+    // NSPR does consistency checks for us
+    PR_DestroyLock(mLock);
+    mLock = 0;
+  }
+
+#ifndef DEBUG
+  /**
+   * Lock
+   * @see prlock.h
+   **/
+  void Lock() { PR_Lock(mLock); }
+
+  /**
+   * Unlock
+   * @see prlock.h
+   **/
+  void Unlock() { PR_Unlock(mLock); }
+
+  /**
+   * AssertCurrentThreadOwns
+   * @see prlock.h
+   **/
+  void AssertCurrentThreadOwns() const {}
+
+  /**
+   * AssertNotCurrentThreadOwns
+   * @see prlock.h
+   **/
+  void AssertNotCurrentThreadOwns() const {}
+
+#else
+  void Lock();
+  void Unlock();
+
+  void AssertCurrentThreadOwns() const
+  {
+    PR_ASSERT_CURRENT_THREAD_OWNS_LOCK(mLock);
+  }
+
+  void AssertNotCurrentThreadOwns() const
+  {
+    // FIXME bug 476536
+  }
+
+#endif  // ifndef DEBUG
+
+private:
+  OffTheBooksMutex();
+  OffTheBooksMutex(const OffTheBooksMutex&);
+  OffTheBooksMutex& operator=(const OffTheBooksMutex&);
+
+  PRLock* mLock;
+
+  friend class CondVar;
+
+  // MozPromise needs to access mLock for debugging purpose.
+  template<typename, typename, bool>
+  friend class MozPromise;
+};
+
+/**
+ * Mutex
+ * When possible, use MutexAutoLock/MutexAutoUnlock to lock/unlock this
+ * mutex within a scope, instead of calling Lock/Unlock directly.
+ */
+class Mutex : public OffTheBooksMutex
+{
+public:
+  explicit Mutex(const char* aName)
+    : OffTheBooksMutex(aName)
+  {
+    MOZ_COUNT_CTOR(Mutex);
+  }
+
+  ~Mutex()
+  {
+    MOZ_COUNT_DTOR(Mutex);
+  }
+
+private:
+  Mutex();
+  Mutex(const Mutex&);
+  Mutex& operator=(const Mutex&);
+};
+
+/**
+ * MutexAutoLock
+ * Acquires the Mutex when it enters scope, and releases it when it leaves
+ * scope.
+ *
+ * MUCH PREFERRED to bare calls to Mutex.Lock and Unlock.
+ */
+template<typename T>
+class MOZ_RAII BaseAutoLock
+{
+public:
+  /**
+   * Constructor
+   * The constructor aquires the given lock.  The destructor
+   * releases the lock.
+   *
+   * @param aLock A valid mozilla::Mutex* returned by
+   *              mozilla::Mutex::NewMutex.
+   **/
+  explicit BaseAutoLock(T& aLock MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+    : mLock(&aLock)
+  {
+    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+    NS_ASSERTION(mLock, "null mutex");
+    mLock->Lock();
+  }
+
+  ~BaseAutoLock(void)
+  {
+    mLock->Unlock();
+  }
+
+private:
+  BaseAutoLock();
+  BaseAutoLock(BaseAutoLock&);
+  BaseAutoLock& operator=(BaseAutoLock&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  T* mLock;
+  MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+};
+
+typedef BaseAutoLock<Mutex> MutexAutoLock;
+typedef BaseAutoLock<OffTheBooksMutex> OffTheBooksMutexAutoLock;
+
+/**
+ * MutexAutoUnlock
+ * Releases the Mutex when it enters scope, and re-acquires it when it leaves
+ * scope.
+ *
+ * MUCH PREFERRED to bare calls to Mutex.Unlock and Lock.
+ */
+template<typename T>
+class MOZ_RAII BaseAutoUnlock
+{
+public:
+  explicit BaseAutoUnlock(T& aLock MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+    : mLock(&aLock)
+  {
+    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+    NS_ASSERTION(mLock, "null lock");
+    mLock->Unlock();
+  }
+
+  ~BaseAutoUnlock()
+  {
+    mLock->Lock();
+  }
+
+private:
+  BaseAutoUnlock();
+  BaseAutoUnlock(BaseAutoUnlock&);
+  BaseAutoUnlock& operator=(BaseAutoUnlock&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  T* mLock;
+  MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+};
+
+typedef BaseAutoUnlock<Mutex> MutexAutoUnlock;
+typedef BaseAutoUnlock<OffTheBooksMutex> OffTheBooksMutexAutoUnlock;
+
+} // namespace mozilla
+
+
+#endif // ifndef mozilla_Mutex_h
diff --git a/xpcom/glue/Observer.h b/xpcom/glue/Observer.h
new file mode 100644
index 0000000000..958e5e4a96
--- /dev/null
+++ b/xpcom/glue/Observer.h
@@ -0,0 +1,83 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Observer_h
+#define mozilla_Observer_h
+
+#include "nsTArray.h"
+
+namespace mozilla {
+
+/**
+ * Observer<T> provides a way for a class to observe something.
+ * When an event has to be broadcasted to all Observer<T>, Notify() method
+ * is called.
+ * T represents the type of the object passed in argument to Notify().
+ *
+ * @see ObserverList.
+ */
+template<class T>
+class Observer
+{
+public:
+  virtual ~Observer() {}
+  virtual void Notify(const T& aParam) = 0;
+};
+
+/**
+ * ObserverList<T> tracks Observer<T> and can notify them when Broadcast() is
+ * called.
+ * T represents the type of the object passed in argument to Broadcast() and
+ * sent to Observer<T> objects through Notify().
+ *
+ * @see Observer.
+ */
+template<class T>
+class ObserverList
+{
+public:
+  /**
+   * Note: When calling AddObserver, it's up to the caller to make sure the
+   * object isn't going to be release as long as RemoveObserver hasn't been
+   * called.
+   *
+   * @see RemoveObserver()
+   */
+  void AddObserver(Observer<T>* aObserver)
+  {
+    mObservers.AppendElement(aObserver);
+  }
+
+  /**
+   * Remove the observer from the observer list.
+   * @return Whether the observer has been found in the list.
+   */
+  bool RemoveObserver(Observer<T>* aObserver)
+  {
+    return mObservers.RemoveElement(aObserver);
+  }
+
+  uint32_t Length()
+  {
+    return mObservers.Length();
+  }
+
+  void Broadcast(const T& aParam)
+  {
+    nsTArray<Observer<T>*> observersCopy(mObservers);
+    uint32_t size = observersCopy.Length();
+    for (uint32_t i = 0; i < size; ++i) {
+      observersCopy[i]->Notify(aParam);
+    }
+  }
+
+protected:
+  nsTArray<Observer<T>*> mObservers;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_Observer_h
diff --git a/xpcom/glue/PLDHashTable.cpp b/xpcom/glue/PLDHashTable.cpp
new file mode 100644
index 0000000000..6152e90003
--- /dev/null
+++ b/xpcom/glue/PLDHashTable.cpp
@@ -0,0 +1,801 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <new>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "PLDHashTable.h"
+#include "mozilla/HashFunctions.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/OperatorNewExtensions.h"
+#include "nsAlgorithm.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/ChaosMode.h"
+
+using namespace mozilla;
+
+#ifdef DEBUG
+
+class AutoReadOp
+{
+  Checker& mChk;
+public:
+  explicit AutoReadOp(Checker& aChk) : mChk(aChk) { mChk.StartReadOp(); }
+  ~AutoReadOp() { mChk.EndReadOp(); }
+};
+
+class AutoWriteOp
+{
+  Checker& mChk;
+public:
+  explicit AutoWriteOp(Checker& aChk) : mChk(aChk) { mChk.StartWriteOp(); }
+  ~AutoWriteOp() { mChk.EndWriteOp(); }
+};
+
+class AutoIteratorRemovalOp
+{
+  Checker& mChk;
+public:
+  explicit AutoIteratorRemovalOp(Checker& aChk)
+    : mChk(aChk)
+  {
+    mChk.StartIteratorRemovalOp();
+  }
+  ~AutoIteratorRemovalOp() { mChk.EndIteratorRemovalOp(); }
+};
+
+class AutoDestructorOp
+{
+  Checker& mChk;
+public:
+  explicit AutoDestructorOp(Checker& aChk)
+    : mChk(aChk)
+  {
+    mChk.StartDestructorOp();
+  }
+  ~AutoDestructorOp() { mChk.EndDestructorOp(); }
+};
+
+#endif
+
+/* static */ PLDHashNumber
+PLDHashTable::HashStringKey(const void* aKey)
+{
+  return HashString(static_cast<const char*>(aKey));
+}
+
+/* static */ PLDHashNumber
+PLDHashTable::HashVoidPtrKeyStub(const void* aKey)
+{
+  return (PLDHashNumber)(ptrdiff_t)aKey >> 2;
+}
+
+/* static */ bool
+PLDHashTable::MatchEntryStub(const PLDHashEntryHdr* aEntry, const void* aKey)
+{
+  const PLDHashEntryStub* stub = (const PLDHashEntryStub*)aEntry;
+
+  return stub->key == aKey;
+}
+
+/* static */ bool
+PLDHashTable::MatchStringKey(const PLDHashEntryHdr* aEntry, const void* aKey)
+{
+  const PLDHashEntryStub* stub = (const PLDHashEntryStub*)aEntry;
+
+  // XXX tolerate null keys on account of sloppy Mozilla callers.
+  return stub->key == aKey ||
+         (stub->key && aKey &&
+          strcmp((const char*)stub->key, (const char*)aKey) == 0);
+}
+
+/* static */ void
+PLDHashTable::MoveEntryStub(PLDHashTable* aTable,
+                            const PLDHashEntryHdr* aFrom,
+                            PLDHashEntryHdr* aTo)
+{
+  memcpy(aTo, aFrom, aTable->mEntrySize);
+}
+
+/* static */ void
+PLDHashTable::ClearEntryStub(PLDHashTable* aTable, PLDHashEntryHdr* aEntry)
+{
+  memset(aEntry, 0, aTable->mEntrySize);
+}
+
+static const PLDHashTableOps gStubOps = {
+  PLDHashTable::HashVoidPtrKeyStub,
+  PLDHashTable::MatchEntryStub,
+  PLDHashTable::MoveEntryStub,
+  PLDHashTable::ClearEntryStub,
+  nullptr
+};
+
+/* static */ const PLDHashTableOps*
+PLDHashTable::StubOps()
+{
+  return &gStubOps;
+}
+
+static bool
+SizeOfEntryStore(uint32_t aCapacity, uint32_t aEntrySize, uint32_t* aNbytes)
+{
+  uint64_t nbytes64 = uint64_t(aCapacity) * uint64_t(aEntrySize);
+  *aNbytes = aCapacity * aEntrySize;
+  return uint64_t(*aNbytes) == nbytes64;   // returns false on overflow
+}
+
+// Compute max and min load numbers (entry counts). We have a secondary max
+// that allows us to overload a table reasonably if it cannot be grown further
+// (i.e. if ChangeTable() fails). The table slows down drastically if the
+// secondary max is too close to 1, but 0.96875 gives only a slight slowdown
+// while allowing 1.3x more elements.
+static inline uint32_t
+MaxLoad(uint32_t aCapacity)
+{
+  return aCapacity - (aCapacity >> 2);  // == aCapacity * 0.75
+}
+static inline uint32_t
+MaxLoadOnGrowthFailure(uint32_t aCapacity)
+{
+  return aCapacity - (aCapacity >> 5);  // == aCapacity * 0.96875
+}
+static inline uint32_t
+MinLoad(uint32_t aCapacity)
+{
+  return aCapacity >> 2;                // == aCapacity * 0.25
+}
+
+// Compute the minimum capacity (and the Log2 of that capacity) for a table
+// containing |aLength| elements while respecting the following contraints:
+// - table must be at most 75% full;
+// - capacity must be a power of two;
+// - capacity cannot be too small.
+static inline void
+BestCapacity(uint32_t aLength, uint32_t* aCapacityOut,
+             uint32_t* aLog2CapacityOut)
+{
+  // Compute the smallest capacity allowing |aLength| elements to be inserted
+  // without rehashing.
+  uint32_t capacity = (aLength * 4 + (3 - 1)) / 3; // == ceil(aLength * 4 / 3)
+  if (capacity < PLDHashTable::kMinCapacity) {
+    capacity = PLDHashTable::kMinCapacity;
+  }
+
+  // Round up capacity to next power-of-two.
+  uint32_t log2 = CeilingLog2(capacity);
+  capacity = 1u << log2;
+  MOZ_ASSERT(capacity <= PLDHashTable::kMaxCapacity);
+
+  *aCapacityOut = capacity;
+  *aLog2CapacityOut = log2;
+}
+
+/* static */ MOZ_ALWAYS_INLINE uint32_t
+PLDHashTable::HashShift(uint32_t aEntrySize, uint32_t aLength)
+{
+  if (aLength > kMaxInitialLength) {
+    MOZ_CRASH("Initial length is too large");
+  }
+
+  uint32_t capacity, log2;
+  BestCapacity(aLength, &capacity, &log2);
+
+  uint32_t nbytes;
+  if (!SizeOfEntryStore(capacity, aEntrySize, &nbytes)) {
+    MOZ_CRASH("Initial entry store size is too large");
+  }
+
+  // Compute the hashShift value.
+  return kHashBits - log2;
+}
+
+PLDHashTable::PLDHashTable(const PLDHashTableOps* aOps, uint32_t aEntrySize,
+                           uint32_t aLength)
+  : mOps(aOps)
+  , mHashShift(HashShift(aEntrySize, aLength))
+  , mEntrySize(aEntrySize)
+  , mEntryCount(0)
+  , mRemovedCount(0)
+  , mEntryStore()
+#ifdef DEBUG
+  , mChecker()
+#endif
+{
+}
+
+PLDHashTable&
+PLDHashTable::operator=(PLDHashTable&& aOther)
+{
+  if (this == &aOther) {
+    return *this;
+  }
+
+  // Destruct |this|.
+  this->~PLDHashTable();
+
+  // |mOps| and |mEntrySize| are const so we can't assign them. Instead, we
+  // require that they are equal. The justification for this is that they're
+  // conceptually part of the type -- indeed, if PLDHashTable was a templated
+  // type like nsTHashtable, they *would* be part of the type -- so it only
+  // makes sense to assign in cases where they match.
+  MOZ_RELEASE_ASSERT(mOps == aOther.mOps);
+  MOZ_RELEASE_ASSERT(mEntrySize == aOther.mEntrySize);
+
+  // Move non-const pieces over.
+  mHashShift = Move(aOther.mHashShift);
+  mEntryCount = Move(aOther.mEntryCount);
+  mRemovedCount = Move(aOther.mRemovedCount);
+  mEntryStore = Move(aOther.mEntryStore);
+#ifdef DEBUG
+  mChecker = Move(aOther.mChecker);
+#endif
+
+  // Clear up |aOther| so its destruction will be a no-op.
+  {
+#ifdef DEBUG
+    AutoDestructorOp op(mChecker);
+#endif
+    aOther.mEntryStore.Set(nullptr);
+  }
+
+  return *this;
+}
+
+PLDHashNumber
+PLDHashTable::Hash1(PLDHashNumber aHash0)
+{
+  return aHash0 >> mHashShift;
+}
+
+// Double hashing needs the second hash code to be relatively prime to table
+// size, so we simply make hash2 odd.
+void
+PLDHashTable::Hash2(PLDHashNumber aHash,
+                    uint32_t& aHash2Out, uint32_t& aSizeMaskOut)
+{
+  uint32_t sizeLog2 = kHashBits - mHashShift;
+  aHash2Out = ((aHash << sizeLog2) >> mHashShift) | 1;
+  aSizeMaskOut = (PLDHashNumber(1) << sizeLog2) - 1;
+}
+
+// Reserve mKeyHash 0 for free entries and 1 for removed-entry sentinels. Note
+// that a removed-entry sentinel need be stored only if the removed entry had
+// a colliding entry added after it. Therefore we can use 1 as the collision
+// flag in addition to the removed-entry sentinel value. Multiplicative hash
+// uses the high order bits of mKeyHash, so this least-significant reservation
+// should not hurt the hash function's effectiveness much.
+
+// Match an entry's mKeyHash against an unstored one computed from a key.
+/* static */ bool
+PLDHashTable::MatchEntryKeyhash(PLDHashEntryHdr* aEntry, PLDHashNumber aKeyHash)
+{
+  return (aEntry->mKeyHash & ~kCollisionFlag) == aKeyHash;
+}
+
+// Compute the address of the indexed entry in table.
+PLDHashEntryHdr*
+PLDHashTable::AddressEntry(uint32_t aIndex)
+{
+  return reinterpret_cast<PLDHashEntryHdr*>(
+    mEntryStore.Get() + aIndex * mEntrySize);
+}
+
+PLDHashTable::~PLDHashTable()
+{
+#ifdef DEBUG
+  AutoDestructorOp op(mChecker);
+#endif
+
+  if (!mEntryStore.Get()) {
+    return;
+  }
+
+  // Clear any remaining live entries.
+  char* entryAddr = mEntryStore.Get();
+  char* entryLimit = entryAddr + Capacity() * mEntrySize;
+  while (entryAddr < entryLimit) {
+    PLDHashEntryHdr* entry = (PLDHashEntryHdr*)entryAddr;
+    if (EntryIsLive(entry)) {
+      mOps->clearEntry(this, entry);
+    }
+    entryAddr += mEntrySize;
+  }
+
+  // Entry storage is freed last, by ~EntryStore().
+}
+
+void
+PLDHashTable::ClearAndPrepareForLength(uint32_t aLength)
+{
+  // Get these values before the destructor clobbers them.
+  const PLDHashTableOps* ops = mOps;
+  uint32_t entrySize = mEntrySize;
+
+  this->~PLDHashTable();
+  new (KnownNotNull, this) PLDHashTable(ops, entrySize, aLength);
+}
+
+void
+PLDHashTable::Clear()
+{
+  ClearAndPrepareForLength(kDefaultInitialLength);
+}
+
+// If |Reason| is |ForAdd|, the return value is always non-null and it may be
+// a previously-removed entry. If |Reason| is |ForSearchOrRemove|, the return
+// value is null on a miss, and will never be a previously-removed entry on a
+// hit. This distinction is a bit grotty but this function is hot enough that
+// these differences are worthwhile.
+template <PLDHashTable::SearchReason Reason>
+PLDHashEntryHdr* NS_FASTCALL
+PLDHashTable::SearchTable(const void* aKey, PLDHashNumber aKeyHash)
+{
+  MOZ_ASSERT(mEntryStore.Get());
+  NS_ASSERTION(!(aKeyHash & kCollisionFlag),
+               "!(aKeyHash & kCollisionFlag)");
+
+  // Compute the primary hash address.
+  PLDHashNumber hash1 = Hash1(aKeyHash);
+  PLDHashEntryHdr* entry = AddressEntry(hash1);
+
+  // Miss: return space for a new entry.
+  if (EntryIsFree(entry)) {
+    return (Reason == ForAdd) ? entry : nullptr;
+  }
+
+  // Hit: return entry.
+  PLDHashMatchEntry matchEntry = mOps->matchEntry;
+  if (MatchEntryKeyhash(entry, aKeyHash) &&
+      matchEntry(entry, aKey)) {
+    return entry;
+  }
+
+  // Collision: double hash.
+  PLDHashNumber hash2;
+  uint32_t sizeMask;
+  Hash2(aKeyHash, hash2, sizeMask);
+
+  // Save the first removed entry pointer so Add() can recycle it. (Only used
+  // if Reason==ForAdd.)
+  PLDHashEntryHdr* firstRemoved = nullptr;
+
+  for (;;) {
+    if (Reason == ForAdd) {
+      if (MOZ_UNLIKELY(EntryIsRemoved(entry))) {
+        if (!firstRemoved) {
+          firstRemoved = entry;
+        }
+      } else {
+        entry->mKeyHash |= kCollisionFlag;
+      }
+    }
+
+    hash1 -= hash2;
+    hash1 &= sizeMask;
+
+    entry = AddressEntry(hash1);
+    if (EntryIsFree(entry)) {
+      return (Reason == ForAdd) ? (firstRemoved ? firstRemoved : entry)
+                                : nullptr;
+    }
+
+    if (MatchEntryKeyhash(entry, aKeyHash) &&
+        matchEntry(entry, aKey)) {
+      return entry;
+    }
+  }
+
+  // NOTREACHED
+  return nullptr;
+}
+
+// This is a copy of SearchTable(), used by ChangeTable(), hardcoded to
+//   1. assume |Reason| is |ForAdd|,
+//   2. assume that |aKey| will never match an existing entry, and
+//   3. assume that no entries have been removed from the current table
+//      structure.
+// Avoiding the need for |aKey| means we can avoid needing a way to map entries
+// to keys, which means callers can use complex key types more easily.
+MOZ_ALWAYS_INLINE PLDHashEntryHdr*
+PLDHashTable::FindFreeEntry(PLDHashNumber aKeyHash)
+{
+  MOZ_ASSERT(mEntryStore.Get());
+  NS_ASSERTION(!(aKeyHash & kCollisionFlag),
+               "!(aKeyHash & kCollisionFlag)");
+
+  // Compute the primary hash address.
+  PLDHashNumber hash1 = Hash1(aKeyHash);
+  PLDHashEntryHdr* entry = AddressEntry(hash1);
+
+  // Miss: return space for a new entry.
+  if (EntryIsFree(entry)) {
+    return entry;
+  }
+
+  // Collision: double hash.
+  PLDHashNumber hash2;
+  uint32_t sizeMask;
+  Hash2(aKeyHash, hash2, sizeMask);
+
+  for (;;) {
+    NS_ASSERTION(!EntryIsRemoved(entry),
+                 "!EntryIsRemoved(entry)");
+    entry->mKeyHash |= kCollisionFlag;
+
+    hash1 -= hash2;
+    hash1 &= sizeMask;
+
+    entry = AddressEntry(hash1);
+    if (EntryIsFree(entry)) {
+      return entry;
+    }
+  }
+
+  // NOTREACHED
+}
+
+bool
+PLDHashTable::ChangeTable(int32_t aDeltaLog2)
+{
+  MOZ_ASSERT(mEntryStore.Get());
+
+  // Look, but don't touch, until we succeed in getting new entry store.
+  int32_t oldLog2 = kHashBits - mHashShift;
+  int32_t newLog2 = oldLog2 + aDeltaLog2;
+  uint32_t newCapacity = 1u << newLog2;
+  if (newCapacity > kMaxCapacity) {
+    return false;
+  }
+
+  uint32_t nbytes;
+  if (!SizeOfEntryStore(newCapacity, mEntrySize, &nbytes)) {
+    return false;   // overflowed
+  }
+
+  char* newEntryStore = (char*)malloc(nbytes);
+  if (!newEntryStore) {
+    return false;
+  }
+
+  // We can't fail from here on, so update table parameters.
+  mHashShift = kHashBits - newLog2;
+  mRemovedCount = 0;
+
+  // Assign the new entry store to table.
+  memset(newEntryStore, 0, nbytes);
+  char* oldEntryStore;
+  char* oldEntryAddr;
+  oldEntryAddr = oldEntryStore = mEntryStore.Get();
+  mEntryStore.Set(newEntryStore);
+  PLDHashMoveEntry moveEntry = mOps->moveEntry;
+
+  // Copy only live entries, leaving removed ones behind.
+  uint32_t oldCapacity = 1u << oldLog2;
+  for (uint32_t i = 0; i < oldCapacity; ++i) {
+    PLDHashEntryHdr* oldEntry = (PLDHashEntryHdr*)oldEntryAddr;
+    if (EntryIsLive(oldEntry)) {
+      oldEntry->mKeyHash &= ~kCollisionFlag;
+      PLDHashEntryHdr* newEntry = FindFreeEntry(oldEntry->mKeyHash);
+      NS_ASSERTION(EntryIsFree(newEntry), "EntryIsFree(newEntry)");
+      moveEntry(this, oldEntry, newEntry);
+      newEntry->mKeyHash = oldEntry->mKeyHash;
+    }
+    oldEntryAddr += mEntrySize;
+  }
+
+  free(oldEntryStore);
+  return true;
+}
+
+MOZ_ALWAYS_INLINE PLDHashNumber
+PLDHashTable::ComputeKeyHash(const void* aKey)
+{
+  MOZ_ASSERT(mEntryStore.Get());
+
+  PLDHashNumber keyHash = mOps->hashKey(aKey);
+  keyHash *= kGoldenRatio;
+
+  // Avoid 0 and 1 hash codes, they indicate free and removed entries.
+  if (keyHash < 2) {
+    keyHash -= 2;
+  }
+  keyHash &= ~kCollisionFlag;
+
+  return keyHash;
+}
+
+PLDHashEntryHdr*
+PLDHashTable::Search(const void* aKey)
+{
+#ifdef DEBUG
+  AutoReadOp op(mChecker);
+#endif
+
+  PLDHashEntryHdr* entry = mEntryStore.Get()
+                         ? SearchTable<ForSearchOrRemove>(aKey,
+                                                          ComputeKeyHash(aKey))
+                         : nullptr;
+  return entry;
+}
+
+PLDHashEntryHdr*
+PLDHashTable::Add(const void* aKey, const mozilla::fallible_t&)
+{
+#ifdef DEBUG
+  AutoWriteOp op(mChecker);
+#endif
+
+  // Allocate the entry storage if it hasn't already been allocated.
+  if (!mEntryStore.Get()) {
+    uint32_t nbytes;
+    // We already checked this in the constructor, so it must still be true.
+    MOZ_RELEASE_ASSERT(SizeOfEntryStore(CapacityFromHashShift(), mEntrySize,
+                                        &nbytes));
+    mEntryStore.Set((char*)malloc(nbytes));
+    if (!mEntryStore.Get()) {
+      return nullptr;
+    }
+    memset(mEntryStore.Get(), 0, nbytes);
+  }
+
+  // If alpha is >= .75, grow or compress the table. If aKey is already in the
+  // table, we may grow once more than necessary, but only if we are on the
+  // edge of being overloaded.
+  uint32_t capacity = Capacity();
+  if (mEntryCount + mRemovedCount >= MaxLoad(capacity)) {
+    // Compress if a quarter or more of all entries are removed.
+    int deltaLog2;
+    if (mRemovedCount >= capacity >> 2) {
+      deltaLog2 = 0;
+    } else {
+      deltaLog2 = 1;
+    }
+
+    // Grow or compress the table. If ChangeTable() fails, allow overloading up
+    // to the secondary max. Once we hit the secondary max, return null.
+    if (!ChangeTable(deltaLog2) &&
+        mEntryCount + mRemovedCount >= MaxLoadOnGrowthFailure(capacity)) {
+      return nullptr;
+    }
+  }
+
+  // Look for entry after possibly growing, so we don't have to add it,
+  // then skip it while growing the table and re-add it after.
+  PLDHashNumber keyHash = ComputeKeyHash(aKey);
+  PLDHashEntryHdr* entry = SearchTable<ForAdd>(aKey, keyHash);
+  if (!EntryIsLive(entry)) {
+    // Initialize the entry, indicating that it's no longer free.
+    if (EntryIsRemoved(entry)) {
+      mRemovedCount--;
+      keyHash |= kCollisionFlag;
+    }
+    if (mOps->initEntry) {
+      mOps->initEntry(entry, aKey);
+    }
+    entry->mKeyHash = keyHash;
+    mEntryCount++;
+  }
+
+  return entry;
+}
+
+PLDHashEntryHdr*
+PLDHashTable::Add(const void* aKey)
+{
+  PLDHashEntryHdr* entry = Add(aKey, fallible);
+  if (!entry) {
+    if (!mEntryStore.Get()) {
+      // We OOM'd while allocating the initial entry storage.
+      uint32_t nbytes;
+      (void) SizeOfEntryStore(CapacityFromHashShift(), mEntrySize, &nbytes);
+      NS_ABORT_OOM(nbytes);
+    } else {
+      // We failed to resize the existing entry storage, either due to OOM or
+      // because we exceeded the maximum table capacity or size; report it as
+      // an OOM. The multiplication by 2 gets us the size we tried to allocate,
+      // which is double the current size.
+      NS_ABORT_OOM(2 * EntrySize() * EntryCount());
+    }
+  }
+  return entry;
+}
+
+void
+PLDHashTable::Remove(const void* aKey)
+{
+#ifdef DEBUG
+  AutoWriteOp op(mChecker);
+#endif
+
+  PLDHashEntryHdr* entry = mEntryStore.Get()
+                         ? SearchTable<ForSearchOrRemove>(aKey,
+                                                          ComputeKeyHash(aKey))
+                         : nullptr;
+  if (entry) {
+    RawRemove(entry);
+    ShrinkIfAppropriate();
+  }
+}
+
+void
+PLDHashTable::RemoveEntry(PLDHashEntryHdr* aEntry)
+{
+#ifdef DEBUG
+  AutoWriteOp op(mChecker);
+#endif
+
+  RawRemove(aEntry);
+  ShrinkIfAppropriate();
+}
+
+void
+PLDHashTable::RawRemove(PLDHashEntryHdr* aEntry)
+{
+  // Unfortunately, we can only do weak checking here. That's because
+  // RawRemove() can be called legitimately while an Enumerate() call is
+  // active, which doesn't fit well into how Checker's mState variable works.
+  MOZ_ASSERT(mChecker.IsWritable());
+
+  MOZ_ASSERT(mEntryStore.Get());
+
+  MOZ_ASSERT(EntryIsLive(aEntry), "EntryIsLive(aEntry)");
+
+  // Load keyHash first in case clearEntry() goofs it.
+  PLDHashNumber keyHash = aEntry->mKeyHash;
+  mOps->clearEntry(this, aEntry);
+  if (keyHash & kCollisionFlag) {
+    MarkEntryRemoved(aEntry);
+    mRemovedCount++;
+  } else {
+    MarkEntryFree(aEntry);
+  }
+  mEntryCount--;
+}
+
+// Shrink or compress if a quarter or more of all entries are removed, or if the
+// table is underloaded according to the minimum alpha, and is not minimal-size
+// already.
+void
+PLDHashTable::ShrinkIfAppropriate()
+{
+  uint32_t capacity = Capacity();
+  if (mRemovedCount >= capacity >> 2 ||
+      (capacity > kMinCapacity && mEntryCount <= MinLoad(capacity))) {
+    uint32_t log2;
+    BestCapacity(mEntryCount, &capacity, &log2);
+
+    int32_t deltaLog2 = log2 - (kHashBits - mHashShift);
+    MOZ_ASSERT(deltaLog2 <= 0);
+
+    (void) ChangeTable(deltaLog2);
+  }
+}
+
+size_t
+PLDHashTable::ShallowSizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+{
+#ifdef DEBUG
+  AutoReadOp op(mChecker);
+#endif
+
+  return aMallocSizeOf(mEntryStore.Get());
+}
+
+size_t
+PLDHashTable::ShallowSizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf);
+}
+
+PLDHashTable::Iterator::Iterator(Iterator&& aOther)
+  : mTable(aOther.mTable)
+  , mStart(aOther.mStart)
+  , mLimit(aOther.mLimit)
+  , mCurrent(aOther.mCurrent)
+  , mNexts(aOther.mNexts)
+  , mNextsLimit(aOther.mNextsLimit)
+  , mHaveRemoved(aOther.mHaveRemoved)
+{
+  // No need to change |mChecker| here.
+  aOther.mTable = nullptr;
+  aOther.mStart = nullptr;
+  aOther.mLimit = nullptr;
+  aOther.mCurrent = nullptr;
+  aOther.mNexts = 0;
+  aOther.mNextsLimit = 0;
+  aOther.mHaveRemoved = false;
+}
+
+PLDHashTable::Iterator::Iterator(PLDHashTable* aTable)
+  : mTable(aTable)
+  , mStart(mTable->mEntryStore.Get())
+  , mLimit(mTable->mEntryStore.Get() + mTable->Capacity() * mTable->mEntrySize)
+  , mCurrent(mTable->mEntryStore.Get())
+  , mNexts(0)
+  , mNextsLimit(mTable->EntryCount())
+  , mHaveRemoved(false)
+{
+#ifdef DEBUG
+  mTable->mChecker.StartReadOp();
+#endif
+
+  if (ChaosMode::isActive(ChaosFeature::HashTableIteration) &&
+      mTable->Capacity() > 0) {
+    // Start iterating at a random entry. It would be even more chaotic to
+    // iterate in fully random order, but that's harder.
+    mCurrent += ChaosMode::randomUint32LessThan(mTable->Capacity()) *
+                mTable->mEntrySize;
+  }
+
+  // Advance to the first live entry, if there is one.
+  if (!Done()) {
+    while (IsOnNonLiveEntry()) {
+      MoveToNextEntry();
+    }
+  }
+}
+
+PLDHashTable::Iterator::~Iterator()
+{
+  if (mTable) {
+    if (mHaveRemoved) {
+      mTable->ShrinkIfAppropriate();
+    }
+#ifdef DEBUG
+    mTable->mChecker.EndReadOp();
+#endif
+  }
+}
+
+MOZ_ALWAYS_INLINE bool
+PLDHashTable::Iterator::IsOnNonLiveEntry() const
+{
+  MOZ_ASSERT(!Done());
+  return !EntryIsLive(reinterpret_cast<PLDHashEntryHdr*>(mCurrent));
+}
+
+MOZ_ALWAYS_INLINE void
+PLDHashTable::Iterator::MoveToNextEntry()
+{
+  mCurrent += mTable->mEntrySize;
+  if (mCurrent == mLimit) {
+    mCurrent = mStart;  // Wrap-around. Possible due to Chaos Mode.
+  }
+}
+
+void
+PLDHashTable::Iterator::Next()
+{
+  MOZ_ASSERT(!Done());
+
+  mNexts++;
+
+  // Advance to the next live entry, if there is one.
+  if (!Done()) {
+    do {
+      MoveToNextEntry();
+    } while (IsOnNonLiveEntry());
+  }
+}
+
+void
+PLDHashTable::Iterator::Remove()
+{
+  // This cast is needed for the same reason as the one in the destructor.
+  mTable->RawRemove(Get());
+  mHaveRemoved = true;
+}
+
+#ifdef DEBUG
+void
+PLDHashTable::MarkImmutable()
+{
+  mChecker.SetNonWritable();
+}
+#endif
diff --git a/xpcom/glue/PLDHashTable.h b/xpcom/glue/PLDHashTable.h
new file mode 100644
index 0000000000..cd1323dbe7
--- /dev/null
+++ b/xpcom/glue/PLDHashTable.h
@@ -0,0 +1,621 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef PLDHashTable_h
+#define PLDHashTable_h
+
+#include "mozilla/Atomics.h"
+#include "mozilla/Attributes.h" // for MOZ_ALWAYS_INLINE
+#include "mozilla/fallible.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Move.h"
+#include "mozilla/Types.h"
+#include "nscore.h"
+
+typedef uint32_t PLDHashNumber;
+
+class PLDHashTable;
+struct PLDHashTableOps;
+
+// Table entry header structure.
+//
+// In order to allow in-line allocation of key and value, we do not declare
+// either here. Instead, the API uses const void *key as a formal parameter.
+// The key need not be stored in the entry; it may be part of the value, but
+// need not be stored at all.
+//
+// Callback types are defined below and grouped into the PLDHashTableOps
+// structure, for single static initialization per hash table sub-type.
+//
+// Each hash table sub-type should make its entry type a subclass of
+// PLDHashEntryHdr. The mKeyHash member contains the result of multiplying the
+// hash code returned from the hashKey callback (see below) by kGoldenRatio,
+// then constraining the result to avoid the magic 0 and 1 values. The stored
+// mKeyHash value is table size invariant, and it is maintained automatically
+// -- users need never access it.
+struct PLDHashEntryHdr
+{
+private:
+  friend class PLDHashTable;
+
+  PLDHashNumber mKeyHash;
+};
+
+#ifdef DEBUG
+
+// This class does three kinds of checking:
+//
+// - that calls to one of |mOps| or to an enumerator do not cause re-entry into
+//   the table in an unsafe way;
+//
+// - that multiple threads do not access the table in an unsafe way;
+//
+// - that a table marked as immutable is not modified.
+//
+// "Safe" here means that multiple concurrent read operations are ok, but a
+// write operation (i.e. one that can cause the entry storage to be reallocated
+// or destroyed) cannot safely run concurrently with another read or write
+// operation. This meaning of "safe" is only partial; for example, it does not
+// cover whether a single entry in the table is modified by two separate
+// threads. (Doing such checking would be much harder.)
+//
+// It does this with two variables:
+//
+// - mState, which embodies a tri-stage tagged union with the following
+//   variants:
+//   - Idle
+//   - Read(n), where 'n' is the number of concurrent read operations
+//   - Write
+//
+// - mIsWritable, which indicates if the table is mutable.
+//
+class Checker
+{
+public:
+  constexpr Checker() : mState(kIdle), mIsWritable(1) {}
+
+  Checker& operator=(Checker&& aOther) {
+    // Atomic<> doesn't have an |operator=(Atomic<>&&)|.
+    mState = uint32_t(aOther.mState);
+    mIsWritable = uint32_t(aOther.mIsWritable);
+
+    aOther.mState = kIdle;
+
+    return *this;
+  }
+
+  static bool IsIdle(uint32_t aState)  { return aState == kIdle; }
+  static bool IsRead(uint32_t aState)  { return kRead1 <= aState &&
+                                                aState <= kReadMax; }
+  static bool IsRead1(uint32_t aState) { return aState == kRead1; }
+  static bool IsWrite(uint32_t aState) { return aState == kWrite; }
+
+  bool IsIdle() const { return mState == kIdle; }
+
+  bool IsWritable() const { return !!mIsWritable; }
+
+  void SetNonWritable() { mIsWritable = 0; }
+
+  // NOTE: the obvious way to implement these functions is to (a) check
+  // |mState| is reasonable, and then (b) update |mState|. But the lack of
+  // atomicity in such an implementation can cause problems if we get unlucky
+  // thread interleaving between (a) and (b).
+  //
+  // So instead for |mState| we are careful to (a) first get |mState|'s old
+  // value and assign it a new value in single atomic operation, and only then
+  // (b) check the old value was reasonable. This ensures we don't have
+  // interleaving problems.
+  //
+  // For |mIsWritable| we don't need to be as careful because it can only in
+  // transition in one direction (from writable to non-writable).
+
+  void StartReadOp()
+  {
+    uint32_t oldState = mState++;     // this is an atomic increment
+    MOZ_ASSERT(IsIdle(oldState) || IsRead(oldState));
+    MOZ_ASSERT(oldState < kReadMax);  // check for overflow
+  }
+
+  void EndReadOp()
+  {
+    uint32_t oldState = mState--;     // this is an atomic decrement
+    MOZ_ASSERT(IsRead(oldState));
+  }
+
+  void StartWriteOp()
+  {
+    MOZ_ASSERT(IsWritable());
+    uint32_t oldState = mState.exchange(kWrite);
+    MOZ_ASSERT(IsIdle(oldState));
+  }
+
+  void EndWriteOp()
+  {
+    // Check again that the table is writable, in case it was marked as
+    // non-writable just after the IsWritable() assertion in StartWriteOp()
+    // occurred.
+    MOZ_ASSERT(IsWritable());
+    uint32_t oldState = mState.exchange(kIdle);
+    MOZ_ASSERT(IsWrite(oldState));
+  }
+
+  void StartIteratorRemovalOp()
+  {
+    // When doing removals at the end of iteration, we go from Read1 state to
+    // Write and then back.
+    MOZ_ASSERT(IsWritable());
+    uint32_t oldState = mState.exchange(kWrite);
+    MOZ_ASSERT(IsRead1(oldState));
+  }
+
+  void EndIteratorRemovalOp()
+  {
+    // Check again that the table is writable, in case it was marked as
+    // non-writable just after the IsWritable() assertion in
+    // StartIteratorRemovalOp() occurred.
+    MOZ_ASSERT(IsWritable());
+    uint32_t oldState = mState.exchange(kRead1);
+    MOZ_ASSERT(IsWrite(oldState));
+  }
+
+  void StartDestructorOp()
+  {
+    // A destructor op is like a write, but the table doesn't need to be
+    // writable.
+    uint32_t oldState = mState.exchange(kWrite);
+    MOZ_ASSERT(IsIdle(oldState));
+  }
+
+  void EndDestructorOp()
+  {
+    uint32_t oldState = mState.exchange(kIdle);
+    MOZ_ASSERT(IsWrite(oldState));
+  }
+
+private:
+  // Things of note about the representation of |mState|.
+  // - The values between kRead1..kReadMax represent valid Read(n) values.
+  // - kIdle and kRead1 are deliberately chosen so that incrementing the -
+  //   former gives the latter.
+  // - 9999 concurrent readers should be enough for anybody.
+  static const uint32_t kIdle    = 0;
+  static const uint32_t kRead1   = 1;
+  static const uint32_t kReadMax = 9999;
+  static const uint32_t kWrite   = 10000;
+
+  mutable mozilla::Atomic<uint32_t> mState;
+  mutable mozilla::Atomic<uint32_t> mIsWritable;
+};
+#endif
+
+// A PLDHashTable may be allocated on the stack or within another structure or
+// class. No entry storage is allocated until the first element is added. This
+// means that empty hash tables are cheap, which is good because they are
+// common.
+//
+// There used to be a long, math-heavy comment here about the merits of
+// double hashing vs. chaining; it was removed in bug 1058335. In short, double
+// hashing is more space-efficient unless the element size gets large (in which
+// case you should keep using double hashing but switch to using pointer
+// elements). Also, with double hashing, you can't safely hold an entry pointer
+// and use it after an add or remove operation, unless you sample Generation()
+// before adding or removing, and compare the sample after, dereferencing the
+// entry pointer only if Generation() has not changed.
+class PLDHashTable
+{
+private:
+  // This class maintains the invariant that every time the entry store is
+  // changed, the generation is updated.
+  class EntryStore
+  {
+  private:
+    char* mEntryStore;
+    uint32_t mGeneration;
+
+  public:
+    EntryStore() : mEntryStore(nullptr), mGeneration(0) {}
+
+    ~EntryStore()
+    {
+      free(mEntryStore);
+      mEntryStore = nullptr;
+      mGeneration++;    // a little paranoid, but why not be extra safe?
+    }
+
+    char* Get() { return mEntryStore; }
+    const char* Get() const { return mEntryStore; }
+
+    void Set(char* aEntryStore)
+    {
+      mEntryStore = aEntryStore;
+      mGeneration++;
+    }
+
+    uint32_t Generation() const { return mGeneration; }
+  };
+
+  const PLDHashTableOps* const mOps;  // Virtual operations; see below.
+  int16_t             mHashShift;     // Multiplicative hash shift.
+  const uint32_t      mEntrySize;     // Number of bytes in an entry.
+  uint32_t            mEntryCount;    // Number of entries in table.
+  uint32_t            mRemovedCount;  // Removed entry sentinels in table.
+  EntryStore          mEntryStore;    // (Lazy) entry storage and generation.
+
+#ifdef DEBUG
+  mutable Checker mChecker;
+#endif
+
+public:
+  // Table capacity limit; do not exceed. The max capacity used to be 1<<23 but
+  // that occasionally that wasn't enough. Making it much bigger than 1<<26
+  // probably isn't worthwhile -- tables that big are kind of ridiculous.
+  // Also, the growth operation will (deliberately) fail if |capacity *
+  // mEntrySize| overflows a uint32_t, and mEntrySize is always at least 8
+  // bytes.
+  static const uint32_t kMaxCapacity = ((uint32_t)1 << 26);
+
+  static const uint32_t kMinCapacity = 8;
+
+  // Making this half of kMaxCapacity ensures it'll fit. Nobody should need an
+  // initial length anywhere nearly this large, anyway.
+  static const uint32_t kMaxInitialLength = kMaxCapacity / 2;
+
+  // This gives a default initial capacity of 8.
+  static const uint32_t kDefaultInitialLength = 4;
+
+  // Initialize the table with |aOps| and |aEntrySize|. The table's initial
+  // capacity is chosen such that |aLength| elements can be inserted without
+  // rehashing; if |aLength| is a power-of-two, this capacity will be
+  // |2*length|. However, because entry storage is allocated lazily, this
+  // initial capacity won't be relevant until the first element is added; prior
+  // to that the capacity will be zero.
+  //
+  // This will crash if |aEntrySize| and/or |aLength| are too large.
+  PLDHashTable(const PLDHashTableOps* aOps, uint32_t aEntrySize,
+               uint32_t aLength = kDefaultInitialLength);
+
+  PLDHashTable(PLDHashTable&& aOther)
+      // These two fields are |const|. Initialize them here because the
+      // move assignment operator cannot modify them.
+    : mOps(aOther.mOps)
+    , mEntrySize(aOther.mEntrySize)
+      // Initialize this field because it is required for a safe call to the
+      // destructor, which the move assignment operator does.
+    , mEntryStore()
+#ifdef DEBUG
+    , mChecker()
+#endif
+  {
+    *this = mozilla::Move(aOther);
+  }
+
+  PLDHashTable& operator=(PLDHashTable&& aOther);
+
+  ~PLDHashTable();
+
+  // This should be used rarely.
+  const PLDHashTableOps* Ops() const { return mOps; }
+
+  // Size in entries (gross, not net of free and removed sentinels) for table.
+  // This can be zero if no elements have been added yet, in which case the
+  // entry storage will not have yet been allocated.
+  uint32_t Capacity() const
+  {
+    return mEntryStore.Get() ? CapacityFromHashShift() : 0;
+  }
+
+  uint32_t EntrySize()  const { return mEntrySize; }
+  uint32_t EntryCount() const { return mEntryCount; }
+  uint32_t Generation() const { return mEntryStore.Generation(); }
+
+  // To search for a |key| in |table|, call:
+  //
+  //   entry = table.Search(key);
+  //
+  // If |entry| is non-null, |key| was found. If |entry| is null, key was not
+  // found.
+  PLDHashEntryHdr* Search(const void* aKey);
+
+  // To add an entry identified by |key| to table, call:
+  //
+  //   entry = table.Add(key, mozilla::fallible);
+  //
+  // If |entry| is null upon return, then the table is severely overloaded and
+  // memory can't be allocated for entry storage.
+  //
+  // Otherwise, |aEntry->mKeyHash| has been set so that
+  // PLDHashTable::EntryIsFree(entry) is false, and it is up to the caller to
+  // initialize the key and value parts of the entry sub-type, if they have not
+  // been set already (i.e. if entry was not already in the table, and if the
+  // optional initEntry hook was not used).
+  PLDHashEntryHdr* Add(const void* aKey, const mozilla::fallible_t&);
+
+  // This is like the other Add() function, but infallible, and so never
+  // returns null.
+  PLDHashEntryHdr* Add(const void* aKey);
+
+  // To remove an entry identified by |key| from table, call:
+  //
+  //   table.Remove(key);
+  //
+  // If |key|'s entry is found, it is cleared (via table->mOps->clearEntry).
+  // The table's capacity may be reduced afterwards.
+  void Remove(const void* aKey);
+
+  // To remove an entry found by a prior search, call:
+  //
+  //   table.RemoveEntry(entry);
+  //
+  // The entry, which must be present and in use, is cleared (via
+  // table->mOps->clearEntry). The table's capacity may be reduced afterwards.
+  void RemoveEntry(PLDHashEntryHdr* aEntry);
+
+  // Remove an entry already accessed via Search() or Add().
+  //
+  // NB: this is a "raw" or low-level method. It does not shrink the table if
+  // it is underloaded. Don't use it unless necessary and you know what you are
+  // doing, and if so, please explain in a comment why it is necessary instead
+  // of RemoveEntry().
+  void RawRemove(PLDHashEntryHdr* aEntry);
+
+  // This function is equivalent to
+  // ClearAndPrepareForLength(kDefaultInitialLength).
+  void Clear();
+
+  // This function clears the table's contents and frees its entry storage,
+  // leaving it in a empty state ready to be used again. Afterwards, when the
+  // first element is added the entry storage that gets allocated will have a
+  // capacity large enough to fit |aLength| elements without rehashing.
+  //
+  // It's conceptually the same as calling the destructor and then re-calling
+  // the constructor with the original |aOps| and |aEntrySize| arguments, and
+  // a new |aLength| argument.
+  void ClearAndPrepareForLength(uint32_t aLength);
+
+  // Measure the size of the table's entry storage. If the entries contain
+  // pointers to other heap blocks, you have to iterate over the table and
+  // measure those separately; hence the "Shallow" prefix.
+  size_t ShallowSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+  // Like ShallowSizeOfExcludingThis(), but includes sizeof(*this).
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+#ifdef DEBUG
+  // Mark a table as immutable for the remainder of its lifetime. This
+  // changes the implementation from asserting one set of invariants to
+  // asserting a different set.
+  void MarkImmutable();
+#endif
+
+  // If you use PLDHashEntryStub or a subclass of it as your entry struct, and
+  // if your entries move via memcpy and clear via memset(0), you can use these
+  // stub operations.
+  static const PLDHashTableOps* StubOps();
+
+  // The individual stub operations in StubOps().
+  static PLDHashNumber HashVoidPtrKeyStub(const void* aKey);
+  static bool MatchEntryStub(const PLDHashEntryHdr* aEntry, const void* aKey);
+  static void MoveEntryStub(PLDHashTable* aTable, const PLDHashEntryHdr* aFrom,
+                            PLDHashEntryHdr* aTo);
+  static void ClearEntryStub(PLDHashTable* aTable, PLDHashEntryHdr* aEntry);
+
+  // Hash/match operations for tables holding C strings.
+  static PLDHashNumber HashStringKey(const void* aKey);
+  static bool MatchStringKey(const PLDHashEntryHdr* aEntry, const void* aKey);
+
+  // This is an iterator for PLDHashtable. Assertions will detect some, but not
+  // all, mid-iteration table modifications that might invalidate (e.g.
+  // reallocate) the entry storage.
+  //
+  // Any element can be removed during iteration using Remove(). If any
+  // elements are removed, the table may be resized once iteration ends.
+  //
+  // Example usage:
+  //
+  //   for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {
+  //     auto entry = static_cast<FooEntry*>(iter.Get());
+  //     // ... do stuff with |entry| ...
+  //     // ... possibly call iter.Remove() once ...
+  //   }
+  //
+  // or:
+  //
+  //   for (PLDHashTable::Iterator iter(&table); !iter.Done(); iter.Next()) {
+  //     auto entry = static_cast<FooEntry*>(iter.Get());
+  //     // ... do stuff with |entry| ...
+  //     // ... possibly call iter.Remove() once ...
+  //   }
+  //
+  // The latter form is more verbose but is easier to work with when
+  // making subclasses of Iterator.
+  //
+  class Iterator
+  {
+  public:
+    explicit Iterator(PLDHashTable* aTable);
+    Iterator(Iterator&& aOther);
+    ~Iterator();
+
+    // Have we finished?
+    bool Done() const { return mNexts == mNextsLimit; }
+
+    // Get the current entry.
+    PLDHashEntryHdr* Get() const
+    {
+      MOZ_ASSERT(!Done());
+
+      PLDHashEntryHdr* entry = reinterpret_cast<PLDHashEntryHdr*>(mCurrent);
+      MOZ_ASSERT(EntryIsLive(entry));
+      return entry;
+    }
+
+    // Advance to the next entry.
+    void Next();
+
+    // Remove the current entry. Must only be called once per entry, and Get()
+    // must not be called on that entry afterwards.
+    void Remove();
+
+  protected:
+    PLDHashTable* mTable;             // Main table pointer.
+
+  private:
+    char* mStart;                     // The first entry.
+    char* mLimit;                     // One past the last entry.
+    char* mCurrent;                   // Pointer to the current entry.
+    uint32_t mNexts;                  // Number of Next() calls.
+    uint32_t mNextsLimit;             // Next() call limit.
+
+    bool mHaveRemoved;                // Have any elements been removed?
+
+    bool IsOnNonLiveEntry() const;
+    void MoveToNextEntry();
+
+    Iterator() = delete;
+    Iterator(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&&) = delete;
+  };
+
+  Iterator Iter() { return Iterator(this); }
+
+  // Use this if you need to initialize an Iterator in a const method. If you
+  // use this case, you should not call Remove() on the iterator.
+  Iterator ConstIter() const
+  {
+    return Iterator(const_cast<PLDHashTable*>(this));
+  }
+
+private:
+  // Multiplicative hash uses an unsigned 32 bit integer and the golden ratio,
+  // expressed as a fixed-point 32-bit fraction.
+  static const uint32_t kHashBits = 32;
+  static const uint32_t kGoldenRatio = 0x9E3779B9U;
+
+  static uint32_t HashShift(uint32_t aEntrySize, uint32_t aLength);
+
+  static const PLDHashNumber kCollisionFlag = 1;
+
+  static bool EntryIsFree(PLDHashEntryHdr* aEntry)
+  {
+    return aEntry->mKeyHash == 0;
+  }
+  static bool EntryIsRemoved(PLDHashEntryHdr* aEntry)
+  {
+    return aEntry->mKeyHash == 1;
+  }
+  static bool EntryIsLive(PLDHashEntryHdr* aEntry)
+  {
+    return aEntry->mKeyHash >= 2;
+  }
+
+  static void MarkEntryFree(PLDHashEntryHdr* aEntry)
+  {
+    aEntry->mKeyHash = 0;
+  }
+  static void MarkEntryRemoved(PLDHashEntryHdr* aEntry)
+  {
+    aEntry->mKeyHash = 1;
+  }
+
+  PLDHashNumber Hash1(PLDHashNumber aHash0);
+  void Hash2(PLDHashNumber aHash, uint32_t& aHash2Out, uint32_t& aSizeMaskOut);
+
+  static bool MatchEntryKeyhash(PLDHashEntryHdr* aEntry, PLDHashNumber aHash);
+  PLDHashEntryHdr* AddressEntry(uint32_t aIndex);
+
+  // We store mHashShift rather than sizeLog2 to optimize the collision-free
+  // case in SearchTable.
+  uint32_t CapacityFromHashShift() const
+  {
+    return ((uint32_t)1 << (kHashBits - mHashShift));
+  }
+
+  PLDHashNumber ComputeKeyHash(const void* aKey);
+
+  enum SearchReason { ForSearchOrRemove, ForAdd };
+
+  template <SearchReason Reason>
+  PLDHashEntryHdr* NS_FASTCALL
+    SearchTable(const void* aKey, PLDHashNumber aKeyHash);
+
+  PLDHashEntryHdr* FindFreeEntry(PLDHashNumber aKeyHash);
+
+  bool ChangeTable(int aDeltaLog2);
+
+  void ShrinkIfAppropriate();
+
+  PLDHashTable(const PLDHashTable& aOther) = delete;
+  PLDHashTable& operator=(const PLDHashTable& aOther) = delete;
+};
+
+// Compute the hash code for a given key to be looked up, added, or removed.
+// A hash code may have any PLDHashNumber value.
+typedef PLDHashNumber (*PLDHashHashKey)(const void* aKey);
+
+// Compare the key identifying aEntry with the provided key parameter. Return
+// true if keys match, false otherwise.
+typedef bool (*PLDHashMatchEntry)(const PLDHashEntryHdr* aEntry,
+                                  const void* aKey);
+
+// Copy the data starting at aFrom to the new entry storage at aTo. Do not add
+// reference counts for any strong references in the entry, however, as this
+// is a "move" operation: the old entry storage at from will be freed without
+// any reference-decrementing callback shortly.
+typedef void (*PLDHashMoveEntry)(PLDHashTable* aTable,
+                                 const PLDHashEntryHdr* aFrom,
+                                 PLDHashEntryHdr* aTo);
+
+// Clear the entry and drop any strong references it holds. This callback is
+// invoked by Remove(), but only if the given key is found in the table.
+typedef void (*PLDHashClearEntry)(PLDHashTable* aTable,
+                                  PLDHashEntryHdr* aEntry);
+
+// Initialize a new entry, apart from mKeyHash. This function is called when
+// Add() finds no existing entry for the given key, and must add a new one. At
+// that point, |aEntry->mKeyHash| is not set yet, to avoid claiming the last
+// free entry in a severely overloaded table.
+typedef void (*PLDHashInitEntry)(PLDHashEntryHdr* aEntry, const void* aKey);
+
+// Finally, the "vtable" structure for PLDHashTable. The first four hooks
+// must be provided by implementations; they're called unconditionally by the
+// generic PLDHashTable.cpp code. Hooks after these may be null.
+//
+// Summary of allocation-related hook usage with C++ placement new emphasis:
+//  initEntry           Call placement new using default key-based ctor.
+//  moveEntry           Call placement new using copy ctor, run dtor on old
+//                      entry storage.
+//  clearEntry          Run dtor on entry.
+//
+// Note the reason why initEntry is optional: the default hooks (stubs) clear
+// entry storage:  On successful Add(tbl, key), the returned entry pointer
+// addresses an entry struct whose mKeyHash member has been set non-zero, but
+// all other entry members are still clear (null). Add() callers can test such
+// members to see whether the entry was newly created by the Add() call that
+// just succeeded. If placement new or similar initialization is required,
+// define an |initEntry| hook. Of course, the |clearEntry| hook must zero or
+// null appropriately.
+//
+// XXX assumes 0 is null for pointer types.
+struct PLDHashTableOps
+{
+  // Mandatory hooks. All implementations must provide these.
+  PLDHashHashKey      hashKey;
+  PLDHashMatchEntry   matchEntry;
+  PLDHashMoveEntry    moveEntry;
+  PLDHashClearEntry   clearEntry;
+
+  // Optional hooks start here. If null, these are not called.
+  PLDHashInitEntry    initEntry;
+};
+
+// A minimal entry is a subclass of PLDHashEntryHdr and has a void* key pointer.
+struct PLDHashEntryStub : public PLDHashEntryHdr
+{
+  const void* key;
+};
+
+#endif /* PLDHashTable_h */
diff --git a/xpcom/glue/ReentrantMonitor.h b/xpcom/glue/ReentrantMonitor.h
new file mode 100644
index 0000000000..0798fe2af3
--- /dev/null
+++ b/xpcom/glue/ReentrantMonitor.h
@@ -0,0 +1,249 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ReentrantMonitor_h
+#define mozilla_ReentrantMonitor_h
+
+#include "prmon.h"
+
+#ifdef MOZILLA_INTERNAL_API
+#include "GeckoProfiler.h"
+#endif //MOZILLA_INTERNAL_API
+
+#include "mozilla/BlockingResourceBase.h"
+
+//
+// Provides:
+//
+//  - ReentrantMonitor, a Java-like monitor
+//  - ReentrantMonitorAutoEnter, an RAII class for ensuring that
+//    ReentrantMonitors are properly entered and exited
+//
+// Using ReentrantMonitorAutoEnter is MUCH preferred to making bare calls to
+// ReentrantMonitor.Enter and Exit.
+//
+namespace mozilla {
+
+
+/**
+ * ReentrantMonitor
+ * Java-like monitor.
+ * When possible, use ReentrantMonitorAutoEnter to hold this monitor within a
+ * scope, instead of calling Enter/Exit directly.
+ **/
+class ReentrantMonitor : BlockingResourceBase
+{
+public:
+  /**
+   * ReentrantMonitor
+   * @param aName A name which can reference this monitor
+   */
+  explicit ReentrantMonitor(const char* aName)
+    : BlockingResourceBase(aName, eReentrantMonitor)
+#ifdef DEBUG
+    , mEntryCount(0)
+#endif
+  {
+    MOZ_COUNT_CTOR(ReentrantMonitor);
+    mReentrantMonitor = PR_NewMonitor();
+    if (!mReentrantMonitor) {
+      NS_RUNTIMEABORT("Can't allocate mozilla::ReentrantMonitor");
+    }
+  }
+
+  /**
+   * ~ReentrantMonitor
+   **/
+  ~ReentrantMonitor()
+  {
+    NS_ASSERTION(mReentrantMonitor,
+                 "improperly constructed ReentrantMonitor or double free");
+    PR_DestroyMonitor(mReentrantMonitor);
+    mReentrantMonitor = 0;
+    MOZ_COUNT_DTOR(ReentrantMonitor);
+  }
+
+#ifndef DEBUG
+  /**
+   * Enter
+   * @see prmon.h
+   **/
+  void Enter() { PR_EnterMonitor(mReentrantMonitor); }
+
+  /**
+   * Exit
+   * @see prmon.h
+   **/
+  void Exit() { PR_ExitMonitor(mReentrantMonitor); }
+
+  /**
+   * Wait
+   * @see prmon.h
+   **/
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT)
+  {
+#ifdef MOZILLA_INTERNAL_API
+    GeckoProfilerSleepRAII profiler_sleep;
+#endif //MOZILLA_INTERNAL_API
+    return PR_Wait(mReentrantMonitor, aInterval) == PR_SUCCESS ?
+      NS_OK : NS_ERROR_FAILURE;
+  }
+
+#else // ifndef DEBUG
+  void Enter();
+  void Exit();
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT);
+
+#endif  // ifndef DEBUG
+
+  /**
+   * Notify
+   * @see prmon.h
+   **/
+  nsresult Notify()
+  {
+    return PR_Notify(mReentrantMonitor) == PR_SUCCESS ? NS_OK :
+                                                        NS_ERROR_FAILURE;
+  }
+
+  /**
+   * NotifyAll
+   * @see prmon.h
+   **/
+  nsresult NotifyAll()
+  {
+    return PR_NotifyAll(mReentrantMonitor) == PR_SUCCESS ? NS_OK :
+                                                           NS_ERROR_FAILURE;
+  }
+
+#ifdef DEBUG
+  /**
+   * AssertCurrentThreadIn
+   * @see prmon.h
+   **/
+  void AssertCurrentThreadIn()
+  {
+    PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mReentrantMonitor);
+  }
+
+  /**
+   * AssertNotCurrentThreadIn
+   * @see prmon.h
+   **/
+  void AssertNotCurrentThreadIn()
+  {
+    // FIXME bug 476536
+  }
+
+#else
+  void AssertCurrentThreadIn() {}
+  void AssertNotCurrentThreadIn() {}
+
+#endif  // ifdef DEBUG
+
+private:
+  ReentrantMonitor();
+  ReentrantMonitor(const ReentrantMonitor&);
+  ReentrantMonitor& operator=(const ReentrantMonitor&);
+
+  PRMonitor* mReentrantMonitor;
+#ifdef DEBUG
+  int32_t mEntryCount;
+#endif
+};
+
+
+/**
+ * ReentrantMonitorAutoEnter
+ * Enters the ReentrantMonitor when it enters scope, and exits it when
+ * it leaves scope.
+ *
+ * MUCH PREFERRED to bare calls to ReentrantMonitor.Enter and Exit.
+ */
+class MOZ_STACK_CLASS ReentrantMonitorAutoEnter
+{
+public:
+  /**
+   * Constructor
+   * The constructor aquires the given lock.  The destructor
+   * releases the lock.
+   *
+   * @param aReentrantMonitor A valid mozilla::ReentrantMonitor*.
+   **/
+  explicit ReentrantMonitorAutoEnter(mozilla::ReentrantMonitor& aReentrantMonitor)
+    : mReentrantMonitor(&aReentrantMonitor)
+  {
+    NS_ASSERTION(mReentrantMonitor, "null monitor");
+    mReentrantMonitor->Enter();
+  }
+
+  ~ReentrantMonitorAutoEnter(void)
+  {
+    mReentrantMonitor->Exit();
+  }
+
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT)
+  {
+    return mReentrantMonitor->Wait(aInterval);
+  }
+
+  nsresult Notify() { return mReentrantMonitor->Notify(); }
+  nsresult NotifyAll() { return mReentrantMonitor->NotifyAll(); }
+
+private:
+  ReentrantMonitorAutoEnter();
+  ReentrantMonitorAutoEnter(const ReentrantMonitorAutoEnter&);
+  ReentrantMonitorAutoEnter& operator=(const ReentrantMonitorAutoEnter&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  mozilla::ReentrantMonitor* mReentrantMonitor;
+};
+
+/**
+ * ReentrantMonitorAutoExit
+ * Exit the ReentrantMonitor when it enters scope, and enters it when it leaves
+ * scope.
+ *
+ * MUCH PREFERRED to bare calls to ReentrantMonitor.Exit and Enter.
+ */
+class MOZ_STACK_CLASS ReentrantMonitorAutoExit
+{
+public:
+  /**
+   * Constructor
+   * The constructor releases the given lock.  The destructor
+   * acquires the lock. The lock must be held before constructing
+   * this object!
+   *
+   * @param aReentrantMonitor A valid mozilla::ReentrantMonitor*. It
+   *                 must be already locked.
+   **/
+  explicit ReentrantMonitorAutoExit(ReentrantMonitor& aReentrantMonitor)
+    : mReentrantMonitor(&aReentrantMonitor)
+  {
+    NS_ASSERTION(mReentrantMonitor, "null monitor");
+    mReentrantMonitor->AssertCurrentThreadIn();
+    mReentrantMonitor->Exit();
+  }
+
+  ~ReentrantMonitorAutoExit(void)
+  {
+    mReentrantMonitor->Enter();
+  }
+
+private:
+  ReentrantMonitorAutoExit();
+  ReentrantMonitorAutoExit(const ReentrantMonitorAutoExit&);
+  ReentrantMonitorAutoExit& operator=(const ReentrantMonitorAutoExit&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  ReentrantMonitor* mReentrantMonitor;
+};
+
+} // namespace mozilla
+
+
+#endif // ifndef mozilla_ReentrantMonitor_h
diff --git a/xpcom/glue/moz.build b/xpcom/glue/moz.build
new file mode 100644
index 0000000000..95c18b273e
--- /dev/null
+++ b/xpcom/glue/moz.build
@@ -0,0 +1,123 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+with Files('nsString*'):
+    BUG_COMPONENT = ('Core', 'String')
+
+DIRS += ['standalone']
+
+# On win we build two glue libs - glue linked to crt dlls here and in staticruntime we build
+# a statically linked glue lib.
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DIRS += ['staticruntime']
+
+EXPORTS += [
+    'MainThreadUtils.h',
+    'nsArrayEnumerator.h',
+    'nsArrayUtils.h',
+    'nsBaseHashtable.h',
+    'nsCategoryCache.h',
+    'nsClassHashtable.h',
+    'nsCOMArray.h',
+    'nsComponentManagerUtils.h',
+    'nsCOMPtr.h',
+    'nsCRTGlue.h',
+    'nsCycleCollectionNoteChild.h',
+    'nsCycleCollectionNoteRootCallback.h',
+    'nsCycleCollectionParticipant.h',
+    'nsCycleCollectionTraversalCallback.h',
+    'nsDataHashtable.h',
+    'nsDebug.h',
+    'nsDeque.h',
+    'nsEnumeratorUtils.h',
+    'nsHashKeys.h',
+    'nsIClassInfoImpl.h',
+    'nsID.h',
+    'nsIInterfaceRequestorUtils.h',
+    'nsINIParser.h',
+    'nsInterfaceHashtable.h',
+    'nsISupportsImpl.h',
+    'nsISupportsUtils.h',
+    'nsIWeakReferenceUtils.h',
+    'nsJSThingHashtable.h',
+    'nsMemory.h',
+    'nsPointerHashKeys.h',
+    'nsProxyRelease.h',
+    'nsQuickSort.h',
+    'nsRefPtrHashtable.h',
+    'nsServiceManagerUtils.h',
+    'nsStringAPI.h',
+    'nsStringGlue.h',
+    'nsTArray-inl.h',
+    'nsTArray.h',
+    'nsTArrayForwardDeclare.h',
+    'nsTextFormatter.h',
+    'nsTHashtable.h',
+    'nsThreadUtils.h',
+    'nsTObserverArray.h',
+    'nsTPriorityQueue.h',
+    'nsTWeakRef.h',
+    'nsVersionComparator.h',
+    'nsWeakReference.h',
+    'nsXPTCUtils.h',
+    'PLDHashTable.h',
+]
+
+EXPORTS.mozilla += [
+    'AppData.h',
+    'AutoRestore.h',
+    'BlockingResourceBase.h',
+    'CondVar.h',
+    'DeadlockDetector.h',
+    'EnumeratedArrayCycleCollection.h',
+    'FileUtils.h',
+    'GenericFactory.h',
+    'IntentionalCrash.h',
+    'Monitor.h',
+    'Mutex.h',
+    'Observer.h',
+    'ReentrantMonitor.h',
+]
+
+include('objs.mozbuild')
+
+UNIFIED_SOURCES += xpcom_gluens_src_cppsrcs
+UNIFIED_SOURCES += xpcom_glue_src_cppsrcs
+
+UNIFIED_SOURCES += [
+    'GenericModule.cpp',
+    'nsStringAPI.cpp',
+]
+
+Library('xpcomglue_s')
+
+SDK_LIBRARY = True
+
+FORCE_STATIC_LIB = True
+
+if CONFIG['_MSC_VER']:
+    DEFINES['_USE_ANSI_CPP'] = True
+    # Don't include directives about which CRT to use
+    CFLAGS += ['-Zl']
+    CXXFLAGS += ['-Zl']
+
+LOCAL_INCLUDES += [
+    '../build',
+    '../threads',
+]
+
+if CONFIG['ENABLE_TESTS']:
+    DIRS += ['tests/gtest']
+
+# Include fallible for third party code using the xpcom glue
+USE_LIBS += [
+    'fallible',
+]
+
+# Force to build a static library only
+NO_EXPAND_LIBS = True
+
+DIST_INSTALL = True
diff --git a/xpcom/glue/nsArrayEnumerator.cpp b/xpcom/glue/nsArrayEnumerator.cpp
new file mode 100644
index 0000000000..2d2ef6da78
--- /dev/null
+++ b/xpcom/glue/nsArrayEnumerator.cpp
@@ -0,0 +1,213 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Attributes.h"
+
+#include "nsArrayEnumerator.h"
+
+#include "nsIArray.h"
+#include "nsISimpleEnumerator.h"
+
+#include "nsCOMArray.h"
+#include "nsCOMPtr.h"
+#include "mozilla/RefPtr.h"
+
+class nsSimpleArrayEnumerator final : public nsISimpleEnumerator
+{
+public:
+  // nsISupports interface
+  NS_DECL_ISUPPORTS
+
+  // nsISimpleEnumerator interface
+  NS_DECL_NSISIMPLEENUMERATOR
+
+  // nsSimpleArrayEnumerator methods
+  explicit nsSimpleArrayEnumerator(nsIArray* aValueArray)
+    : mValueArray(aValueArray)
+    , mIndex(0)
+  {
+  }
+
+private:
+  ~nsSimpleArrayEnumerator() {}
+
+protected:
+  nsCOMPtr<nsIArray> mValueArray;
+  uint32_t mIndex;
+};
+
+NS_IMPL_ISUPPORTS(nsSimpleArrayEnumerator, nsISimpleEnumerator)
+
+NS_IMETHODIMP
+nsSimpleArrayEnumerator::HasMoreElements(bool* aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (!mValueArray) {
+    *aResult = false;
+    return NS_OK;
+  }
+
+  uint32_t cnt;
+  nsresult rv = mValueArray->GetLength(&cnt);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  *aResult = (mIndex < cnt);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSimpleArrayEnumerator::GetNext(nsISupports** aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (!mValueArray) {
+    *aResult = nullptr;
+    return NS_OK;
+  }
+
+  uint32_t cnt;
+  nsresult rv = mValueArray->GetLength(&cnt);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (mIndex >= cnt) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  return mValueArray->QueryElementAt(mIndex++, NS_GET_IID(nsISupports),
+                                     (void**)aResult);
+}
+
+nsresult
+NS_NewArrayEnumerator(nsISimpleEnumerator** aResult, nsIArray* aArray)
+{
+  RefPtr<nsSimpleArrayEnumerator> enumer = new nsSimpleArrayEnumerator(aArray);
+  enumer.forget(aResult);
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+// enumerator implementation for nsCOMArray
+// creates a snapshot of the array in question
+// you MUST use NS_NewArrayEnumerator to create this, so that
+// allocation is done correctly
+class nsCOMArrayEnumerator final : public nsISimpleEnumerator
+{
+public:
+  // nsISupports interface
+  NS_DECL_ISUPPORTS
+
+  // nsISimpleEnumerator interface
+  NS_DECL_NSISIMPLEENUMERATOR
+
+  // nsSimpleArrayEnumerator methods
+  nsCOMArrayEnumerator() : mIndex(0) {}
+
+  // specialized operator to make sure we make room for mValues
+  void* operator new(size_t aSize, const nsCOMArray_base& aArray) CPP_THROW_NEW;
+  void operator delete(void* aPtr) { ::operator delete(aPtr); }
+
+private:
+  ~nsCOMArrayEnumerator(void);
+
+protected:
+  uint32_t mIndex;            // current position
+  uint32_t mArraySize;        // size of the array
+
+  // this is actually bigger
+  nsISupports* mValueArray[1];
+};
+
+NS_IMPL_ISUPPORTS(nsCOMArrayEnumerator, nsISimpleEnumerator)
+
+nsCOMArrayEnumerator::~nsCOMArrayEnumerator()
+{
+  // only release the entries that we haven't visited yet
+  for (; mIndex < mArraySize; ++mIndex) {
+    NS_IF_RELEASE(mValueArray[mIndex]);
+  }
+}
+
+NS_IMETHODIMP
+nsCOMArrayEnumerator::HasMoreElements(bool* aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  *aResult = (mIndex < mArraySize);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsCOMArrayEnumerator::GetNext(nsISupports** aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (mIndex >= mArraySize) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // pass the ownership of the reference to the caller. Since
+  // we AddRef'ed during creation of |this|, there is no need
+  // to AddRef here
+  *aResult = mValueArray[mIndex++];
+
+  // this really isn't necessary. just pretend this happens, since
+  // we'll never visit this value again!
+  // mValueArray[(mIndex-1)] = nullptr;
+
+  return NS_OK;
+}
+
+void*
+nsCOMArrayEnumerator::operator new(size_t aSize,
+                                   const nsCOMArray_base& aArray) CPP_THROW_NEW
+{
+  // create enough space such that mValueArray points to a large
+  // enough value. Note that the initial value of aSize gives us
+  // space for mValueArray[0], so we must subtract
+  aSize += (aArray.Count() - 1) * sizeof(aArray[0]);
+
+  // do the actual allocation
+  nsCOMArrayEnumerator* result =
+    static_cast<nsCOMArrayEnumerator*>(::operator new(aSize));
+
+  // now need to copy over the values, and addref each one
+  // now this might seem like a lot of work, but we're actually just
+  // doing all our AddRef's ahead of time since GetNext() doesn't
+  // need to AddRef() on the way out
+  uint32_t i;
+  uint32_t max = result->mArraySize = aArray.Count();
+  for (i = 0; i < max; ++i) {
+    result->mValueArray[i] = aArray[i];
+    NS_IF_ADDREF(result->mValueArray[i]);
+  }
+
+  return result;
+}
+
+nsresult
+NS_NewArrayEnumerator(nsISimpleEnumerator** aResult,
+                      const nsCOMArray_base& aArray)
+{
+  RefPtr<nsCOMArrayEnumerator> enumerator = new (aArray) nsCOMArrayEnumerator();
+  enumerator.forget(aResult);
+  return NS_OK;
+}
diff --git a/xpcom/glue/nsArrayEnumerator.h b/xpcom/glue/nsArrayEnumerator.h
new file mode 100644
index 0000000000..341ae86eda
--- /dev/null
+++ b/xpcom/glue/nsArrayEnumerator.h
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsArrayEnumerator_h__
+#define nsArrayEnumerator_h__
+
+// enumerator implementation for nsIArray
+
+#include "nscore.h"
+
+class nsISimpleEnumerator;
+class nsIArray;
+class nsCOMArray_base;
+
+// Create an enumerator for an existing nsIArray implementation
+// The enumerator holds an owning reference to the array.
+nsresult
+NS_NewArrayEnumerator(nsISimpleEnumerator** aResult,
+                      nsIArray* aArray);
+
+// create an enumerator for an existing nsCOMArray<T> implementation
+// The enumerator will hold an owning reference to each ELEMENT in
+// the array. This means that the nsCOMArray<T> can safely go away
+// without its objects going away.
+nsresult
+NS_NewArrayEnumerator(nsISimpleEnumerator** aResult,
+                      const nsCOMArray_base& aArray);
+
+#endif
diff --git a/xpcom/glue/nsArrayUtils.cpp b/xpcom/glue/nsArrayUtils.cpp
new file mode 100644
index 0000000000..4808637376
--- /dev/null
+++ b/xpcom/glue/nsArrayUtils.cpp
@@ -0,0 +1,23 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsArrayUtils.h"
+
+//
+// do_QueryElementAt helper stuff
+//
+nsresult
+nsQueryArrayElementAt::operator()(const nsIID& aIID, void** aResult) const
+{
+  nsresult status = mArray ? mArray->QueryElementAt(mIndex, aIID, aResult) :
+                             NS_ERROR_NULL_POINTER;
+
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+
+  return status;
+}
diff --git a/xpcom/glue/nsArrayUtils.h b/xpcom/glue/nsArrayUtils.h
new file mode 100644
index 0000000000..68032e8c0a
--- /dev/null
+++ b/xpcom/glue/nsArrayUtils.h
@@ -0,0 +1,40 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsArrayUtils_h__
+#define nsArrayUtils_h__
+
+#include "nsCOMPtr.h"
+#include "nsIArray.h"
+
+// helper class for do_QueryElementAt
+class MOZ_STACK_CLASS nsQueryArrayElementAt final : public nsCOMPtr_helper
+{
+public:
+  nsQueryArrayElementAt(nsIArray* aArray, uint32_t aIndex,
+                        nsresult* aErrorPtr)
+    : mArray(aArray)
+    , mIndex(aIndex)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const
+    override;
+
+private:
+  nsIArray* MOZ_NON_OWNING_REF mArray;
+  uint32_t   mIndex;
+  nsresult*  mErrorPtr;
+};
+
+inline const nsQueryArrayElementAt
+do_QueryElementAt(nsIArray* aArray, uint32_t aIndex, nsresult* aErrorPtr = 0)
+{
+  return nsQueryArrayElementAt(aArray, aIndex, aErrorPtr);
+}
+
+#endif // nsArrayUtils_h__
diff --git a/xpcom/glue/nsBaseHashtable.h b/xpcom/glue/nsBaseHashtable.h
new file mode 100644
index 0000000000..f52df3dd18
--- /dev/null
+++ b/xpcom/glue/nsBaseHashtable.h
@@ -0,0 +1,270 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsBaseHashtable_h__
+#define nsBaseHashtable_h__
+
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Move.h"
+#include "nsTHashtable.h"
+#include "nsDebug.h"
+
+template<class KeyClass, class DataType, class UserDataType>
+class nsBaseHashtable; // forward declaration
+
+/**
+ * the private nsTHashtable::EntryType class used by nsBaseHashtable
+ * @see nsTHashtable for the specification of this class
+ * @see nsBaseHashtable for template parameters
+ */
+template<class KeyClass, class DataType>
+class nsBaseHashtableET : public KeyClass
+{
+public:
+  DataType mData;
+  friend class nsTHashtable<nsBaseHashtableET<KeyClass, DataType>>;
+
+private:
+  typedef typename KeyClass::KeyType KeyType;
+  typedef typename KeyClass::KeyTypePointer KeyTypePointer;
+
+  explicit nsBaseHashtableET(KeyTypePointer aKey);
+  nsBaseHashtableET(nsBaseHashtableET<KeyClass, DataType>&& aToMove);
+  ~nsBaseHashtableET();
+};
+
+/**
+ * templated hashtable for simple data types
+ * This class manages simple data types that do not need construction or
+ * destruction.
+ *
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param DataType the datatype stored in the hashtable,
+ *   for example, uint32_t or nsCOMPtr.  If UserDataType is not the same,
+ *   DataType must implicitly cast to UserDataType
+ * @param UserDataType the user sees, for example uint32_t or nsISupports*
+ */
+template<class KeyClass, class DataType, class UserDataType>
+class nsBaseHashtable
+  : protected nsTHashtable<nsBaseHashtableET<KeyClass, DataType>>
+{
+  typedef mozilla::fallible_t fallible_t;
+
+public:
+  typedef typename KeyClass::KeyType KeyType;
+  typedef nsBaseHashtableET<KeyClass, DataType> EntryType;
+
+  using nsTHashtable<EntryType>::Contains;
+
+  nsBaseHashtable() {}
+  explicit nsBaseHashtable(uint32_t aInitLength)
+    : nsTHashtable<EntryType>(aInitLength)
+  {
+  }
+
+  /**
+   * Return the number of entries in the table.
+   * @return    number of entries
+   */
+  uint32_t Count() const { return nsTHashtable<EntryType>::Count(); }
+
+  /**
+   * retrieve the value for a key.
+   * @param aKey the key to retreive
+   * @param aData data associated with this key will be placed at this
+   *   pointer.  If you only need to check if the key exists, aData
+   *   may be null.
+   * @return true if the key exists. If key does not exist, aData is not
+   *   modified.
+   */
+  bool Get(KeyType aKey, UserDataType* aData) const
+  {
+    EntryType* ent = this->GetEntry(aKey);
+    if (!ent) {
+      return false;
+    }
+
+    if (aData) {
+      *aData = ent->mData;
+    }
+
+    return true;
+  }
+
+  /**
+   * Get the value, returning a zero-initialized POD or a default-initialized
+   * object if the entry is not present in the table.
+   *
+   * @param aKey the key to retrieve
+   * @return The found value, or UserDataType{} if no entry was found with the
+   *         given key.
+   * @note If zero/default-initialized values are stored in the table, it is
+   *       not possible to distinguish between such a value and a missing entry.
+   */
+  UserDataType Get(KeyType aKey) const
+  {
+    EntryType* ent = this->GetEntry(aKey);
+    if (!ent) {
+      return UserDataType{};
+    }
+
+    return ent->mData;
+  }
+
+  /**
+   * Add key to the table if not already present, and return a reference to its
+   * value.  If key is not already in the table then the value is default
+   * constructed.
+   */
+  DataType& GetOrInsert(const KeyType& aKey)
+  {
+    EntryType* ent = this->GetEntry(aKey);
+    if (ent) {
+      return ent->mData;
+    }
+
+    ent = this->PutEntry(aKey);
+    return ent->mData;
+  }
+
+  /**
+   * put a new value for the associated key
+   * @param aKey the key to put
+   * @param aData the new data
+   * @return always true, unless memory allocation failed
+   */
+  void Put(KeyType aKey, const UserDataType& aData)
+  {
+    if (!Put(aKey, aData, mozilla::fallible)) {
+      NS_ABORT_OOM(this->mTable.EntrySize() * this->mTable.EntryCount());
+    }
+  }
+
+  MOZ_MUST_USE bool Put(KeyType aKey, const UserDataType& aData,
+                        const fallible_t&)
+  {
+    EntryType* ent = this->PutEntry(aKey, mozilla::fallible);
+    if (!ent) {
+      return false;
+    }
+
+    ent->mData = aData;
+
+    return true;
+  }
+
+  /**
+   * remove the data for the associated key
+   * @param aKey the key to remove from the hashtable
+   */
+  void Remove(KeyType aKey) { this->RemoveEntry(aKey); }
+
+  // This is an iterator that also allows entry removal. Example usage:
+  //
+  //   for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {
+  //     const KeyType key = iter.Key();
+  //     const UserDataType data = iter.UserData();
+  //     // or
+  //     const DataType& data = iter.Data();
+  //     // ... do stuff with |key| and/or |data| ...
+  //     // ... possibly call iter.Remove() once ...
+  //   }
+  //
+  class Iterator : public PLDHashTable::Iterator
+  {
+  public:
+    typedef PLDHashTable::Iterator Base;
+
+    explicit Iterator(nsBaseHashtable* aTable) : Base(&aTable->mTable) {}
+    Iterator(Iterator&& aOther) : Base(aOther.mTable) {}
+    ~Iterator() {}
+
+    KeyType Key() const { return static_cast<EntryType*>(Get())->GetKey(); }
+    UserDataType UserData() const
+    {
+      return static_cast<EntryType*>(Get())->mData;
+    }
+    DataType& Data() const { return static_cast<EntryType*>(Get())->mData; }
+
+  private:
+    Iterator() = delete;
+    Iterator(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&&) = delete;
+  };
+
+  Iterator Iter() { return Iterator(this); }
+
+  Iterator ConstIter() const
+  {
+    return Iterator(const_cast<nsBaseHashtable*>(this));
+  }
+
+  /**
+   * reset the hashtable, removing all entries
+   */
+  void Clear() { nsTHashtable<EntryType>::Clear(); }
+
+  /**
+   * Measure the size of the table's entry storage. The size of things pointed
+   * to by entries must be measured separately; hence the "Shallow" prefix.
+   *
+   * @param   aMallocSizeOf the function used to measure heap-allocated blocks
+   * @return  the summed size of the table's storage
+   */
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return this->mTable.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * Like ShallowSizeOfExcludingThis, but includes sizeof(*this).
+   */
+  size_t ShallowSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * Swap the elements in this hashtable with the elements in aOther.
+   */
+  void SwapElements(nsBaseHashtable& aOther)
+  {
+    nsTHashtable<EntryType>::SwapElements(aOther);
+  }
+
+
+#ifdef DEBUG
+  using nsTHashtable<EntryType>::MarkImmutable;
+#endif
+};
+
+//
+// nsBaseHashtableET definitions
+//
+
+template<class KeyClass, class DataType>
+nsBaseHashtableET<KeyClass, DataType>::nsBaseHashtableET(KeyTypePointer aKey)
+  : KeyClass(aKey)
+  , mData()
+{
+}
+
+template<class KeyClass, class DataType>
+nsBaseHashtableET<KeyClass, DataType>::nsBaseHashtableET(
+      nsBaseHashtableET<KeyClass, DataType>&& aToMove)
+  : KeyClass(mozilla::Move(aToMove))
+  , mData(mozilla::Move(aToMove.mData))
+{
+}
+
+template<class KeyClass, class DataType>
+nsBaseHashtableET<KeyClass, DataType>::~nsBaseHashtableET()
+{
+}
+
+#endif // nsBaseHashtable_h__
diff --git a/xpcom/glue/nsCOMArray.cpp b/xpcom/glue/nsCOMArray.cpp
new file mode 100644
index 0000000000..3522f7b0d1
--- /dev/null
+++ b/xpcom/glue/nsCOMArray.cpp
@@ -0,0 +1,323 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCOMArray.h"
+
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/OperatorNewExtensions.h"
+
+#include "nsCOMPtr.h"
+
+// This specialization is private to nsCOMArray.
+// It exists solely to automatically zero-out newly created array elements.
+template<>
+class nsTArrayElementTraits<nsISupports*>
+{
+  typedef nsISupports* E;
+public:
+  // Zero out the value
+  static inline void Construct(E* aE)
+  {
+    new (mozilla::KnownNotNull, static_cast<void*>(aE)) E();
+  }
+  // Invoke the copy-constructor in place.
+  template<class A>
+  static inline void Construct(E* aE, const A& aArg)
+  {
+    new (mozilla::KnownNotNull, static_cast<void*>(aE)) E(aArg);
+  }
+  // Invoke the destructor in place.
+  static inline void Destruct(E* aE)
+  {
+    aE->~E();
+  }
+};
+
+static void ReleaseObjects(nsTArray<nsISupports*>& aArray);
+
+// implementations of non-trivial methods in nsCOMArray_base
+
+nsCOMArray_base::nsCOMArray_base(const nsCOMArray_base& aOther)
+{
+  // make sure we do only one allocation
+  mArray.SetCapacity(aOther.Count());
+  AppendObjects(aOther);
+}
+
+nsCOMArray_base::~nsCOMArray_base()
+{
+  Clear();
+}
+
+int32_t
+nsCOMArray_base::IndexOf(nsISupports* aObject, uint32_t aStartIndex) const
+{
+  return mArray.IndexOf(aObject, aStartIndex);
+}
+
+int32_t
+nsCOMArray_base::IndexOfObject(nsISupports* aObject) const
+{
+  nsCOMPtr<nsISupports> supports = do_QueryInterface(aObject);
+  if (NS_WARN_IF(!supports)) {
+    return -1;
+  }
+
+  uint32_t i, count;
+  int32_t retval = -1;
+  count = mArray.Length();
+  for (i = 0; i < count; ++i) {
+    nsCOMPtr<nsISupports> arrayItem = do_QueryInterface(mArray[i]);
+    if (arrayItem == supports) {
+      retval = i;
+      break;
+    }
+  }
+  return retval;
+}
+
+bool
+nsCOMArray_base::EnumerateForwards(nsBaseArrayEnumFunc aFunc, void* aData) const
+{
+  for (uint32_t index = 0; index < mArray.Length(); ++index) {
+    if (!(*aFunc)(mArray[index], aData)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool
+nsCOMArray_base::EnumerateBackwards(nsBaseArrayEnumFunc aFunc, void* aData) const
+{
+  for (uint32_t index = mArray.Length(); index--; ) {
+    if (!(*aFunc)(mArray[index], aData)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+int
+nsCOMArray_base::nsCOMArrayComparator(const void* aElement1,
+                                      const void* aElement2,
+                                      void* aData)
+{
+  nsCOMArrayComparatorContext* ctx =
+    static_cast<nsCOMArrayComparatorContext*>(aData);
+  return (*ctx->mComparatorFunc)(*static_cast<nsISupports* const*>(aElement1),
+                                 *static_cast<nsISupports* const*>(aElement2),
+                                 ctx->mData);
+}
+
+void
+nsCOMArray_base::Sort(nsBaseArrayComparatorFunc aFunc, void* aData)
+{
+  if (mArray.Length() > 1) {
+    nsCOMArrayComparatorContext ctx = {aFunc, aData};
+    NS_QuickSort(mArray.Elements(), mArray.Length(), sizeof(nsISupports*),
+                 nsCOMArrayComparator, &ctx);
+  }
+}
+
+bool
+nsCOMArray_base::InsertObjectAt(nsISupports* aObject, int32_t aIndex)
+{
+  if ((uint32_t)aIndex > mArray.Length()) {
+    return false;
+  }
+
+  if (!mArray.InsertElementAt(aIndex, aObject)) {
+    return false;
+  }
+
+  NS_IF_ADDREF(aObject);
+  return true;
+}
+
+void
+nsCOMArray_base::InsertElementAt(uint32_t aIndex, nsISupports* aElement)
+{
+  mArray.InsertElementAt(aIndex, aElement);
+  NS_IF_ADDREF(aElement);
+}
+
+void
+nsCOMArray_base::InsertElementAt(uint32_t aIndex, already_AddRefed<nsISupports> aElement)
+{
+  mArray.InsertElementAt(aIndex, aElement.take());
+}
+
+bool
+nsCOMArray_base::InsertObjectsAt(const nsCOMArray_base& aObjects, int32_t aIndex)
+{
+  if ((uint32_t)aIndex > mArray.Length()) {
+    return false;
+  }
+
+  if (!mArray.InsertElementsAt(aIndex, aObjects.mArray)) {
+    return false;
+  }
+
+  // need to addref all these
+  uint32_t count = aObjects.Length();
+  for (uint32_t i = 0; i < count; ++i) {
+    NS_IF_ADDREF(aObjects[i]);
+  }
+
+  return true;
+}
+
+void
+nsCOMArray_base::InsertElementsAt(uint32_t aIndex,
+                                  const nsCOMArray_base& aElements)
+{
+  mArray.InsertElementsAt(aIndex, aElements.mArray);
+
+  // need to addref all these
+  uint32_t count = aElements.Length();
+  for (uint32_t i = 0; i < count; ++i) {
+    NS_IF_ADDREF(aElements[i]);
+  }
+}
+
+void
+nsCOMArray_base::InsertElementsAt(uint32_t aIndex,
+                                  nsISupports* const* aElements,
+                                  uint32_t aCount)
+{
+  mArray.InsertElementsAt(aIndex, aElements, aCount);
+
+  // need to addref all these
+  for (uint32_t i = 0; i < aCount; ++i) {
+    NS_IF_ADDREF(aElements[i]);
+  }
+}
+
+void
+nsCOMArray_base::ReplaceObjectAt(nsISupports* aObject, int32_t aIndex)
+{
+  mArray.EnsureLengthAtLeast(aIndex + 1);
+  nsISupports* oldObject = mArray[aIndex];
+  // Make sure to addref first, in case aObject == oldObject
+  NS_IF_ADDREF(mArray[aIndex] = aObject);
+  NS_IF_RELEASE(oldObject);
+}
+
+bool
+nsCOMArray_base::RemoveObject(nsISupports* aObject)
+{
+  bool result = mArray.RemoveElement(aObject);
+  if (result) {
+    NS_IF_RELEASE(aObject);
+  }
+  return result;
+}
+
+bool
+nsCOMArray_base::RemoveObjectAt(int32_t aIndex)
+{
+  if (uint32_t(aIndex) < mArray.Length()) {
+    nsISupports* element = mArray[aIndex];
+
+    mArray.RemoveElementAt(aIndex);
+    NS_IF_RELEASE(element);
+    return true;
+  }
+
+  return false;
+}
+
+void
+nsCOMArray_base::RemoveElementAt(uint32_t aIndex)
+{
+  nsISupports* element = mArray[aIndex];
+  mArray.RemoveElementAt(aIndex);
+  NS_IF_RELEASE(element);
+}
+
+bool
+nsCOMArray_base::RemoveObjectsAt(int32_t aIndex, int32_t aCount)
+{
+  if (uint32_t(aIndex) + uint32_t(aCount) <= mArray.Length()) {
+    nsTArray<nsISupports*> elementsToDestroy(aCount);
+    elementsToDestroy.AppendElements(mArray.Elements() + aIndex, aCount);
+    mArray.RemoveElementsAt(aIndex, aCount);
+    ReleaseObjects(elementsToDestroy);
+    return true;
+  }
+
+  return false;
+}
+
+void
+nsCOMArray_base::RemoveElementsAt(uint32_t aIndex, uint32_t aCount)
+{
+  nsTArray<nsISupports*> elementsToDestroy(aCount);
+  elementsToDestroy.AppendElements(mArray.Elements() + aIndex, aCount);
+  mArray.RemoveElementsAt(aIndex, aCount);
+  ReleaseObjects(elementsToDestroy);
+}
+
+// useful for destructors
+void
+ReleaseObjects(nsTArray<nsISupports*>& aArray)
+{
+  for (uint32_t i = 0; i < aArray.Length(); ++i) {
+    NS_IF_RELEASE(aArray[i]);
+  }
+}
+
+void
+nsCOMArray_base::Clear()
+{
+  nsTArray<nsISupports*> objects;
+  objects.SwapElements(mArray);
+  ReleaseObjects(objects);
+}
+
+bool
+nsCOMArray_base::SetCount(int32_t aNewCount)
+{
+  NS_ASSERTION(aNewCount >= 0, "SetCount(negative index)");
+  if (aNewCount < 0) {
+    return false;
+  }
+
+  int32_t count = mArray.Length();
+  if (count > aNewCount) {
+    RemoveObjectsAt(aNewCount, mArray.Length() - aNewCount);
+  }
+  mArray.SetLength(aNewCount);
+  return true;
+}
+
+void
+nsCOMArray_base::Adopt(nsISupports** aElements, uint32_t aSize)
+{
+  Clear();
+  mArray.AppendElements(aElements, aSize);
+
+  // Free the allocated array as well.
+  NS_Free(aElements);
+}
+
+uint32_t
+nsCOMArray_base::Forget(nsISupports*** aElements)
+{
+  uint32_t length = Length();
+  size_t array_size = sizeof(nsISupports*) * length;
+  nsISupports** array = static_cast<nsISupports**>(NS_Alloc(array_size));
+  memmove(array, Elements(), array_size);
+  *aElements = array;
+  // Don't Release the contained pointers; the caller of the method will
+  // do this eventually.
+  mArray.Clear();
+
+  return length;
+}
diff --git a/xpcom/glue/nsCOMArray.h b/xpcom/glue/nsCOMArray.h
new file mode 100644
index 0000000000..56d077a2fd
--- /dev/null
+++ b/xpcom/glue/nsCOMArray.h
@@ -0,0 +1,473 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCOMArray_h__
+#define nsCOMArray_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/MemoryReporting.h"
+
+#include "nsCycleCollectionNoteChild.h"
+#include "nsTArray.h"
+#include "nsISupports.h"
+
+// See below for the definition of nsCOMArray<T>
+
+// a class that's nsISupports-specific, so that we can contain the
+// work of this class in the XPCOM dll
+class nsCOMArray_base
+{
+  friend class nsArrayBase;
+protected:
+  nsCOMArray_base() {}
+  explicit nsCOMArray_base(int32_t aCount) : mArray(aCount) {}
+  nsCOMArray_base(const nsCOMArray_base& aOther);
+  ~nsCOMArray_base();
+
+  int32_t IndexOf(nsISupports* aObject, uint32_t aStartIndex = 0) const;
+  bool Contains(nsISupports* aObject) const
+  {
+    return IndexOf(aObject) != -1;
+  }
+
+  int32_t IndexOfObject(nsISupports* aObject) const;
+  bool ContainsObject(nsISupports* aObject) const
+  {
+    return IndexOfObject(aObject) != -1;
+  }
+
+  typedef bool (*nsBaseArrayEnumFunc)(void* aElement, void* aData);
+
+  // enumerate through the array with a callback.
+  bool EnumerateForwards(nsBaseArrayEnumFunc aFunc, void* aData) const;
+
+  bool EnumerateBackwards(nsBaseArrayEnumFunc aFunc, void* aData) const;
+
+  typedef int (*nsBaseArrayComparatorFunc)(nsISupports* aElement1,
+                                           nsISupports* aElement2,
+                                           void* aData);
+
+  struct nsCOMArrayComparatorContext
+  {
+    nsBaseArrayComparatorFunc mComparatorFunc;
+    void* mData;
+  };
+
+  static int nsCOMArrayComparator(const void* aElement1, const void* aElement2,
+                                  void* aData);
+  void Sort(nsBaseArrayComparatorFunc aFunc, void* aData);
+
+  bool InsertObjectAt(nsISupports* aObject, int32_t aIndex);
+  void InsertElementAt(uint32_t aIndex, nsISupports* aElement);
+  void InsertElementAt(uint32_t aIndex, already_AddRefed<nsISupports> aElement);
+  bool InsertObjectsAt(const nsCOMArray_base& aObjects, int32_t aIndex);
+  void InsertElementsAt(uint32_t aIndex, const nsCOMArray_base& aElements);
+  void InsertElementsAt(uint32_t aIndex, nsISupports* const* aElements,
+                        uint32_t aCount);
+  void ReplaceObjectAt(nsISupports* aObject, int32_t aIndex);
+  void ReplaceElementAt(uint32_t aIndex, nsISupports* aElement)
+  {
+    nsISupports* oldElement = mArray[aIndex];
+    NS_IF_ADDREF(mArray[aIndex] = aElement);
+    NS_IF_RELEASE(oldElement);
+  }
+  bool AppendObject(nsISupports* aObject)
+  {
+    return InsertObjectAt(aObject, Count());
+  }
+  void AppendElement(nsISupports* aElement)
+  {
+    InsertElementAt(Length(), aElement);
+  }
+  void AppendElement(already_AddRefed<nsISupports> aElement)
+  {
+    InsertElementAt(Length(), mozilla::Move(aElement));
+  }
+
+  bool AppendObjects(const nsCOMArray_base& aObjects)
+  {
+    return InsertObjectsAt(aObjects, Count());
+  }
+  void AppendElements(const nsCOMArray_base& aElements)
+  {
+    return InsertElementsAt(Length(), aElements);
+  }
+  void AppendElements(nsISupports* const* aElements, uint32_t aCount)
+  {
+    return InsertElementsAt(Length(), aElements, aCount);
+  }
+  bool RemoveObject(nsISupports* aObject);
+  nsISupports** Elements() { return mArray.Elements(); }
+  void SwapElements(nsCOMArray_base& aOther)
+  {
+    mArray.SwapElements(aOther.mArray);
+  }
+
+  void Adopt(nsISupports** aElements, uint32_t aCount);
+  uint32_t Forget(nsISupports*** aElements);
+public:
+  // elements in the array (including null elements!)
+  int32_t Count() const { return mArray.Length(); }
+  // nsTArray-compatible version
+  uint32_t Length() const { return mArray.Length(); }
+  bool IsEmpty() const { return mArray.IsEmpty(); }
+
+  // If the array grows, the newly created entries will all be null;
+  // if the array shrinks, the excess entries will all be released.
+  bool SetCount(int32_t aNewCount);
+  // nsTArray-compatible version
+  void TruncateLength(uint32_t aNewLength)
+  {
+    if (mArray.Length() > aNewLength) {
+      RemoveElementsAt(aNewLength, mArray.Length() - aNewLength);
+    }
+  }
+
+  // remove all elements in the array, and call NS_RELEASE on each one
+  void Clear();
+
+  nsISupports* ObjectAt(int32_t aIndex) const { return mArray[aIndex]; }
+  // nsTArray-compatible version
+  nsISupports* ElementAt(uint32_t aIndex) const { return mArray[aIndex]; }
+
+  nsISupports* SafeObjectAt(int32_t aIndex) const
+  {
+    return mArray.SafeElementAt(aIndex, nullptr);
+  }
+  // nsTArray-compatible version
+  nsISupports* SafeElementAt(uint32_t aIndex) const
+  {
+    return mArray.SafeElementAt(aIndex, nullptr);
+  }
+
+  nsISupports* operator[](int32_t aIndex) const { return mArray[aIndex]; }
+
+  // remove an element at a specific position, shrinking the array
+  // as necessary
+  bool RemoveObjectAt(int32_t aIndex);
+  // nsTArray-compatible version
+  void RemoveElementAt(uint32_t aIndex);
+
+  // remove a range of elements at a specific position, shrinking the array
+  // as necessary
+  bool RemoveObjectsAt(int32_t aIndex, int32_t aCount);
+  // nsTArray-compatible version
+  void RemoveElementsAt(uint32_t aIndex, uint32_t aCount);
+
+  void SwapElementsAt(uint32_t aIndex1, uint32_t aIndex2)
+  {
+    nsISupports* tmp = mArray[aIndex1];
+    mArray[aIndex1] = mArray[aIndex2];
+    mArray[aIndex2] = tmp;
+  }
+
+  // Ensures there is enough space to store a total of aCapacity objects.
+  // This method never deletes any objects.
+  void SetCapacity(uint32_t aCapacity) { mArray.SetCapacity(aCapacity); }
+  uint32_t Capacity() { return mArray.Capacity(); }
+
+  // Measures the size of the array's element storage. If you want to measure
+  // anything hanging off the array, you must iterate over the elements and
+  // measure them individually; hence the "Shallow" prefix. Note that because
+  // each element in an nsCOMArray<T> is actually a T* any such iteration
+  // should use a SizeOfIncludingThis() function on each element rather than a
+  // SizeOfExcludingThis() function, so that the memory taken by the T itself
+  // is included as well as anything it points to.
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return mArray.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+private:
+
+  // the actual storage
+  nsTArray<nsISupports*> mArray;
+
+  // don't implement these, defaults will muck with refcounts!
+  nsCOMArray_base& operator=(const nsCOMArray_base& aOther) = delete;
+};
+
+inline void
+ImplCycleCollectionUnlink(nsCOMArray_base& aField)
+{
+  aField.Clear();
+}
+
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsCOMArray_base& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  aFlags |= CycleCollectionEdgeNameArrayFlag;
+  int32_t length = aField.Count();
+  for (int32_t i = 0; i < length; ++i) {
+    CycleCollectionNoteChild(aCallback, aField[i], aName, aFlags);
+  }
+}
+
+
+// a non-XPCOM, refcounting array of XPCOM objects
+// used as a member variable or stack variable - this object is NOT
+// refcounted, but the objects that it holds are
+//
+// most of the read-only accessors like ObjectAt()/etc do NOT refcount
+// on the way out. This means that you can do one of two things:
+//
+// * does an addref, but holds onto a reference
+// nsCOMPtr<T> foo = array[i];
+//
+// * avoids the refcount, but foo might go stale if array[i] is ever
+// * modified/removed. Be careful not to NS_RELEASE(foo)!
+// T* foo = array[i];
+//
+// This array will accept null as an argument for any object, and will store
+// null in the array. But that also means that methods like ObjectAt() may
+// return null when referring to an existing, but null entry in the array.
+template<class T>
+class nsCOMArray : public nsCOMArray_base
+{
+public:
+  nsCOMArray() {}
+  explicit nsCOMArray(int32_t aCount) : nsCOMArray_base(aCount) {}
+  explicit nsCOMArray(const nsCOMArray<T>& aOther) : nsCOMArray_base(aOther) {}
+  nsCOMArray(nsCOMArray<T>&& aOther) { SwapElements(aOther); }
+  ~nsCOMArray() {}
+
+  // We have a move assignment operator, but no copy assignment operator.
+  nsCOMArray<T>& operator=(nsCOMArray<T> && aOther)
+  {
+    SwapElements(aOther);
+    return *this;
+  }
+
+  // these do NOT refcount on the way out, for speed
+  T* ObjectAt(int32_t aIndex) const
+  {
+    return static_cast<T*>(nsCOMArray_base::ObjectAt(aIndex));
+  }
+  // nsTArray-compatible version
+  T* ElementAt(uint32_t aIndex) const
+  {
+    return static_cast<T*>(nsCOMArray_base::ElementAt(aIndex));
+  }
+
+  // these do NOT refcount on the way out, for speed
+  T* SafeObjectAt(int32_t aIndex) const
+  {
+    return static_cast<T*>(nsCOMArray_base::SafeObjectAt(aIndex));
+  }
+  // nsTArray-compatible version
+  T* SafeElementAt(uint32_t aIndex) const
+  {
+    return static_cast<T*>(nsCOMArray_base::SafeElementAt(aIndex));
+  }
+
+  // indexing operator for syntactic sugar
+  T* operator[](int32_t aIndex) const { return ObjectAt(aIndex); }
+
+  // index of the element in question.. does NOT refcount
+  // note: this does not check COM object identity. Use
+  // IndexOfObject() for that purpose
+  int32_t IndexOf(T* aObject, uint32_t aStartIndex = 0) const
+  {
+    return nsCOMArray_base::IndexOf(aObject, aStartIndex);
+  }
+  bool Contains(T* aObject) const
+  {
+    return nsCOMArray_base::Contains(aObject);
+  }
+
+  // index of the element in question.. be careful!
+  // this is much slower than IndexOf() because it uses
+  // QueryInterface to determine actual COM identity of the object
+  // if you need to do this frequently then consider enforcing
+  // COM object identity before adding/comparing elements
+  int32_t IndexOfObject(T* aObject) const
+  {
+    return nsCOMArray_base::IndexOfObject(aObject);
+  }
+  bool ContainsObject(nsISupports* aObject) const
+  {
+    return nsCOMArray_base::ContainsObject(aObject);
+  }
+
+  // inserts aObject at aIndex, shifting the objects at aIndex and
+  // later to make space
+  bool InsertObjectAt(T* aObject, int32_t aIndex)
+  {
+    return nsCOMArray_base::InsertObjectAt(aObject, aIndex);
+  }
+  // nsTArray-compatible version
+  void InsertElementAt(uint32_t aIndex, T* aElement)
+  {
+    nsCOMArray_base::InsertElementAt(aIndex, aElement);
+  }
+
+  // inserts the objects from aObject at aIndex, shifting the
+  // objects at aIndex and later to make space
+  bool InsertObjectsAt(const nsCOMArray<T>& aObjects, int32_t aIndex)
+  {
+    return nsCOMArray_base::InsertObjectsAt(aObjects, aIndex);
+  }
+  // nsTArray-compatible version
+  void InsertElementsAt(uint32_t aIndex, const nsCOMArray<T>& aElements)
+  {
+    nsCOMArray_base::InsertElementsAt(aIndex, aElements);
+  }
+  void InsertElementsAt(uint32_t aIndex, T* const* aElements, uint32_t aCount)
+  {
+    nsCOMArray_base::InsertElementsAt(
+      aIndex, reinterpret_cast<nsISupports* const*>(aElements), aCount);
+  }
+
+  // replaces an existing element. Warning: if the array grows,
+  // the newly created entries will all be null
+  void ReplaceObjectAt(T* aObject, int32_t aIndex)
+  {
+    nsCOMArray_base::ReplaceObjectAt(aObject, aIndex);
+  }
+  // nsTArray-compatible version
+  void ReplaceElementAt(uint32_t aIndex, T* aElement)
+  {
+    nsCOMArray_base::ReplaceElementAt(aIndex, aElement);
+  }
+
+  // Enumerator callback function. Return false to stop
+  // Here's a more readable form:
+  // bool enumerate(T* aElement, void* aData)
+  typedef bool (*nsCOMArrayEnumFunc)(T* aElement, void* aData);
+
+  // enumerate through the array with a callback.
+  bool EnumerateForwards(nsCOMArrayEnumFunc aFunc, void* aData)
+  {
+    return nsCOMArray_base::EnumerateForwards(nsBaseArrayEnumFunc(aFunc),
+                                              aData);
+  }
+
+  bool EnumerateBackwards(nsCOMArrayEnumFunc aFunc, void* aData)
+  {
+    return nsCOMArray_base::EnumerateBackwards(nsBaseArrayEnumFunc(aFunc),
+                                               aData);
+  }
+
+  typedef int (*nsCOMArrayComparatorFunc)(T* aElement1, T* aElement2,
+                                          void* aData);
+
+  void Sort(nsCOMArrayComparatorFunc aFunc, void* aData)
+  {
+    nsCOMArray_base::Sort(nsBaseArrayComparatorFunc(aFunc), aData);
+  }
+
+  // append an object, growing the array as necessary
+  bool AppendObject(T* aObject)
+  {
+    return nsCOMArray_base::AppendObject(aObject);
+  }
+  // nsTArray-compatible version
+  void AppendElement(T* aElement)
+  {
+    nsCOMArray_base::AppendElement(aElement);
+  }
+  void AppendElement(already_AddRefed<T> aElement)
+  {
+    nsCOMArray_base::AppendElement(mozilla::Move(aElement));
+  }
+
+  // append objects, growing the array as necessary
+  bool AppendObjects(const nsCOMArray<T>& aObjects)
+  {
+    return nsCOMArray_base::AppendObjects(aObjects);
+  }
+  // nsTArray-compatible version
+  void AppendElements(const nsCOMArray<T>& aElements)
+  {
+    return nsCOMArray_base::AppendElements(aElements);
+  }
+  void AppendElements(T* const* aElements, uint32_t aCount)
+  {
+    InsertElementsAt(Length(), aElements, aCount);
+  }
+
+  // remove the first instance of the given object and shrink the
+  // array as necessary
+  // Warning: if you pass null here, it will remove the first null element
+  bool RemoveObject(T* aObject)
+  {
+    return nsCOMArray_base::RemoveObject(aObject);
+  }
+  // nsTArray-compatible version
+  bool RemoveElement(T* aElement)
+  {
+    return nsCOMArray_base::RemoveObject(aElement);
+  }
+
+  T** Elements()
+  {
+    return reinterpret_cast<T**>(nsCOMArray_base::Elements());
+  }
+  void SwapElements(nsCOMArray<T>& aOther)
+  {
+    nsCOMArray_base::SwapElements(aOther);
+  }
+
+  /**
+   * Adopt parameters that resulted from an XPIDL outparam. The aElements
+   * parameter will be freed as a result of the call.
+   *
+   * Example usage:
+   * nsCOMArray<nsISomeInterface> array;
+   * nsISomeInterface** elements;
+   * uint32_t length;
+   * ptr->GetSomeArray(&elements, &length);
+   * array.Adopt(elements, length);
+   */
+  void Adopt(T** aElements, uint32_t aSize)
+  {
+    nsCOMArray_base::Adopt(reinterpret_cast<nsISupports**>(aElements), aSize);
+  }
+
+  /**
+   * Export the contents of this array to an XPIDL outparam. The array will be
+   * Clear()'d after this operation.
+   *
+   * Example usage:
+   * nsCOMArray<nsISomeInterface> array;
+   * *length = array.Forget(retval);
+   */
+  uint32_t Forget(T*** aElements)
+  {
+    return nsCOMArray_base::Forget(reinterpret_cast<nsISupports***>(aElements));
+  }
+
+private:
+
+  // don't implement these!
+  nsCOMArray<T>& operator=(const nsCOMArray<T>& aOther) = delete;
+};
+
+template<typename T>
+inline void
+ImplCycleCollectionUnlink(nsCOMArray<T>& aField)
+{
+  aField.Clear();
+}
+
+template<typename E>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsCOMArray<E>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  aFlags |= CycleCollectionEdgeNameArrayFlag;
+  int32_t length = aField.Count();
+  for (int32_t i = 0; i < length; ++i) {
+    CycleCollectionNoteChild(aCallback, aField[i], aName, aFlags);
+  }
+}
+
+#endif
diff --git a/xpcom/glue/nsCOMPtr.cpp b/xpcom/glue/nsCOMPtr.cpp
new file mode 100644
index 0000000000..263fa62c2d
--- /dev/null
+++ b/xpcom/glue/nsCOMPtr.cpp
@@ -0,0 +1,128 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCOMPtr.h"
+
+nsresult
+nsQueryInterface::operator()(const nsIID& aIID, void** aAnswer) const
+{
+  nsresult status;
+  if (mRawPtr) {
+    status = mRawPtr->QueryInterface(aIID, aAnswer);
+  } else {
+    status = NS_ERROR_NULL_POINTER;
+  }
+
+  return status;
+}
+
+nsresult
+nsQueryInterfaceWithError::operator()(const nsIID& aIID, void** aAnswer) const
+{
+  nsresult status;
+  if (mRawPtr) {
+    status = mRawPtr->QueryInterface(aIID, aAnswer);
+  } else {
+    status = NS_ERROR_NULL_POINTER;
+  }
+
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+void
+nsCOMPtr_base::assign_with_AddRef(nsISupports* aRawPtr)
+{
+  if (aRawPtr) {
+    NSCAP_ADDREF(this, aRawPtr);
+  }
+  assign_assuming_AddRef(aRawPtr);
+}
+
+void
+nsCOMPtr_base::assign_from_qi(const nsQueryInterface aQI, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aQI(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_qi_with_error(const nsQueryInterfaceWithError& aQI,
+                                         const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aQI(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_gs_cid(const nsGetServiceByCID aGS,
+                                  const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_gs_cid_with_error(
+    const nsGetServiceByCIDWithError& aGS, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_gs_contractid(const nsGetServiceByContractID aGS,
+                                         const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_gs_contractid_with_error(
+    const nsGetServiceByContractIDWithError& aGS, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_helper(const nsCOMPtr_helper& aHelper,
+                                  const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aHelper(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void**
+nsCOMPtr_base::begin_assignment()
+{
+  assign_assuming_AddRef(nullptr);
+  return reinterpret_cast<void**>(&mRawPtr);
+}
diff --git a/xpcom/glue/nsCOMPtr.h b/xpcom/glue/nsCOMPtr.h
new file mode 100644
index 0000000000..373f55cbb9
--- /dev/null
+++ b/xpcom/glue/nsCOMPtr.h
@@ -0,0 +1,1472 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCOMPtr_h___
+#define nsCOMPtr_h___
+
+/*
+ * Having problems?
+ *
+ * See the User Manual at:
+ *   http://www.mozilla.org/projects/xpcom/nsCOMPtr.html
+ *
+ *
+ * nsCOMPtr
+ *   better than a raw pointer
+ * for owning objects
+ *                      -- scc
+ */
+
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Move.h"
+#include "mozilla/TypeTraits.h"
+
+#include "nsDebug.h" // for |NS_ASSERTION|
+#include "nsISupportsUtils.h" // for |nsresult|, |NS_ADDREF|, |NS_GET_TEMPLATE_IID| et al
+#include "mozilla/RefPtr.h"
+
+#include "nsCycleCollectionNoteChild.h"
+
+
+/*
+ * WARNING: This file defines several macros for internal use only. These
+ * macros begin with the prefix |NSCAP_|. Do not use these macros in your own
+ * code. They are for internal use only for cross-platform compatibility, and
+ * are subject to change without notice.
+ */
+
+
+#ifdef _MSC_VER
+  // Under VC++, we win by inlining StartAssignment.
+  #define NSCAP_FEATURE_INLINE_STARTASSIGNMENT
+
+  // Also under VC++, at the highest warning level, we are overwhelmed with
+  // warnings about (unused) inline functions being removed. This is to be
+  // expected with templates, so we disable the warning.
+  #pragma warning( disable: 4514 )
+#endif
+
+#define NSCAP_FEATURE_USE_BASE
+
+#ifdef DEBUG
+  #define NSCAP_FEATURE_TEST_DONTQUERY_CASES
+  #undef NSCAP_FEATURE_USE_BASE
+#endif
+
+#ifdef __GNUC__
+  // Our use of nsCOMPtr_base::mRawPtr violates the C++ standard's aliasing
+  // rules. Mark it with the may_alias attribute so that gcc 3.3 and higher
+  // don't reorder instructions based on aliasing assumptions for
+  // this variable.  Fortunately, gcc versions < 3.3 do not do any
+  // optimizations that break nsCOMPtr.
+
+  #define NS_MAY_ALIAS_PTR(t)    t*  __attribute__((__may_alias__))
+#else
+  #define NS_MAY_ALIAS_PTR(t)    t*
+#endif
+
+#if defined(NSCAP_DISABLE_DEBUG_PTR_TYPES)
+  #define NSCAP_FEATURE_USE_BASE
+#endif
+
+/*
+ * The following three macros (NSCAP_ADDREF, NSCAP_RELEASE, and
+ * NSCAP_LOG_ASSIGNMENT) allow external clients the ability to add logging or
+ * other interesting debug facilities. In fact, if you want |nsCOMPtr| to
+ * participate in the standard logging facility, you provide
+ * (e.g., in "nsISupportsImpl.h") suitable definitions
+ *
+ *   #define NSCAP_ADDREF(this, ptr)         NS_ADDREF(ptr)
+ *   #define NSCAP_RELEASE(this, ptr)        NS_RELEASE(ptr)
+ */
+
+#ifndef NSCAP_ADDREF
+  #define NSCAP_ADDREF(this, ptr)     (ptr)->AddRef()
+#endif
+
+#ifndef NSCAP_RELEASE
+  #define NSCAP_RELEASE(this, ptr)    (ptr)->Release()
+#endif
+
+// Clients can define |NSCAP_LOG_ASSIGNMENT| to perform logging.
+#ifdef NSCAP_LOG_ASSIGNMENT
+  // Remember that |NSCAP_LOG_ASSIGNMENT| was defined by some client so that we
+  // know to instantiate |~nsGetterAddRefs| in turn to note the external
+  // assignment into the |nsCOMPtr|.
+  #define NSCAP_LOG_EXTERNAL_ASSIGNMENT
+#else
+    // ...otherwise, just strip it out of the code
+  #define NSCAP_LOG_ASSIGNMENT(this, ptr)
+#endif
+
+#ifndef NSCAP_LOG_RELEASE
+  #define NSCAP_LOG_RELEASE(this, ptr)
+#endif
+
+namespace mozilla {
+template<class T> class OwningNonNull;
+} // namespace mozilla
+
+template<class T>
+inline already_AddRefed<T>
+dont_AddRef(T* aRawPtr)
+{
+  return already_AddRefed<T>(aRawPtr);
+}
+
+template<class T>
+inline already_AddRefed<T>&&
+dont_AddRef(already_AddRefed<T>&& aAlreadyAddRefedPtr)
+{
+  return mozilla::Move(aAlreadyAddRefedPtr);
+}
+
+
+/*
+ * An nsCOMPtr_helper transforms commonly called getters into typesafe forms
+ * that are more convenient to call, and more efficient to use with |nsCOMPtr|s.
+ * Good candidates for helpers are |QueryInterface()|, |CreateInstance()|, etc.
+ *
+ * Here are the rules for a helper:
+ *   - it implements |operator()| to produce an interface pointer
+ *   - (except for its name) |operator()| is a valid [XP]COM `getter'
+ *   - the interface pointer that it returns is already |AddRef()|ed (as from
+ *     any good getter)
+ *   - it matches the type requested with the supplied |nsIID| argument
+ *   - its constructor provides an optional |nsresult*| that |operator()| can
+ *     fill in with an error when it is executed
+ *
+ * See |class nsGetInterface| for an example.
+ */
+class MOZ_STACK_CLASS nsCOMPtr_helper
+{
+public:
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const = 0;
+};
+
+/*
+ * nsQueryInterface could have been implemented as an nsCOMPtr_helper to avoid
+ * adding specialized machinery in nsCOMPtr, but do_QueryInterface is called
+ * often enough that the codesize savings are big enough to warrant the
+ * specialcasing.
+ */
+class MOZ_STACK_CLASS nsQueryInterface final
+{
+public:
+  explicit
+  nsQueryInterface(nsISupports* aRawPtr) : mRawPtr(aRawPtr) {}
+
+  nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const;
+
+private:
+  nsISupports* MOZ_OWNING_REF mRawPtr;
+};
+
+class nsQueryInterfaceWithError final
+{
+public:
+  nsQueryInterfaceWithError(nsISupports* aRawPtr, nsresult* aError)
+    : mRawPtr(aRawPtr)
+    , mErrorPtr(aError)
+  {
+  }
+
+  nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const;
+
+private:
+  nsISupports* MOZ_OWNING_REF mRawPtr;
+  nsresult* mErrorPtr;
+};
+
+inline nsQueryInterface
+do_QueryInterface(nsISupports* aRawPtr)
+{
+  return nsQueryInterface(aRawPtr);
+}
+
+inline nsQueryInterfaceWithError
+do_QueryInterface(nsISupports* aRawPtr, nsresult* aError)
+{
+  return nsQueryInterfaceWithError(aRawPtr, aError);
+}
+
+template<class T>
+inline void
+do_QueryInterface(already_AddRefed<T>&)
+{
+  // This signature exists solely to _stop_ you from doing the bad thing.
+  // Saying |do_QueryInterface()| on a pointer that is not otherwise owned by
+  // someone else is an automatic leak. See bug 8221.
+}
+
+template<class T>
+inline void
+do_QueryInterface(already_AddRefed<T>&, nsresult*)
+{
+  // This signature exists solely to _stop_ you from doing the bad thing.
+  // Saying |do_QueryInterface()| on a pointer that is not otherwise owned by
+  // someone else is an automatic leak. See bug 8221.
+}
+
+
+////////////////////////////////////////////////////////////////////////////
+// Using servicemanager with COMPtrs
+class nsGetServiceByCID final
+{
+public:
+  explicit nsGetServiceByCID(const nsCID& aCID) : mCID(aCID) {}
+
+  nsresult NS_FASTCALL operator()(const nsIID&, void**) const;
+
+private:
+  const nsCID& mCID;
+};
+
+class nsGetServiceByCIDWithError final
+{
+public:
+  nsGetServiceByCIDWithError(const nsCID& aCID, nsresult* aErrorPtr)
+    : mCID(aCID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  nsresult NS_FASTCALL operator()(const nsIID&, void**) const;
+
+private:
+  const nsCID& mCID;
+  nsresult* mErrorPtr;
+};
+
+class nsGetServiceByContractID final
+{
+public:
+  explicit nsGetServiceByContractID(const char* aContractID)
+    : mContractID(aContractID)
+  {
+  }
+
+  nsresult NS_FASTCALL operator()(const nsIID&, void**) const;
+
+private:
+  const char* mContractID;
+};
+
+class nsGetServiceByContractIDWithError final
+{
+public:
+  nsGetServiceByContractIDWithError(const char* aContractID, nsresult* aErrorPtr)
+    : mContractID(aContractID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  nsresult NS_FASTCALL operator()(const nsIID&, void**) const;
+
+private:
+  const char* mContractID;
+  nsresult* mErrorPtr;
+};
+
+/**
+ * Factors implementation for all template versions of nsCOMPtr.
+ *
+ * Here's the way people normally do things like this:
+ *
+ *   template<class T> class Foo { ... };
+ *   template<> class Foo<void*> { ... };
+ *   template<class T> class Foo<T*> : private Foo<void*> { ... };
+ */
+class nsCOMPtr_base
+{
+public:
+  explicit nsCOMPtr_base(nsISupports* aRawPtr = nullptr) : mRawPtr(aRawPtr) {}
+
+  NS_CONSTRUCTOR_FASTCALL ~nsCOMPtr_base()
+  {
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    if (mRawPtr) {
+      NSCAP_RELEASE(this, mRawPtr);
+    }
+  }
+
+  void NS_FASTCALL
+  assign_with_AddRef(nsISupports*);
+  void NS_FASTCALL
+  assign_from_qi(const nsQueryInterface, const nsIID&);
+  void NS_FASTCALL
+  assign_from_qi_with_error(const nsQueryInterfaceWithError&, const nsIID&);
+  void NS_FASTCALL
+  assign_from_gs_cid(const nsGetServiceByCID, const nsIID&);
+  void NS_FASTCALL
+  assign_from_gs_cid_with_error(const nsGetServiceByCIDWithError&, const nsIID&);
+  void NS_FASTCALL
+  assign_from_gs_contractid(const nsGetServiceByContractID, const nsIID&);
+  void NS_FASTCALL
+  assign_from_gs_contractid_with_error(const nsGetServiceByContractIDWithError&,
+                                       const nsIID&);
+  void NS_FASTCALL
+  assign_from_helper(const nsCOMPtr_helper&, const nsIID&);
+  void** NS_FASTCALL
+  begin_assignment();
+
+protected:
+  NS_MAY_ALIAS_PTR(nsISupports) MOZ_OWNING_REF mRawPtr;
+
+  void assign_assuming_AddRef(nsISupports* aNewPtr)
+  {
+    // |AddRef()|ing the new value (before entering this function) before
+    // |Release()|ing the old lets us safely ignore the self-assignment case.
+    // We must, however, be careful only to |Release()| _after_ doing the
+    // assignment, in case the |Release()| leads to our _own_ destruction,
+    // which would, in turn, cause an incorrect second |Release()| of our old
+    // pointer. Thank <waterson@netscape.com> for discovering this.
+    nsISupports* oldPtr = mRawPtr;
+    mRawPtr = aNewPtr;
+    NSCAP_LOG_ASSIGNMENT(this, aNewPtr);
+    NSCAP_LOG_RELEASE(this, oldPtr);
+    if (oldPtr) {
+      NSCAP_RELEASE(this, oldPtr);
+    }
+  }
+};
+
+// template<class T> class nsGetterAddRefs;
+
+// Helper for assert_validity method
+template<class T>
+char (&TestForIID(decltype(&NS_GET_TEMPLATE_IID(T))))[2];
+template<class T>
+char TestForIID(...);
+
+template<class T>
+class nsCOMPtr final
+#ifdef NSCAP_FEATURE_USE_BASE
+  : private nsCOMPtr_base
+#endif
+{
+
+#ifdef NSCAP_FEATURE_USE_BASE
+  #define NSCAP_CTOR_BASE(x) nsCOMPtr_base(x)
+#else
+  #define NSCAP_CTOR_BASE(x) mRawPtr(x)
+
+private:
+  void assign_with_AddRef(nsISupports*);
+  void assign_from_qi(const nsQueryInterface, const nsIID&);
+  void assign_from_qi_with_error(const nsQueryInterfaceWithError&, const nsIID&);
+  void assign_from_gs_cid(const nsGetServiceByCID, const nsIID&);
+  void assign_from_gs_cid_with_error(const nsGetServiceByCIDWithError&,
+                                     const nsIID&);
+  void assign_from_gs_contractid(const nsGetServiceByContractID, const nsIID&);
+  void assign_from_gs_contractid_with_error(
+    const nsGetServiceByContractIDWithError&, const nsIID&);
+  void assign_from_helper(const nsCOMPtr_helper&, const nsIID&);
+  void** begin_assignment();
+
+  void assign_assuming_AddRef(T* aNewPtr)
+  {
+    T* oldPtr = mRawPtr;
+    mRawPtr = aNewPtr;
+    NSCAP_LOG_ASSIGNMENT(this, aNewPtr);
+    NSCAP_LOG_RELEASE(this, oldPtr);
+    if (oldPtr) {
+      NSCAP_RELEASE(this, oldPtr);
+    }
+  }
+
+private:
+  T* MOZ_OWNING_REF mRawPtr;
+#endif
+
+  void assert_validity()
+  {
+    static_assert(1 < sizeof(TestForIID<T>(nullptr)), "nsCOMPtr only works "
+                  "for types with IIDs.  Either use RefPtr; add an IID to "
+                  "your type with NS_DECLARE_STATIC_IID_ACCESSOR/"
+                  "NS_DEFINE_STATIC_IID_ACCESSOR; or make the nsCOMPtr point "
+                  "to a base class with an IID.");
+  }
+
+public:
+  typedef T element_type;
+
+#ifndef NSCAP_FEATURE_USE_BASE
+  ~nsCOMPtr()
+  {
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    if (mRawPtr) {
+      NSCAP_RELEASE(this, mRawPtr);
+    }
+  }
+#endif
+
+#ifdef NSCAP_FEATURE_TEST_DONTQUERY_CASES
+  void Assert_NoQueryNeeded()
+  {
+    if (mRawPtr) {
+      nsCOMPtr<T> query_result(do_QueryInterface(mRawPtr));
+      NS_ASSERTION(query_result.get() == mRawPtr, "QueryInterface needed");
+    }
+  }
+
+  #define NSCAP_ASSERT_NO_QUERY_NEEDED() Assert_NoQueryNeeded();
+#else
+  #define NSCAP_ASSERT_NO_QUERY_NEEDED()
+#endif
+
+
+  // Constructors
+
+  nsCOMPtr()
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+  }
+
+  MOZ_IMPLICIT nsCOMPtr(decltype(nullptr))
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+  }
+
+  nsCOMPtr(const nsCOMPtr<T>& aSmartPtr)
+    : NSCAP_CTOR_BASE(aSmartPtr.mRawPtr)
+  {
+    assert_validity();
+    if (mRawPtr) {
+      NSCAP_ADDREF(this, mRawPtr);
+    }
+    NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.mRawPtr);
+  }
+
+  nsCOMPtr(nsCOMPtr<T>&& aSmartPtr)
+    : NSCAP_CTOR_BASE(aSmartPtr.mRawPtr)
+  {
+    assert_validity();
+    aSmartPtr.mRawPtr = nullptr;
+    NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  MOZ_IMPLICIT nsCOMPtr(T* aRawPtr)
+    : NSCAP_CTOR_BASE(aRawPtr)
+  {
+    assert_validity();
+    if (mRawPtr) {
+      NSCAP_ADDREF(this, mRawPtr);
+    }
+    NSCAP_LOG_ASSIGNMENT(this, aRawPtr);
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<T>& aSmartPtr)
+    : NSCAP_CTOR_BASE(aSmartPtr.take())
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  // Construct from |otherComPtr.forget()|.
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<T>&& aSmartPtr)
+    : NSCAP_CTOR_BASE(aSmartPtr.take())
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  // Construct from |already_AddRefed|.
+  template<typename U>
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<U>& aSmartPtr)
+    : NSCAP_CTOR_BASE(static_cast<T*>(aSmartPtr.take()))
+  {
+    assert_validity();
+    // But make sure that U actually inherits from T.
+    static_assert(mozilla::IsBaseOf<T, U>::value,
+                  "U is not a subclass of T");
+    NSCAP_LOG_ASSIGNMENT(this, static_cast<T*>(mRawPtr));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  // Construct from |otherComPtr.forget()|.
+  template<typename U>
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<U>&& aSmartPtr)
+    : NSCAP_CTOR_BASE(static_cast<T*>(aSmartPtr.take()))
+  {
+    assert_validity();
+    // But make sure that U actually inherits from T.
+    static_assert(mozilla::IsBaseOf<T, U>::value,
+                  "U is not a subclass of T");
+    NSCAP_LOG_ASSIGNMENT(this, static_cast<T*>(mRawPtr));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  // Construct from |do_QueryInterface(expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsQueryInterface aQI)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_qi(aQI, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // Construct from |do_QueryInterface(expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsQueryInterfaceWithError& aQI)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_qi_with_error(aQI, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // Construct from |do_GetService(cid_expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCID aGS)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_cid(aGS, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // Construct from |do_GetService(cid_expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCIDWithError& aGS)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_cid_with_error(aGS, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // Construct from |do_GetService(contractid_expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractID aGS)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_contractid(aGS, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // Construct from |do_GetService(contractid_expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractIDWithError& aGS)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_contractid_with_error(aGS, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // And finally, anything else we might need to construct from can exploit the
+  // nsCOMPtr_helper facility.
+  MOZ_IMPLICIT nsCOMPtr(const nsCOMPtr_helper& aHelper)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_helper(aHelper, NS_GET_TEMPLATE_IID(T));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  // Defined in OwningNonNull.h
+  template<class U>
+  MOZ_IMPLICIT nsCOMPtr(const mozilla::OwningNonNull<U>& aOther);
+
+
+  // Assignment operators
+
+  nsCOMPtr<T>& operator=(const nsCOMPtr<T>& aRhs)
+  {
+    assign_with_AddRef(aRhs.mRawPtr);
+    return *this;
+  }
+
+  nsCOMPtr<T>& operator=(T* aRhs)
+  {
+    assign_with_AddRef(aRhs);
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+    return *this;
+  }
+
+  nsCOMPtr<T>& operator=(decltype(nullptr))
+  {
+    assign_assuming_AddRef(nullptr);
+    return *this;
+  }
+
+  // Assign from |already_AddRefed|.
+  template<typename U>
+  nsCOMPtr<T>& operator=(already_AddRefed<U>& aRhs)
+  {
+    // Make sure that U actually inherits from T
+    static_assert(mozilla::IsBaseOf<T, U>::value,
+                  "U is not a subclass of T");
+    assign_assuming_AddRef(static_cast<T*>(aRhs.take()));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+    return *this;
+  }
+
+  // Assign from |otherComPtr.forget()|.
+  template<typename U>
+  nsCOMPtr<T>& operator=(already_AddRefed<U>&& aRhs)
+  {
+    // Make sure that U actually inherits from T
+    static_assert(mozilla::IsBaseOf<T, U>::value,
+                  "U is not a subclass of T");
+    assign_assuming_AddRef(static_cast<T*>(aRhs.take()));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+    return *this;
+  }
+
+  // Assign from |do_QueryInterface(expr)|.
+  nsCOMPtr<T>& operator=(const nsQueryInterface aRhs)
+  {
+    assign_from_qi(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // Assign from |do_QueryInterface(expr, &rv)|.
+  nsCOMPtr<T>& operator=(const nsQueryInterfaceWithError& aRhs)
+  {
+    assign_from_qi_with_error(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // Assign from |do_GetService(cid_expr)|.
+  nsCOMPtr<T>& operator=(const nsGetServiceByCID aRhs)
+  {
+    assign_from_gs_cid(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // Assign from |do_GetService(cid_expr, &rv)|.
+  nsCOMPtr<T>& operator=(const nsGetServiceByCIDWithError& aRhs)
+  {
+    assign_from_gs_cid_with_error(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // Assign from |do_GetService(contractid_expr)|.
+  nsCOMPtr<T>& operator=(const nsGetServiceByContractID aRhs)
+  {
+    assign_from_gs_contractid(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // Assign from |do_GetService(contractid_expr, &rv)|.
+  nsCOMPtr<T>& operator=(const nsGetServiceByContractIDWithError& aRhs)
+  {
+    assign_from_gs_contractid_with_error(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // And finally, anything else we might need to assign from can exploit the
+  // nsCOMPtr_helper facility.
+  nsCOMPtr<T>& operator=(const nsCOMPtr_helper& aRhs)
+  {
+    assign_from_helper(aRhs, NS_GET_TEMPLATE_IID(T));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+    return *this;
+  }
+
+  // Defined in OwningNonNull.h
+  template<class U>
+  nsCOMPtr<T>& operator=(const mozilla::OwningNonNull<U>& aOther);
+
+  // Exchange ownership with |aRhs|; can save a pair of refcount operations.
+  void swap(nsCOMPtr<T>& aRhs)
+  {
+#ifdef NSCAP_FEATURE_USE_BASE
+    nsISupports* temp = aRhs.mRawPtr;
+#else
+    T* temp = aRhs.mRawPtr;
+#endif
+    NSCAP_LOG_ASSIGNMENT(&aRhs, mRawPtr);
+    NSCAP_LOG_ASSIGNMENT(this, temp);
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    NSCAP_LOG_RELEASE(&aRhs, temp);
+    aRhs.mRawPtr = mRawPtr;
+    mRawPtr = temp;
+    // |aRhs| maintains the same invariants, so we don't need to |NSCAP_ASSERT_NO_QUERY_NEEDED|
+  }
+
+  // Exchange ownership with |aRhs|; can save a pair of refcount operations.
+  void swap(T*& aRhs)
+  {
+#ifdef NSCAP_FEATURE_USE_BASE
+    nsISupports* temp = aRhs;
+#else
+    T* temp = aRhs;
+#endif
+    NSCAP_LOG_ASSIGNMENT(this, temp);
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    aRhs = reinterpret_cast<T*>(mRawPtr);
+    mRawPtr = temp;
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+
+  // Other pointer operators
+
+  // Return the value of mRawPtr and null out mRawPtr. Useful for
+  // already_AddRefed return values.
+  already_AddRefed<T> forget()
+  {
+    T* temp = nullptr;
+    swap(temp);
+    return already_AddRefed<T>(temp);
+  }
+
+  // Set the target of aRhs to the value of mRawPtr and null out mRawPtr.
+  // Useful to avoid unnecessary AddRef/Release pairs with "out" parameters
+  // where aRhs bay be a T** or an I** where I is a base class of T.
+  template<typename I>
+  void forget(I** aRhs)
+  {
+    NS_ASSERTION(aRhs, "Null pointer passed to forget!");
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    *aRhs = get();
+    mRawPtr = nullptr;
+  }
+
+  // Prefer the implicit conversion provided automatically by
+  // |operator T*() const|. Use |get()| to resolve ambiguity or to get a
+  // castable pointer.
+  T* get() const { return reinterpret_cast<T*>(mRawPtr); }
+
+  // Makes an nsCOMPtr act like its underlying raw pointer type whenever it is
+  // used in a context where a raw pointer is expected. It is this operator
+  // that makes an nsCOMPtr substitutable for a raw pointer.
+  //
+  // Prefer the implicit use of this operator to calling |get()|, except where
+  // necessary to resolve ambiguity.
+  operator T*() const
+#ifdef MOZ_HAVE_REF_QUALIFIERS
+  &
+#endif
+  { return get(); }
+
+#ifdef MOZ_HAVE_REF_QUALIFIERS
+  // Don't allow implicit conversion of temporary nsCOMPtr to raw pointer,
+  // because the refcount might be one and the pointer will immediately become
+  // invalid.
+  operator T*() const && = delete;
+
+  // Needed to avoid the deleted operator above
+  explicit operator bool() const { return !!mRawPtr; }
+#endif
+
+  T* operator->() const MOZ_NO_ADDREF_RELEASE_ON_RETURN
+  {
+    MOZ_ASSERT(mRawPtr != nullptr,
+               "You can't dereference a NULL nsCOMPtr with operator->().");
+    return get();
+  }
+
+  // These are not intended to be used by clients. See |address_of| below.
+  nsCOMPtr<T>* get_address() { return this; }
+  const nsCOMPtr<T>* get_address() const { return this; }
+
+public:
+  T& operator*() const
+  {
+    MOZ_ASSERT(mRawPtr != nullptr,
+               "You can't dereference a NULL nsCOMPtr with operator*().");
+    return *get();
+  }
+
+  T** StartAssignment()
+  {
+#ifndef NSCAP_FEATURE_INLINE_STARTASSIGNMENT
+    return reinterpret_cast<T**>(begin_assignment());
+#else
+    assign_assuming_AddRef(nullptr);
+    return reinterpret_cast<T**>(&mRawPtr);
+#endif
+  }
+};
+
+
+/*
+ * Specializing nsCOMPtr for nsISupports allows us to use nsCOMPtr<nsISupports>
+ * the same way people use nsISupports* and void*, i.e., as a `catch-all'
+ * pointing to any valid [XP]COM interface. Otherwise, an nsCOMPtr<nsISupports>
+ * would only be able to point to the single [XP]COM-correct nsISupports
+ * instance within an object; extra querying ensues. Clients need to be able to
+ * pass around arbitrary interface pointers, without hassles, through
+ * intermediary code that doesn't know the exact type.
+ */
+template<>
+class nsCOMPtr<nsISupports>
+  : private nsCOMPtr_base
+{
+public:
+  typedef nsISupports element_type;
+
+  // Constructors
+
+  nsCOMPtr()
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+  }
+
+  MOZ_IMPLICIT nsCOMPtr(decltype(nullptr))
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+  }
+
+  nsCOMPtr(const nsCOMPtr<nsISupports>& aSmartPtr)
+    : nsCOMPtr_base(aSmartPtr.mRawPtr)
+  {
+    if (mRawPtr) {
+      NSCAP_ADDREF(this, mRawPtr);
+    }
+    NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.mRawPtr);
+  }
+
+  MOZ_IMPLICIT nsCOMPtr(nsISupports* aRawPtr)
+    : nsCOMPtr_base(aRawPtr)
+  {
+    if (mRawPtr) {
+      NSCAP_ADDREF(this, mRawPtr);
+    }
+    NSCAP_LOG_ASSIGNMENT(this, aRawPtr);
+  }
+
+  // Construct from |already_AddRefed|.
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<nsISupports>& aSmartPtr)
+    : nsCOMPtr_base(aSmartPtr.take())
+  {
+    NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
+  }
+
+  // Construct from |otherComPtr.forget()|.
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<nsISupports>&& aSmartPtr)
+    : nsCOMPtr_base(aSmartPtr.take())
+  {
+    NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
+  }
+
+  // Construct from |do_QueryInterface(expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsQueryInterface aQI)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_qi(aQI, NS_GET_IID(nsISupports));
+  }
+
+  // Construct from |do_QueryInterface(expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsQueryInterfaceWithError& aQI)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_qi_with_error(aQI, NS_GET_IID(nsISupports));
+  }
+
+  // Construct from |do_GetService(cid_expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCID aGS)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_cid(aGS, NS_GET_IID(nsISupports));
+  }
+
+  // Construct from |do_GetService(cid_expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCIDWithError& aGS)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_cid_with_error(aGS, NS_GET_IID(nsISupports));
+  }
+
+  // Construct from |do_GetService(contractid_expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractID aGS)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_contractid(aGS, NS_GET_IID(nsISupports));
+  }
+
+  // Construct from |do_GetService(contractid_expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractIDWithError& aGS)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_contractid_with_error(aGS, NS_GET_IID(nsISupports));
+  }
+
+  // And finally, anything else we might need to construct from can exploit
+  // the |nsCOMPtr_helper| facility
+  MOZ_IMPLICIT nsCOMPtr(const nsCOMPtr_helper& aHelper)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_helper(aHelper, NS_GET_IID(nsISupports));
+  }
+
+
+  // Assignment operators
+
+  nsCOMPtr<nsISupports>& operator=(const nsCOMPtr<nsISupports>& aRhs)
+  {
+    assign_with_AddRef(aRhs.mRawPtr);
+    return *this;
+  }
+
+  nsCOMPtr<nsISupports>& operator=(nsISupports* aRhs)
+  {
+    assign_with_AddRef(aRhs);
+    return *this;
+  }
+
+  nsCOMPtr<nsISupports>& operator=(decltype(nullptr))
+  {
+    assign_assuming_AddRef(nullptr);
+    return *this;
+  }
+
+  // Assign from |already_AddRefed|.
+  nsCOMPtr<nsISupports>& operator=(already_AddRefed<nsISupports>& aRhs)
+  {
+    assign_assuming_AddRef(aRhs.take());
+    return *this;
+  }
+
+  // Assign from |otherComPtr.forget()|.
+  nsCOMPtr<nsISupports>& operator=(already_AddRefed<nsISupports>&& aRhs)
+  {
+    assign_assuming_AddRef(aRhs.take());
+    return *this;
+  }
+
+  // Assign from |do_QueryInterface(expr)|.
+  nsCOMPtr<nsISupports>& operator=(const nsQueryInterface aRhs)
+  {
+    assign_from_qi(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Assign from |do_QueryInterface(expr, &rv)|.
+  nsCOMPtr<nsISupports>& operator=(const nsQueryInterfaceWithError& aRhs)
+  {
+    assign_from_qi_with_error(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Assign from |do_GetService(cid_expr)|.
+  nsCOMPtr<nsISupports>& operator=(const nsGetServiceByCID aRhs)
+  {
+    assign_from_gs_cid(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Assign from |do_GetService(cid_expr, &rv)|.
+  nsCOMPtr<nsISupports>& operator=(const nsGetServiceByCIDWithError& aRhs)
+  {
+    assign_from_gs_cid_with_error(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Assign from |do_GetService(contractid_expr)|.
+  nsCOMPtr<nsISupports>& operator=(const nsGetServiceByContractID aRhs)
+  {
+    assign_from_gs_contractid(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Assign from |do_GetService(contractid_expr, &rv)|.
+  nsCOMPtr<nsISupports>& operator=(const nsGetServiceByContractIDWithError& aRhs)
+  {
+    assign_from_gs_contractid_with_error(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // And finally, anything else we might need to assign from can exploit the
+  // nsCOMPtr_helper facility
+  nsCOMPtr<nsISupports>& operator=(const nsCOMPtr_helper& aRhs)
+  {
+    assign_from_helper(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Exchange ownership with |aRhs|; can save a pair of refcount operations.
+  void swap(nsCOMPtr<nsISupports>& aRhs)
+  {
+    nsISupports* temp = aRhs.mRawPtr;
+    NSCAP_LOG_ASSIGNMENT(&aRhs, mRawPtr);
+    NSCAP_LOG_ASSIGNMENT(this, temp);
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    NSCAP_LOG_RELEASE(&aRhs, temp);
+    aRhs.mRawPtr = mRawPtr;
+    mRawPtr = temp;
+  }
+
+  // Exchange ownership with |aRhs|; can save a pair of refcount operations.
+  void swap(nsISupports*& aRhs)
+  {
+    nsISupports* temp = aRhs;
+    NSCAP_LOG_ASSIGNMENT(this, temp);
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    aRhs = mRawPtr;
+    mRawPtr = temp;
+  }
+
+  // Return the value of mRawPtr and null out mRawPtr. Useful for
+  // already_AddRefed return values.
+  already_AddRefed<nsISupports> forget()
+  {
+    nsISupports* temp = nullptr;
+    swap(temp);
+    return already_AddRefed<nsISupports>(temp);
+  }
+
+  // Set the target of aRhs to the value of mRawPtr and null out mRawPtr.
+  // Useful to avoid unnecessary AddRef/Release pairs with "out"
+  // parameters.
+  void forget(nsISupports** aRhs)
+  {
+    NS_ASSERTION(aRhs, "Null pointer passed to forget!");
+    *aRhs = nullptr;
+    swap(*aRhs);
+  }
+
+  // Other pointer operators
+
+  // Prefer the implicit conversion provided automatically by
+  // |operator nsISupports*() const|. Use |get()| to resolve ambiguity or to
+  // get a castable pointer.
+  nsISupports* get() const { return reinterpret_cast<nsISupports*>(mRawPtr); }
+
+  // Makes an nsCOMPtr act like its underlying raw pointer type whenever it is
+  // used in a context where a raw pointer is expected. It is this operator
+  // that makes an nsCOMPtr substitutable for a raw pointer.
+  //
+  // Prefer the implicit use of this operator to calling |get()|, except where
+  // necessary to resolve ambiguity/
+  operator nsISupports* () const { return get(); }
+
+  nsISupports* operator->() const MOZ_NO_ADDREF_RELEASE_ON_RETURN
+  {
+    MOZ_ASSERT(mRawPtr != nullptr,
+               "You can't dereference a NULL nsCOMPtr with operator->().");
+    return get();
+  }
+
+  // These are not intended to be used by clients. See |address_of| below.
+  nsCOMPtr<nsISupports>* get_address() { return this; }
+  const nsCOMPtr<nsISupports>* get_address() const { return this; }
+
+public:
+
+  nsISupports& operator*() const
+  {
+    MOZ_ASSERT(mRawPtr != nullptr,
+               "You can't dereference a NULL nsCOMPtr with operator*().");
+    return *get();
+  }
+
+  nsISupports** StartAssignment()
+  {
+#ifndef NSCAP_FEATURE_INLINE_STARTASSIGNMENT
+    return reinterpret_cast<nsISupports**>(begin_assignment());
+#else
+    assign_assuming_AddRef(nullptr);
+    return reinterpret_cast<nsISupports**>(&mRawPtr);
+#endif
+  }
+};
+
+template<typename T>
+inline void
+ImplCycleCollectionUnlink(nsCOMPtr<T>& aField)
+{
+  aField = nullptr;
+}
+
+template<typename T>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsCOMPtr<T>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  CycleCollectionNoteChild(aCallback, aField.get(), aName, aFlags);
+}
+
+#ifndef NSCAP_FEATURE_USE_BASE
+template<class T>
+void
+nsCOMPtr<T>::assign_with_AddRef(nsISupports* aRawPtr)
+{
+  if (aRawPtr) {
+    NSCAP_ADDREF(this, aRawPtr);
+  }
+  assign_assuming_AddRef(reinterpret_cast<T*>(aRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_qi(const nsQueryInterface aQI, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aQI(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_qi_with_error(const nsQueryInterfaceWithError& aQI,
+                                       const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aQI(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_gs_cid(const nsGetServiceByCID aGS, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_gs_cid_with_error(const nsGetServiceByCIDWithError& aGS,
+                                           const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_gs_contractid(const nsGetServiceByContractID aGS,
+                                       const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_gs_contractid_with_error(
+    const nsGetServiceByContractIDWithError& aGS, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_helper(const nsCOMPtr_helper& helper, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(helper(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void**
+nsCOMPtr<T>::begin_assignment()
+{
+  assign_assuming_AddRef(nullptr);
+  union
+  {
+    T** mT;
+    void** mVoid;
+  } result;
+  result.mT = &mRawPtr;
+  return result.mVoid;
+}
+#endif
+
+template<class T>
+inline nsCOMPtr<T>*
+address_of(nsCOMPtr<T>& aPtr)
+{
+  return aPtr.get_address();
+}
+
+template<class T>
+inline const nsCOMPtr<T>*
+address_of(const nsCOMPtr<T>& aPtr)
+{
+  return aPtr.get_address();
+}
+
+/**
+ * This class is designed to be used for anonymous temporary objects in the
+ * argument list of calls that return COM interface pointers, e.g.,
+ *
+ *   nsCOMPtr<IFoo> fooP;
+ *   ...->QueryInterface(iid, getter_AddRefs(fooP))
+ *
+ * DO NOT USE THIS TYPE DIRECTLY IN YOUR CODE. Use |getter_AddRefs()| instead.
+ *
+ * When initialized with a |nsCOMPtr|, as in the example above, it returns
+ * a |void**|, a |T**|, or an |nsISupports**| as needed, that the outer call
+ * (|QueryInterface| in this case) can fill in.
+ *
+ * This type should be a nested class inside |nsCOMPtr<T>|.
+ */
+template<class T>
+class nsGetterAddRefs
+{
+public:
+  explicit nsGetterAddRefs(nsCOMPtr<T>& aSmartPtr)
+    : mTargetSmartPtr(aSmartPtr)
+  {
+  }
+
+#if defined(NSCAP_FEATURE_TEST_DONTQUERY_CASES) || defined(NSCAP_LOG_EXTERNAL_ASSIGNMENT)
+  ~nsGetterAddRefs()
+  {
+#ifdef NSCAP_LOG_EXTERNAL_ASSIGNMENT
+    NSCAP_LOG_ASSIGNMENT(reinterpret_cast<void*>(address_of(mTargetSmartPtr)),
+                         mTargetSmartPtr.get());
+#endif
+
+#ifdef NSCAP_FEATURE_TEST_DONTQUERY_CASES
+    mTargetSmartPtr.Assert_NoQueryNeeded();
+#endif
+  }
+#endif
+
+  operator void**()
+  {
+    return reinterpret_cast<void**>(mTargetSmartPtr.StartAssignment());
+  }
+
+  operator T**() { return mTargetSmartPtr.StartAssignment(); }
+  T*& operator*() { return *(mTargetSmartPtr.StartAssignment()); }
+
+private:
+  nsCOMPtr<T>& mTargetSmartPtr;
+};
+
+
+template<>
+class nsGetterAddRefs<nsISupports>
+{
+public:
+  explicit nsGetterAddRefs(nsCOMPtr<nsISupports>& aSmartPtr)
+    : mTargetSmartPtr(aSmartPtr)
+  {
+  }
+
+#ifdef NSCAP_LOG_EXTERNAL_ASSIGNMENT
+  ~nsGetterAddRefs()
+  {
+    NSCAP_LOG_ASSIGNMENT(reinterpret_cast<void*>(address_of(mTargetSmartPtr)),
+                         mTargetSmartPtr.get());
+  }
+#endif
+
+  operator void**()
+  {
+    return reinterpret_cast<void**>(mTargetSmartPtr.StartAssignment());
+  }
+
+  operator nsISupports**() { return mTargetSmartPtr.StartAssignment(); }
+  nsISupports*& operator*() { return *(mTargetSmartPtr.StartAssignment()); }
+
+private:
+  nsCOMPtr<nsISupports>& mTargetSmartPtr;
+};
+
+template<class T>
+inline nsGetterAddRefs<T>
+getter_AddRefs(nsCOMPtr<T>& aSmartPtr)
+{
+  return nsGetterAddRefs<T>(aSmartPtr);
+}
+
+template<class T, class DestinationType>
+inline nsresult
+CallQueryInterface(T* aSource, nsGetterAddRefs<DestinationType> aDestination)
+{
+  return CallQueryInterface(aSource,
+                            static_cast<DestinationType**>(aDestination));
+}
+
+
+// Comparing two |nsCOMPtr|s
+
+template<class T, class U>
+inline bool
+operator==(const nsCOMPtr<T>& aLhs, const nsCOMPtr<U>& aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) == static_cast<const U*>(aRhs.get());
+}
+
+
+template<class T, class U>
+inline bool
+operator!=(const nsCOMPtr<T>& aLhs, const nsCOMPtr<U>& aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) != static_cast<const U*>(aRhs.get());
+}
+
+
+// Comparing an |nsCOMPtr| to a raw pointer
+
+template<class T, class U>
+inline bool
+operator==(const nsCOMPtr<T>& aLhs, const U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) == aRhs;
+}
+
+template<class T, class U>
+inline bool
+operator==(const U* aLhs, const nsCOMPtr<T>& aRhs)
+{
+  return aLhs == static_cast<const T*>(aRhs.get());
+}
+
+template<class T, class U>
+inline bool
+operator!=(const nsCOMPtr<T>& aLhs, const U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) != aRhs;
+}
+
+template<class T, class U>
+inline bool
+operator!=(const U* aLhs, const nsCOMPtr<T>& aRhs)
+{
+  return aLhs != static_cast<const T*>(aRhs.get());
+}
+
+template<class T, class U>
+inline bool
+operator==(const nsCOMPtr<T>& aLhs, U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) == const_cast<const U*>(aRhs);
+}
+
+template<class T, class U>
+inline bool
+operator==(U* aLhs, const nsCOMPtr<T>& aRhs)
+{
+  return const_cast<const U*>(aLhs) == static_cast<const T*>(aRhs.get());
+}
+
+template<class T, class U>
+inline bool
+operator!=(const nsCOMPtr<T>& aLhs, U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) != const_cast<const U*>(aRhs);
+}
+
+template<class T, class U>
+inline bool
+operator!=(U* aLhs, const nsCOMPtr<T>& aRhs)
+{
+  return const_cast<const U*>(aLhs) != static_cast<const T*>(aRhs.get());
+}
+
+
+
+// Comparing an |nsCOMPtr| to |nullptr|
+
+template<class T>
+inline bool
+operator==(const nsCOMPtr<T>& aLhs, decltype(nullptr))
+{
+  return aLhs.get() == nullptr;
+}
+
+template<class T>
+inline bool
+operator==(decltype(nullptr), const nsCOMPtr<T>& aRhs)
+{
+  return nullptr == aRhs.get();
+}
+
+template<class T>
+inline bool
+operator!=(const nsCOMPtr<T>& aLhs, decltype(nullptr))
+{
+  return aLhs.get() != nullptr;
+}
+
+template<class T>
+inline bool
+operator!=(decltype(nullptr), const nsCOMPtr<T>& aRhs)
+{
+  return nullptr != aRhs.get();
+}
+
+
+// Comparing any two [XP]COM objects for identity
+
+inline bool
+SameCOMIdentity(nsISupports* aLhs, nsISupports* aRhs)
+{
+  return nsCOMPtr<nsISupports>(do_QueryInterface(aLhs)) ==
+    nsCOMPtr<nsISupports>(do_QueryInterface(aRhs));
+}
+
+
+
+template<class SourceType, class DestinationType>
+inline nsresult
+CallQueryInterface(nsCOMPtr<SourceType>& aSourcePtr, DestinationType** aDestPtr)
+{
+  return CallQueryInterface(aSourcePtr.get(), aDestPtr);
+}
+
+template <class T>
+RefPtr<T>::RefPtr(const nsCOMPtr_helper& aHelper)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aHelper(NS_GET_TEMPLATE_IID(T), &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  mRawPtr = static_cast<T*>(newRawPtr);
+}
+
+template <class T>
+RefPtr<T>&
+RefPtr<T>::operator=(const nsCOMPtr_helper& aHelper)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aHelper(NS_GET_TEMPLATE_IID(T), &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+  return *this;
+}
+
+
+#endif // !defined(nsCOMPtr_h___)
diff --git a/xpcom/glue/nsCRTGlue.cpp b/xpcom/glue/nsCRTGlue.cpp
new file mode 100644
index 0000000000..7a9f6db030
--- /dev/null
+++ b/xpcom/glue/nsCRTGlue.cpp
@@ -0,0 +1,441 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCRTGlue.h"
+#include "nsXPCOM.h"
+#include "nsDebug.h"
+#include "prtime.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdarg.h>
+
+#include "mozilla/Sprintf.h"
+
+#ifdef XP_WIN
+#include <io.h>
+#include <windows.h>
+#include "mozilla/UniquePtr.h"
+#endif
+
+#ifdef ANDROID
+#include <android/log.h>
+#include <unistd.h>
+#endif
+
+using namespace mozilla;
+
+const char*
+NS_strspnp(const char* aDelims, const char* aStr)
+{
+  const char* d;
+  do {
+    for (d = aDelims; *d != '\0'; ++d) {
+      if (*aStr == *d) {
+        ++aStr;
+        break;
+      }
+    }
+  } while (*d);
+
+  return aStr;
+}
+
+char*
+NS_strtok(const char* aDelims, char** aStr)
+{
+  if (!*aStr) {
+    return nullptr;
+  }
+
+  char* ret = (char*)NS_strspnp(aDelims, *aStr);
+
+  if (!*ret) {
+    *aStr = ret;
+    return nullptr;
+  }
+
+  char* i = ret;
+  do {
+    for (const char* d = aDelims; *d != '\0'; ++d) {
+      if (*i == *d) {
+        *i = '\0';
+        *aStr = ++i;
+        return ret;
+      }
+    }
+    ++i;
+  } while (*i);
+
+  *aStr = nullptr;
+  return ret;
+}
+
+uint32_t
+NS_strlen(const char16_t* aString)
+{
+  MOZ_ASSERT(aString);
+  const char16_t* end;
+
+  for (end = aString; *end; ++end) {
+    // empty loop
+  }
+
+  return end - aString;
+}
+
+int
+NS_strcmp(const char16_t* aStrA, const char16_t* aStrB)
+{
+  while (*aStrB) {
+    int r = *aStrA - *aStrB;
+    if (r) {
+      return r;
+    }
+
+    ++aStrA;
+    ++aStrB;
+  }
+
+  return *aStrA != '\0';
+}
+
+int
+NS_strncmp(const char16_t* aStrA, const char16_t* aStrB, size_t aLen)
+{
+  while (aLen && *aStrB) {
+    int r = *aStrA - *aStrB;
+    if (r) {
+      return r;
+    }
+
+    ++aStrA;
+    ++aStrB;
+    --aLen;
+  }
+
+  return aLen ? *aStrA != '\0' : *aStrA - *aStrB;
+}
+
+char16_t*
+NS_strdup(const char16_t* aString)
+{
+  uint32_t len = NS_strlen(aString);
+  return NS_strndup(aString, len);
+}
+
+template<typename CharT>
+CharT*
+NS_strndup(const CharT* aString, uint32_t aLen)
+{
+  auto newBuf = (CharT*)NS_Alloc((aLen + 1) * sizeof(CharT));
+  if (newBuf) {
+    memcpy(newBuf, aString, aLen * sizeof(CharT));
+    newBuf[aLen] = '\0';
+  }
+  return newBuf;
+}
+
+template char16_t* NS_strndup<char16_t>(const char16_t* aString, uint32_t aLen);
+template char* NS_strndup<char>(const char* aString, uint32_t aLen);
+
+char*
+NS_strdup(const char* aString)
+{
+  uint32_t len = strlen(aString);
+  char* str = (char*)NS_Alloc(len + 1);
+  if (str) {
+    memcpy(str, aString, len);
+    str[len] = '\0';
+  }
+  return str;
+}
+
+// This table maps uppercase characters to lower case characters;
+// characters that are neither upper nor lower case are unaffected.
+const unsigned char nsLowerUpperUtils::kUpper2Lower[256] = {
+    0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15,
+   16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+   32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
+   48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
+   64,
+
+    // upper band mapped to lower [A-Z] => [a-z]
+       97, 98, 99,100,101,102,103,104,105,106,107,108,109,110,111,
+  112,113,114,115,116,117,118,119,120,121,122,
+
+                                               91, 92, 93, 94, 95,
+   96, 97, 98, 99,100,101,102,103,104,105,106,107,108,109,110,111,
+  112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,
+  128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
+  144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,
+  160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,
+  176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,
+  192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,
+  208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,
+  224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,
+  240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255
+};
+
+const unsigned char nsLowerUpperUtils::kLower2Upper[256] = {
+    0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15,
+   16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+   32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
+   48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
+   64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
+   80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
+   96,
+
+    // lower band mapped to upper [a-z] => [A-Z]
+       65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
+   80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90,
+
+                                              123,124,125,126,127,
+  128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
+  144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,
+  160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,
+  176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,
+  192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,
+  208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,
+  224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,
+  240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255
+};
+
+bool
+NS_IsUpper(char aChar)
+{
+  return aChar != (char)nsLowerUpperUtils::kUpper2Lower[(unsigned char)aChar];
+}
+
+bool
+NS_IsLower(char aChar)
+{
+  return aChar != (char)nsLowerUpperUtils::kLower2Upper[(unsigned char)aChar];
+}
+
+bool
+NS_IsAscii(char16_t aChar)
+{
+  return (0x0080 > aChar);
+}
+
+bool
+NS_IsAscii(const char16_t* aString)
+{
+  while (*aString) {
+    if (0x0080 <= *aString) {
+      return false;
+    }
+    aString++;
+  }
+  return true;
+}
+
+bool
+NS_IsAscii(const char* aString)
+{
+  while (*aString) {
+    if (0x80 & *aString) {
+      return false;
+    }
+    aString++;
+  }
+  return true;
+}
+
+bool
+NS_IsAscii(const char* aString, uint32_t aLength)
+{
+  const char* end = aString + aLength;
+  while (aString < end) {
+    if (0x80 & *aString) {
+      return false;
+    }
+    ++aString;
+  }
+  return true;
+}
+
+bool
+NS_IsAsciiAlpha(char16_t aChar)
+{
+  return (aChar >= 'A' && aChar <= 'Z') ||
+         (aChar >= 'a' && aChar <= 'z');
+}
+
+bool
+NS_IsAsciiWhitespace(char16_t aChar)
+{
+  return aChar == ' ' ||
+         aChar == '\r' ||
+         aChar == '\n' ||
+         aChar == '\t';
+}
+
+bool
+NS_IsAsciiDigit(char16_t aChar)
+{
+  return aChar >= '0' && aChar <= '9';
+}
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+
+void
+NS_MakeRandomString(char* aBuf, int32_t aBufLen)
+{
+#define TABLE_SIZE 36
+  static const char table[] = {
+    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
+    'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
+    'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3',
+    '4', '5', '6', '7', '8', '9'
+  };
+
+  // turn PR_Now() into milliseconds since epoch
+  // and salt rand with that.
+  static unsigned int seed = 0;
+  if (seed == 0) {
+    double fpTime = double(PR_Now());
+    seed = (unsigned int)(fpTime * 1e-6 + 0.5); // use 1e-6, granularity of PR_Now() on the mac is seconds
+    srand(seed);
+  }
+
+  int32_t i;
+  for (i = 0; i < aBufLen; ++i) {
+    *aBuf++ = table[rand() % TABLE_SIZE];
+  }
+  *aBuf = 0;
+}
+
+#endif
+
+static StderrCallback sStderrCallback = nullptr;
+
+void
+set_stderr_callback(StderrCallback aCallback)
+{
+  sStderrCallback = aCallback;
+}
+
+#if defined(ANDROID) && !defined(RELEASE_OR_BETA)
+static FILE* sStderrCopy = nullptr;
+
+void
+stderr_to_file(const char* aFmt, va_list aArgs)
+{
+  vfprintf(sStderrCopy, aFmt, aArgs);
+}
+
+void
+copy_stderr_to_file(const char* aFile)
+{
+  if (sStderrCopy) {
+    return;
+  }
+  size_t buflen = strlen(aFile) + 16;
+  char* buf = (char*)malloc(buflen);
+  snprintf(buf, buflen, "%s.%u", aFile, (uint32_t)getpid());
+  sStderrCopy = fopen(buf, "w");
+  free(buf);
+  set_stderr_callback(stderr_to_file);
+}
+#endif
+
+#ifdef HAVE_VA_COPY
+#define VARARGS_ASSIGN(foo, bar)        VA_COPY(foo,bar)
+#elif defined(HAVE_VA_LIST_AS_ARRAY)
+#define VARARGS_ASSIGN(foo, bar)     foo[0] = bar[0]
+#else
+#define VARARGS_ASSIGN(foo, bar)     (foo) = (bar)
+#endif
+
+#if defined(XP_WIN)
+void
+vprintf_stderr(const char* aFmt, va_list aArgs)
+{
+  if (sStderrCallback) {
+    va_list argsCpy;
+    VARARGS_ASSIGN(argsCpy, aArgs);
+    sStderrCallback(aFmt, aArgs);
+    va_end(argsCpy);
+  }
+
+  if (IsDebuggerPresent()) {
+    int lengthNeeded = _vscprintf(aFmt, aArgs);
+    if (lengthNeeded) {
+      lengthNeeded++;
+      auto buf = MakeUnique<char[]>(lengthNeeded);
+      if (buf) {
+        va_list argsCpy;
+        VARARGS_ASSIGN(argsCpy, aArgs);
+        vsnprintf(buf.get(), lengthNeeded, aFmt, argsCpy);
+        buf[lengthNeeded - 1] = '\0';
+        va_end(argsCpy);
+        OutputDebugStringA(buf.get());
+      }
+    }
+  }
+
+  FILE* fp = _fdopen(_dup(2), "a");
+  if (!fp) {
+    return;
+  }
+
+  vfprintf(fp, aFmt, aArgs);
+
+  fclose(fp);
+}
+
+#elif defined(ANDROID)
+void
+vprintf_stderr(const char* aFmt, va_list aArgs)
+{
+  if (sStderrCallback) {
+    va_list argsCpy;
+    VARARGS_ASSIGN(argsCpy, aArgs);
+    sStderrCallback(aFmt, aArgs);
+    va_end(argsCpy);
+  }
+
+  __android_log_vprint(ANDROID_LOG_INFO, "Gecko", aFmt, aArgs);
+}
+#else
+void
+vprintf_stderr(const char* aFmt, va_list aArgs)
+{
+  if (sStderrCallback) {
+    va_list argsCpy;
+    VARARGS_ASSIGN(argsCpy, aArgs);
+    sStderrCallback(aFmt, aArgs);
+    va_end(argsCpy);
+  }
+
+  vfprintf(stderr, aFmt, aArgs);
+}
+#endif
+
+void
+printf_stderr(const char* aFmt, ...)
+{
+  va_list args;
+  va_start(args, aFmt);
+  vprintf_stderr(aFmt, args);
+  va_end(args);
+}
+
+void
+fprintf_stderr(FILE* aFile, const char* aFmt, ...)
+{
+  va_list args;
+  va_start(args, aFmt);
+  if (aFile == stderr) {
+    vprintf_stderr(aFmt, args);
+  } else {
+    vfprintf(aFile, aFmt, args);
+  }
+  va_end(args);
+}
diff --git a/xpcom/glue/nsCRTGlue.h b/xpcom/glue/nsCRTGlue.h
new file mode 100644
index 0000000000..8caa1ae272
--- /dev/null
+++ b/xpcom/glue/nsCRTGlue.h
@@ -0,0 +1,147 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCRTGlue_h__
+#define nsCRTGlue_h__
+
+#include "nscore.h"
+
+/**
+ * Scan a string for the first character that is *not* in a set of
+ * delimiters.  If the string is only delimiter characters, the end of the
+ * string is returned.
+ *
+ * @param aDelims The set of delimiters (null-terminated)
+ * @param aStr    The string to search (null-terminated)
+ */
+const char* NS_strspnp(const char* aDelims, const char* aStr);
+
+/**
+ * Tokenize a string. This function is similar to the strtok function in the
+ * C standard library, but it does not use static variables to maintain state
+ * and is therefore thread and reentrancy-safe.
+ *
+ * Any leading delimiters in str are skipped. Then the string is scanned
+ * until an additional delimiter or end-of-string is found. The final
+ * delimiter is set to '\0'.
+ *
+ * @param aDelims The set of delimiters.
+ * @param aStr    The string to search. This is an in-out parameter; it is
+ *                reset to the end of the found token + 1, or to the
+ *                end-of-string if there are no more tokens.
+ * @return        The token. If no token is found (the string is only
+ *                delimiter characters), nullptr is returned.
+ */
+char* NS_strtok(const char* aDelims, char** aStr);
+
+/**
+ * "strlen" for char16_t strings
+ */
+uint32_t NS_strlen(const char16_t* aString);
+
+/**
+ * "strcmp" for char16_t strings
+ */
+int NS_strcmp(const char16_t* aStrA, const char16_t* aStrB);
+
+/**
+ * "strncmp" for char16_t strings
+ */
+int NS_strncmp(const char16_t* aStrA, const char16_t* aStrB, size_t aLen);
+
+/**
+ * "strdup" for char16_t strings, uses the NS_Alloc allocator.
+ */
+char16_t* NS_strdup(const char16_t* aString);
+
+/**
+ * "strdup", but using the NS_Alloc allocator.
+ */
+char* NS_strdup(const char* aString);
+
+/**
+ * strndup for char16_t or char strings (normal strndup is not available on
+ * windows). This function will ensure that the new string is
+ * null-terminated. Uses the NS_Alloc allocator.
+ *
+ * CharT may be either char16_t or char.
+ */
+template<typename CharT>
+CharT* NS_strndup(const CharT* aString, uint32_t aLen);
+
+// The following case-conversion methods only deal in the ascii repertoire
+// A-Z and a-z
+
+// semi-private data declarations... don't use these directly.
+class nsLowerUpperUtils
+{
+public:
+  static const unsigned char kLower2Upper[256];
+  static const unsigned char kUpper2Lower[256];
+};
+
+inline char
+NS_ToUpper(char aChar)
+{
+  return (char)nsLowerUpperUtils::kLower2Upper[(unsigned char)aChar];
+}
+
+inline char
+NS_ToLower(char aChar)
+{
+  return (char)nsLowerUpperUtils::kUpper2Lower[(unsigned char)aChar];
+}
+
+bool NS_IsUpper(char aChar);
+bool NS_IsLower(char aChar);
+
+bool NS_IsAscii(char16_t aChar);
+bool NS_IsAscii(const char16_t* aString);
+bool NS_IsAsciiAlpha(char16_t aChar);
+bool NS_IsAsciiDigit(char16_t aChar);
+bool NS_IsAsciiWhitespace(char16_t aChar);
+bool NS_IsAscii(const char* aString);
+bool NS_IsAscii(const char* aString, uint32_t aLength);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+void NS_MakeRandomString(char* aBuf, int32_t aBufLen);
+#endif
+
+#define FF '\f'
+#define TAB '\t'
+
+#define CRSTR "\015"
+#define LFSTR "\012"
+#define CRLF "\015\012"     /* A CR LF equivalent string */
+
+// We use the most restrictive filesystem as our default set of illegal filename
+// characters. This is currently Windows.
+#define OS_FILE_ILLEGAL_CHARACTERS "/:*?\"<>|"
+// We also provide a list of all known file path separators for all filesystems.
+// This can be used in replacement of FILE_PATH_SEPARATOR when you need to
+// identify or replace all known path separators.
+#define KNOWN_PATH_SEPARATORS "\\/"
+
+#if defined(XP_MACOSX)
+  #define FILE_PATH_SEPARATOR        "/"
+#elif defined(XP_WIN)
+  #define FILE_PATH_SEPARATOR        "\\"
+#elif defined(XP_UNIX)
+  #define FILE_PATH_SEPARATOR        "/"
+#else
+  #error need_to_define_your_file_path_separator_and_maybe_illegal_characters
+#endif
+
+// Not all these control characters are illegal in all OSs, but we don't really
+// want them appearing in filenames
+#define CONTROL_CHARACTERS     "\001\002\003\004\005\006\007" \
+                           "\010\011\012\013\014\015\016\017" \
+                           "\020\021\022\023\024\025\026\027" \
+                           "\030\031\032\033\034\035\036\037"
+
+#define FILE_ILLEGAL_CHARACTERS CONTROL_CHARACTERS OS_FILE_ILLEGAL_CHARACTERS
+
+#endif // nsCRTGlue_h__
diff --git a/xpcom/glue/nsCategoryCache.cpp b/xpcom/glue/nsCategoryCache.cpp
new file mode 100644
index 0000000000..30501b8e39
--- /dev/null
+++ b/xpcom/glue/nsCategoryCache.cpp
@@ -0,0 +1,149 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIObserverService.h"
+#include "mozilla/Services.h"
+#include "nsISupportsPrimitives.h"
+#include "nsIStringEnumerator.h"
+
+#include "nsXPCOMCID.h"
+
+#include "nsCategoryCache.h"
+
+nsCategoryObserver::nsCategoryObserver(const char* aCategory)
+  : mCategory(aCategory)
+  , mObserversRemoved(false)
+{
+  // First, enumerate the currently existing entries
+  nsCOMPtr<nsICategoryManager> catMan =
+    do_GetService(NS_CATEGORYMANAGER_CONTRACTID);
+  if (!catMan) {
+    return;
+  }
+
+  nsCOMPtr<nsISimpleEnumerator> enumerator;
+  nsresult rv = catMan->EnumerateCategory(aCategory,
+                                          getter_AddRefs(enumerator));
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  nsCOMPtr<nsIUTF8StringEnumerator> strings = do_QueryInterface(enumerator);
+  MOZ_ASSERT(strings);
+
+  bool more;
+  while (NS_SUCCEEDED(strings->HasMore(&more)) && more) {
+    nsAutoCString entryName;
+    strings->GetNext(entryName);
+
+    nsCString entryValue;
+    rv = catMan->GetCategoryEntry(aCategory,
+                                  entryName.get(),
+                                  getter_Copies(entryValue));
+    if (NS_SUCCEEDED(rv)) {
+      nsCOMPtr<nsISupports> service = do_GetService(entryValue.get());
+      if (service) {
+        mHash.Put(entryName, service);
+      }
+    }
+  }
+
+  // Now, listen for changes
+  nsCOMPtr<nsIObserverService> serv =
+    mozilla::services::GetObserverService();
+  if (serv) {
+    serv->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
+    serv->AddObserver(this, NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID, false);
+    serv->AddObserver(this, NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID, false);
+    serv->AddObserver(this, NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID, false);
+  }
+}
+
+nsCategoryObserver::~nsCategoryObserver()
+{
+}
+
+NS_IMPL_ISUPPORTS(nsCategoryObserver, nsIObserver)
+
+void
+nsCategoryObserver::ListenerDied()
+{
+  RemoveObservers();
+}
+
+void
+nsCategoryObserver::RemoveObservers()
+{
+  if (mObserversRemoved) {
+    return;
+  }
+
+  mObserversRemoved = true;
+  nsCOMPtr<nsIObserverService> obsSvc =
+    mozilla::services::GetObserverService();
+  if (obsSvc) {
+    obsSvc->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
+    obsSvc->RemoveObserver(this, NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID);
+    obsSvc->RemoveObserver(this, NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID);
+    obsSvc->RemoveObserver(this, NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID);
+  }
+}
+
+NS_IMETHODIMP
+nsCategoryObserver::Observe(nsISupports* aSubject, const char* aTopic,
+                            const char16_t* aData)
+{
+  if (strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
+    mHash.Clear();
+    RemoveObservers();
+
+    return NS_OK;
+  }
+
+  if (!aData ||
+      !nsDependentString(aData).Equals(NS_ConvertASCIItoUTF16(mCategory))) {
+    return NS_OK;
+  }
+
+  nsAutoCString str;
+  nsCOMPtr<nsISupportsCString> strWrapper(do_QueryInterface(aSubject));
+  if (strWrapper) {
+    strWrapper->GetData(str);
+  }
+
+  if (strcmp(aTopic, NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID) == 0) {
+    // We may get an add notification even when we already have an entry. This
+    // is due to the notification happening asynchronously, so if the entry gets
+    // added and an nsCategoryObserver gets instantiated before events get
+    // processed, we'd get the notification for an existing entry.
+    // Do nothing in that case.
+    if (mHash.GetWeak(str)) {
+      return NS_OK;
+    }
+
+    nsCOMPtr<nsICategoryManager> catMan =
+      do_GetService(NS_CATEGORYMANAGER_CONTRACTID);
+    if (!catMan) {
+      return NS_OK;
+    }
+
+    nsCString entryValue;
+    catMan->GetCategoryEntry(mCategory.get(),
+                             str.get(),
+                             getter_Copies(entryValue));
+
+    nsCOMPtr<nsISupports> service = do_GetService(entryValue.get());
+
+    if (service) {
+      mHash.Put(str, service);
+    }
+  } else if (strcmp(aTopic, NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID) == 0) {
+    mHash.Remove(str);
+  } else if (strcmp(aTopic, NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID) == 0) {
+    mHash.Clear();
+  }
+  return NS_OK;
+}
diff --git a/xpcom/glue/nsCategoryCache.h b/xpcom/glue/nsCategoryCache.h
new file mode 100644
index 0000000000..023aa7a75e
--- /dev/null
+++ b/xpcom/glue/nsCategoryCache.h
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCategoryCache_h_
+#define nsCategoryCache_h_
+
+#include "mozilla/Attributes.h"
+
+#include "nsICategoryManager.h"
+#include "nsIObserver.h"
+#include "nsISimpleEnumerator.h"
+#include "nsISupportsPrimitives.h"
+
+#include "nsServiceManagerUtils.h"
+
+#include "nsAutoPtr.h"
+#include "nsCOMArray.h"
+#include "nsInterfaceHashtable.h"
+
+#include "nsXPCOM.h"
+
+class nsCategoryObserver final : public nsIObserver
+{
+  ~nsCategoryObserver();
+
+public:
+  explicit nsCategoryObserver(const char* aCategory);
+
+  void ListenerDied();
+  nsInterfaceHashtable<nsCStringHashKey, nsISupports>& GetHash()
+  {
+    return mHash;
+  }
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+private:
+  void RemoveObservers();
+
+  nsInterfaceHashtable<nsCStringHashKey, nsISupports> mHash;
+  nsCString mCategory;
+  bool mObserversRemoved;
+};
+
+/**
+ * This is a helper class that caches services that are registered in a certain
+ * category. The intended usage is that a service stores a variable of type
+ * nsCategoryCache<nsIFoo> in a member variable, where nsIFoo is the interface
+ * that these services should implement. The constructor of this class should
+ * then get the name of the category.
+ */
+template<class T>
+class nsCategoryCache final
+{
+public:
+  explicit nsCategoryCache(const char* aCategory)
+    : mCategoryName(aCategory)
+  {
+  }
+  ~nsCategoryCache()
+  {
+    if (mObserver) {
+      mObserver->ListenerDied();
+    }
+  }
+
+  void GetEntries(nsCOMArray<T>& aResult)
+  {
+    // Lazy initialization, so that services in this category can't
+    // cause reentrant getService (bug 386376)
+    if (!mObserver) {
+      mObserver = new nsCategoryObserver(mCategoryName.get());
+    }
+
+    for (auto iter = mObserver->GetHash().Iter(); !iter.Done(); iter.Next()) {
+      nsISupports* entry = iter.UserData();
+      nsCOMPtr<T> service = do_QueryInterface(entry);
+      if (service) {
+        aResult.AppendElement(service.forget());
+      }
+    }
+  }
+
+private:
+  // Not to be implemented
+  nsCategoryCache(const nsCategoryCache<T>&);
+
+  nsCString mCategoryName;
+  RefPtr<nsCategoryObserver> mObserver;
+};
+
+#endif
diff --git a/xpcom/glue/nsClassHashtable.h b/xpcom/glue/nsClassHashtable.h
new file mode 100644
index 0000000000..53ca5676b8
--- /dev/null
+++ b/xpcom/glue/nsClassHashtable.h
@@ -0,0 +1,140 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsClassHashtable_h__
+#define nsClassHashtable_h__
+
+#include "mozilla/Move.h"
+#include "nsBaseHashtable.h"
+#include "nsHashKeys.h"
+#include "nsAutoPtr.h"
+
+/**
+ * templated hashtable class maps keys to C++ object pointers.
+ * See nsBaseHashtable for complete declaration.
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param Class the class-type being wrapped
+ * @see nsInterfaceHashtable, nsClassHashtable
+ */
+template<class KeyClass, class T>
+class nsClassHashtable
+  : public nsBaseHashtable<KeyClass, nsAutoPtr<T>, T*>
+{
+public:
+  typedef typename KeyClass::KeyType KeyType;
+  typedef T* UserDataType;
+  typedef nsBaseHashtable<KeyClass, nsAutoPtr<T>, T*> base_type;
+
+  using base_type::IsEmpty;
+
+  nsClassHashtable() {}
+  explicit nsClassHashtable(uint32_t aInitLength)
+    : nsBaseHashtable<KeyClass, nsAutoPtr<T>, T*>(aInitLength)
+  {
+  }
+
+  /**
+   * Looks up aKey in the hash table. If it doesn't exist a new object of
+   * KeyClass will be created (using the arguments provided) and then returned.
+   */
+  template<typename... Args>
+  UserDataType LookupOrAdd(KeyType aKey, Args&&... aConstructionArgs);
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   * @param aData if the key doesn't exist, pData will be set to nullptr.
+   */
+  bool Get(KeyType aKey, UserDataType* aData) const;
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   * @returns nullptr if the key is not present.
+   */
+  UserDataType Get(KeyType aKey) const;
+
+  /**
+   * Remove the entry for the given key from the hashtable and return it in
+   * aOut.  If the key is not in the hashtable, aOut's pointer is set to
+   * nullptr.
+   *
+   * Normally, an entry is deleted when it's removed from an nsClassHashtable,
+   * but this function transfers ownership of the entry back to the caller
+   * through aOut -- the entry will be deleted when aOut goes out of scope.
+   *
+   * @param aKey the key to get and remove from the hashtable
+   */
+  void RemoveAndForget(KeyType aKey, nsAutoPtr<T>& aOut);
+};
+
+//
+// nsClassHashtable definitions
+//
+
+template<class KeyClass, class T>
+template<typename... Args>
+T*
+nsClassHashtable<KeyClass, T>::LookupOrAdd(KeyType aKey,
+                                           Args&&... aConstructionArgs)
+{
+  typename base_type::EntryType* ent = this->PutEntry(aKey);
+  if (!ent->mData) {
+    ent->mData = new T(mozilla::Forward<Args>(aConstructionArgs)...);
+  }
+  return ent->mData;
+}
+
+template<class KeyClass, class T>
+bool
+nsClassHashtable<KeyClass, T>::Get(KeyType aKey, T** aRetVal) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aRetVal) {
+      *aRetVal = ent->mData;
+    }
+
+    return true;
+  }
+
+  if (aRetVal) {
+    *aRetVal = nullptr;
+  }
+
+  return false;
+}
+
+template<class KeyClass, class T>
+T*
+nsClassHashtable<KeyClass, T>::Get(KeyType aKey) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+  if (!ent) {
+    return nullptr;
+  }
+
+  return ent->mData;
+}
+
+template<class KeyClass, class T>
+void
+nsClassHashtable<KeyClass, T>::RemoveAndForget(KeyType aKey, nsAutoPtr<T>& aOut)
+{
+  aOut = nullptr;
+
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+  if (!ent) {
+    return;
+  }
+
+  // Transfer ownership from ent->mData into aOut.
+  aOut = mozilla::Move(ent->mData);
+
+  this->Remove(aKey);
+}
+
+#endif // nsClassHashtable_h__
diff --git a/xpcom/glue/nsClassInfoImpl.cpp b/xpcom/glue/nsClassInfoImpl.cpp
new file mode 100644
index 0000000000..6eb34f9f7c
--- /dev/null
+++ b/xpcom/glue/nsClassInfoImpl.cpp
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIClassInfoImpl.h"
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+GenericClassInfo::AddRef()
+{
+  return 2;
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+GenericClassInfo::Release()
+{
+  return 1;
+}
+
+NS_IMPL_QUERY_INTERFACE(GenericClassInfo, nsIClassInfo)
+
+NS_IMETHODIMP
+GenericClassInfo::GetInterfaces(uint32_t* aCount, nsIID*** aArray)
+{
+  return mData->getinterfaces(aCount, aArray);
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetScriptableHelper(nsIXPCScriptable** aHelper)
+{
+  if (mData->getscriptablehelper) {
+    return mData->getscriptablehelper(aHelper);
+  }
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetContractID(char** aContractID)
+{
+  NS_ERROR("GetContractID not implemented");
+  *aContractID = nullptr;
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetClassDescription(char** aDescription)
+{
+  *aDescription = nullptr;
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetClassID(nsCID** aClassID)
+{
+  NS_ERROR("GetClassID not implemented");
+  *aClassID = nullptr;
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetFlags(uint32_t* aFlags)
+{
+  *aFlags = mData->flags;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetClassIDNoAlloc(nsCID* aClassIDNoAlloc)
+{
+  *aClassIDNoAlloc = mData->cid;
+  return NS_OK;
+}
diff --git a/xpcom/glue/nsComponentManagerUtils.cpp b/xpcom/glue/nsComponentManagerUtils.cpp
new file mode 100644
index 0000000000..d8a590fa72
--- /dev/null
+++ b/xpcom/glue/nsComponentManagerUtils.cpp
@@ -0,0 +1,301 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPCOM_h__
+#include "nsXPCOM.h"
+#endif
+
+#ifndef nsCOMPtr_h__
+#include "nsCOMPtr.h"
+#endif
+
+#include "nsComponentManagerUtils.h"
+#include "nsServiceManagerUtils.h"
+
+#include "nsIComponentManager.h"
+
+#ifndef MOZILLA_INTERNAL_API
+
+nsresult
+CallGetService(const nsCID& aCID, const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIServiceManager> servMgr;
+  nsresult status = NS_GetServiceManager(getter_AddRefs(servMgr));
+  if (servMgr) {
+    status = servMgr->GetService(aCID, aIID, aResult);
+  }
+  return status;
+}
+
+nsresult
+CallGetService(const char* aContractID, const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIServiceManager> servMgr;
+  nsresult status = NS_GetServiceManager(getter_AddRefs(servMgr));
+  if (servMgr) {
+    status = servMgr->GetServiceByContractID(aContractID, aIID, aResult);
+  }
+  return status;
+}
+
+#else
+
+#include "nsComponentManager.h"
+
+nsresult
+CallGetService(const nsCID& aCID, const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return compMgr->nsComponentManagerImpl::GetService(aCID, aIID, aResult);
+}
+
+nsresult
+CallGetService(const char* aContractID, const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return compMgr->nsComponentManagerImpl::GetServiceByContractID(aContractID,
+                                                                 aIID,
+                                                                 aResult);
+}
+
+#endif
+
+#ifndef MOZILLA_INTERNAL_API
+
+nsresult
+CallCreateInstance(const nsCID& aCID, nsISupports* aDelegate,
+                   const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIComponentManager> compMgr;
+  nsresult status = NS_GetComponentManager(getter_AddRefs(compMgr));
+  if (compMgr) {
+    status = compMgr->CreateInstance(aCID, aDelegate, aIID, aResult);
+  }
+  return status;
+}
+
+nsresult
+CallCreateInstance(const char* aContractID, nsISupports* aDelegate,
+                   const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIComponentManager> compMgr;
+  nsresult status = NS_GetComponentManager(getter_AddRefs(compMgr));
+  if (compMgr)
+    status = compMgr->CreateInstanceByContractID(aContractID, aDelegate,
+                                                 aIID, aResult);
+  return status;
+}
+
+nsresult
+CallGetClassObject(const nsCID& aCID, const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIComponentManager> compMgr;
+  nsresult status = NS_GetComponentManager(getter_AddRefs(compMgr));
+  if (compMgr) {
+    status = compMgr->GetClassObject(aCID, aIID, aResult);
+  }
+  return status;
+}
+
+nsresult
+CallGetClassObject(const char* aContractID, const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIComponentManager> compMgr;
+  nsresult status = NS_GetComponentManager(getter_AddRefs(compMgr));
+  if (compMgr)
+    status = compMgr->GetClassObjectByContractID(aContractID, aIID,
+                                                 aResult);
+  return status;
+}
+
+#else
+
+#include "nsComponentManager.h"
+
+nsresult
+CallCreateInstance(const nsCID& aCID, nsISupports* aDelegate,
+                   const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return compMgr->nsComponentManagerImpl::CreateInstance(aCID, aDelegate, aIID,
+                                                         aResult);
+}
+
+nsresult
+CallCreateInstance(const char* aContractID, nsISupports* aDelegate,
+                   const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return
+    compMgr->nsComponentManagerImpl::CreateInstanceByContractID(aContractID,
+                                                                aDelegate, aIID,
+                                                                aResult);
+}
+
+nsresult
+CallGetClassObject(const nsCID& aCID, const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return compMgr->nsComponentManagerImpl::GetClassObject(aCID, aIID, aResult);
+}
+
+nsresult
+CallGetClassObject(const char* aContractID, const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return
+    compMgr->nsComponentManagerImpl::GetClassObjectByContractID(aContractID,
+                                                                aIID, aResult);
+}
+
+#endif
+
+nsresult
+nsCreateInstanceByCID::operator()(const nsIID& aIID, void** aInstancePtr) const
+{
+  nsresult status = CallCreateInstance(mCID, nullptr, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+nsresult
+nsCreateInstanceByContractID::operator()(const nsIID& aIID,
+                                         void** aInstancePtr) const
+{
+  nsresult status = CallCreateInstance(mContractID, nullptr, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+nsresult
+nsCreateInstanceFromFactory::operator()(const nsIID& aIID,
+                                        void** aInstancePtr) const
+{
+  nsresult status = mFactory->CreateInstance(nullptr, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+
+nsresult
+nsGetClassObjectByCID::operator()(const nsIID& aIID, void** aInstancePtr) const
+{
+  nsresult status = CallGetClassObject(mCID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+nsresult
+nsGetClassObjectByContractID::operator()(const nsIID& aIID,
+                                         void** aInstancePtr) const
+{
+  nsresult status = CallGetClassObject(mContractID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+
+nsresult
+nsGetServiceByCID::operator()(const nsIID& aIID, void** aInstancePtr) const
+{
+  nsresult status = CallGetService(mCID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+
+  return status;
+}
+
+nsresult
+nsGetServiceByCIDWithError::operator()(const nsIID& aIID,
+                                       void** aInstancePtr) const
+{
+  nsresult status = CallGetService(mCID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+nsresult
+nsGetServiceByContractID::operator()(const nsIID& aIID,
+                                     void** aInstancePtr) const
+{
+  nsresult status = CallGetService(mContractID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+
+  return status;
+}
+
+nsresult
+nsGetServiceByContractIDWithError::operator()(const nsIID& aIID,
+                                              void** aInstancePtr) const
+{
+  nsresult status = CallGetService(mContractID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
diff --git a/xpcom/glue/nsComponentManagerUtils.h b/xpcom/glue/nsComponentManagerUtils.h
new file mode 100644
index 0000000000..2a7a4fbd7c
--- /dev/null
+++ b/xpcom/glue/nsComponentManagerUtils.h
@@ -0,0 +1,247 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsComponentManagerUtils_h__
+#define nsComponentManagerUtils_h__
+
+#include "nscore.h"
+#include "nsCOMPtr.h"
+
+#include "nsIFactory.h"
+
+
+nsresult CallCreateInstance(const nsCID& aClass, nsISupports* aDelegate,
+                            const nsIID& aIID, void** aResult);
+
+nsresult CallCreateInstance(const char* aContractID, nsISupports* aDelegate,
+                            const nsIID& aIID, void** aResult);
+
+nsresult CallGetClassObject(const nsCID& aClass, const nsIID& aIID,
+                            void** aResult);
+
+nsresult CallGetClassObject(const char* aContractID, const nsIID& aIID,
+                            void** aResult);
+
+
+class MOZ_STACK_CLASS nsCreateInstanceByCID final : public nsCOMPtr_helper
+{
+public:
+  nsCreateInstanceByCID(const nsCID& aCID, nsresult* aErrorPtr)
+    : mCID(aCID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const
+    override;
+
+private:
+  const nsCID&    mCID;
+  nsresult*       mErrorPtr;
+};
+
+class MOZ_STACK_CLASS nsCreateInstanceByContractID final : public nsCOMPtr_helper
+{
+public:
+  nsCreateInstanceByContractID(const char* aContractID, nsresult* aErrorPtr)
+    : mContractID(aContractID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const override;
+
+private:
+  const char*   mContractID;
+  nsresult*     mErrorPtr;
+};
+
+class MOZ_STACK_CLASS nsCreateInstanceFromFactory final : public nsCOMPtr_helper
+{
+public:
+  nsCreateInstanceFromFactory(nsIFactory* aFactory, nsresult* aErrorPtr)
+    : mFactory(aFactory)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const override;
+
+private:
+  nsIFactory* MOZ_NON_OWNING_REF mFactory;
+  nsresult*     mErrorPtr;
+};
+
+
+inline const nsCreateInstanceByCID
+do_CreateInstance(const nsCID& aCID, nsresult* aError = 0)
+{
+  return nsCreateInstanceByCID(aCID, aError);
+}
+
+inline const nsCreateInstanceByContractID
+do_CreateInstance(const char* aContractID, nsresult* aError = 0)
+{
+  return nsCreateInstanceByContractID(aContractID, aError);
+}
+
+inline const nsCreateInstanceFromFactory
+do_CreateInstance(nsIFactory* aFactory, nsresult* aError = 0)
+{
+  return nsCreateInstanceFromFactory(aFactory, aError);
+}
+
+
+class MOZ_STACK_CLASS nsGetClassObjectByCID final : public nsCOMPtr_helper
+{
+public:
+  nsGetClassObjectByCID(const nsCID& aCID, nsresult* aErrorPtr)
+    : mCID(aCID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const override;
+
+private:
+  const nsCID&    mCID;
+  nsresult*       mErrorPtr;
+};
+
+class MOZ_STACK_CLASS nsGetClassObjectByContractID final : public nsCOMPtr_helper
+{
+public:
+  nsGetClassObjectByContractID(const char* aContractID, nsresult* aErrorPtr)
+    : mContractID(aContractID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const override;
+
+private:
+  const char*   mContractID;
+  nsresult*     mErrorPtr;
+};
+
+/**
+ * do_GetClassObject can be used to improve performance of callers
+ * that call |CreateInstance| many times.  They can cache the factory
+ * and call do_CreateInstance or CallCreateInstance with the cached
+ * factory rather than having the component manager retrieve it every
+ * time.
+ */
+inline const nsGetClassObjectByCID
+do_GetClassObject(const nsCID& aCID, nsresult* aError = 0)
+{
+  return nsGetClassObjectByCID(aCID, aError);
+}
+
+inline const nsGetClassObjectByContractID
+do_GetClassObject(const char* aContractID, nsresult* aError = 0)
+{
+  return nsGetClassObjectByContractID(aContractID, aError);
+}
+
+// type-safe shortcuts for calling |CreateInstance|
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(const nsCID& aClass,
+                   nsISupports* aDelegate,
+                   DestinationType** aDestination)
+{
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallCreateInstance(aClass, aDelegate,
+                            NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(const nsCID& aClass, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallCreateInstance(aClass, nullptr,
+                            NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(const char* aContractID,
+                   nsISupports* aDelegate,
+                   DestinationType** aDestination)
+{
+  NS_PRECONDITION(aContractID, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallCreateInstance(aContractID,
+                            aDelegate,
+                            NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(const char* aContractID, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aContractID, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallCreateInstance(aContractID, nullptr,
+                            NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(nsIFactory* aFactory,
+                   nsISupports* aDelegate,
+                   DestinationType** aDestination)
+{
+  NS_PRECONDITION(aFactory, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return aFactory->CreateInstance(aDelegate,
+                                  NS_GET_TEMPLATE_IID(DestinationType),
+                                  reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(nsIFactory* aFactory, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aFactory, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return aFactory->CreateInstance(nullptr,
+                                  NS_GET_TEMPLATE_IID(DestinationType),
+                                  reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallGetClassObject(const nsCID& aClass, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallGetClassObject(aClass, NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallGetClassObject(const char* aContractID, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallGetClassObject(aContractID, NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+#endif /* nsComponentManagerUtils_h__ */
diff --git a/xpcom/glue/nsCycleCollectionNoteChild.h b/xpcom/glue/nsCycleCollectionNoteChild.h
new file mode 100644
index 0000000000..5d47caefd0
--- /dev/null
+++ b/xpcom/glue/nsCycleCollectionNoteChild.h
@@ -0,0 +1,101 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This header will be included by headers that define refpointer and array classes
+// in order to specialize CC helpers such as ImplCycleCollectionTraverse for them.
+
+#ifndef nsCycleCollectionNoteChild_h__
+#define nsCycleCollectionNoteChild_h__
+
+#include "nsCycleCollectionTraversalCallback.h"
+#include "mozilla/Likely.h"
+#include "mozilla/TypeTraits.h"
+
+enum
+{
+  CycleCollectionEdgeNameArrayFlag = 1
+};
+
+// Just a helper for appending "[i]". Didn't want to pull in string headers here.
+void
+CycleCollectionNoteEdgeNameImpl(nsCycleCollectionTraversalCallback& aCallback,
+                                const char* aName,
+                                uint32_t aFlags = 0);
+
+// Should be inlined so that in the no-debug-info case this is just a simple if().
+MOZ_ALWAYS_INLINE void
+CycleCollectionNoteEdgeName(nsCycleCollectionTraversalCallback& aCallback,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  if (MOZ_UNLIKELY(aCallback.WantDebugInfo())) {
+    CycleCollectionNoteEdgeNameImpl(aCallback, aName, aFlags);
+  }
+}
+
+#define NS_CYCLE_COLLECTION_INNERCLASS                                         \
+        cycleCollection
+
+#define NS_CYCLE_COLLECTION_INNERNAME                                          \
+        _cycleCollectorGlobal
+
+#define NS_CYCLE_COLLECTION_PARTICIPANT(_class)                                \
+        _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()
+
+template<typename T>
+nsISupports*
+ToSupports(T* aPtr, typename T::NS_CYCLE_COLLECTION_INNERCLASS* aDummy = 0)
+{
+  return T::NS_CYCLE_COLLECTION_INNERCLASS::Upcast(aPtr);
+}
+
+// The default implementation of this class template is empty, because it
+// should never be used: see the partial specializations below.
+template<typename T,
+         bool IsXPCOM = mozilla::IsBaseOf<nsISupports, T>::value>
+struct CycleCollectionNoteChildImpl
+{
+};
+
+template<typename T>
+struct CycleCollectionNoteChildImpl<T, true>
+{
+  static void Run(nsCycleCollectionTraversalCallback& aCallback, T* aChild)
+  {
+    aCallback.NoteXPCOMChild(ToSupports(aChild));
+  }
+};
+
+template<typename T>
+struct CycleCollectionNoteChildImpl<T, false>
+{
+  static void Run(nsCycleCollectionTraversalCallback& aCallback, T* aChild)
+  {
+    aCallback.NoteNativeChild(aChild, NS_CYCLE_COLLECTION_PARTICIPANT(T));
+  }
+};
+
+// We declare CycleCollectionNoteChild in 3-argument and 4-argument variants,
+// rather than using default arguments, so that forward declarations work
+// regardless of header inclusion order.
+template<typename T>
+inline void
+CycleCollectionNoteChild(nsCycleCollectionTraversalCallback& aCallback,
+                         T* aChild, const char* aName, uint32_t aFlags)
+{
+  CycleCollectionNoteEdgeName(aCallback, aName, aFlags);
+  CycleCollectionNoteChildImpl<T>::Run(aCallback, aChild);
+}
+
+template<typename T>
+inline void
+CycleCollectionNoteChild(nsCycleCollectionTraversalCallback& aCallback,
+                         T* aChild, const char* aName)
+{
+  CycleCollectionNoteChild(aCallback, aChild, aName, 0);
+}
+
+#endif // nsCycleCollectionNoteChild_h__
diff --git a/xpcom/glue/nsCycleCollectionNoteRootCallback.h b/xpcom/glue/nsCycleCollectionNoteRootCallback.h
new file mode 100644
index 0000000000..42c43f301f
--- /dev/null
+++ b/xpcom/glue/nsCycleCollectionNoteRootCallback.h
@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCycleCollectionNoteRootCallback_h__
+#define nsCycleCollectionNoteRootCallback_h__
+
+class nsCycleCollectionParticipant;
+class nsISupports;
+
+class nsCycleCollectionNoteRootCallback
+{
+public:
+  NS_IMETHOD_(void) NoteXPCOMRoot(nsISupports* aRoot) = 0;
+  NS_IMETHOD_(void) NoteJSRoot(JSObject* aRoot) = 0;
+  NS_IMETHOD_(void) NoteNativeRoot(void* aRoot,
+                                   nsCycleCollectionParticipant* aParticipant) = 0;
+
+  NS_IMETHOD_(void) NoteWeakMapping(JSObject* aMap, JS::GCCellPtr aKey,
+                                    JSObject* aKeyDelegate, JS::GCCellPtr aVal) = 0;
+
+  bool WantAllTraces() const { return mWantAllTraces; }
+protected:
+  nsCycleCollectionNoteRootCallback() : mWantAllTraces(false) {}
+
+  bool mWantAllTraces;
+};
+
+#endif // nsCycleCollectionNoteRootCallback_h__
diff --git a/xpcom/glue/nsCycleCollectionParticipant.cpp b/xpcom/glue/nsCycleCollectionParticipant.cpp
new file mode 100644
index 0000000000..973ef2ff59
--- /dev/null
+++ b/xpcom/glue/nsCycleCollectionParticipant.cpp
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCycleCollectionParticipant.h"
+#include "nsCOMPtr.h"
+
+NS_IMETHODIMP_(void)
+nsXPCOMCycleCollectionParticipant::Root(void* aPtr)
+{
+  nsISupports* s = static_cast<nsISupports*>(aPtr);
+  NS_ADDREF(s);
+}
+
+NS_IMETHODIMP_(void)
+nsXPCOMCycleCollectionParticipant::Unroot(void* aPtr)
+{
+  nsISupports* s = static_cast<nsISupports*>(aPtr);
+  NS_RELEASE(s);
+}
+
+// We define a default trace function because some participants don't need
+// to trace anything, so it is okay for them not to define one.
+NS_IMETHODIMP_(void)
+nsXPCOMCycleCollectionParticipant::Trace(void* aPtr, const TraceCallbacks& aCb,
+                                         void* aClosure)
+{
+}
+
+bool
+nsXPCOMCycleCollectionParticipant::CheckForRightISupports(nsISupports* aSupports)
+{
+  nsISupports* foo;
+  aSupports->QueryInterface(NS_GET_IID(nsCycleCollectionISupports),
+                            reinterpret_cast<void**>(&foo));
+  return aSupports == foo;
+}
diff --git a/xpcom/glue/nsCycleCollectionParticipant.h b/xpcom/glue/nsCycleCollectionParticipant.h
new file mode 100644
index 0000000000..2dfbb6750e
--- /dev/null
+++ b/xpcom/glue/nsCycleCollectionParticipant.h
@@ -0,0 +1,852 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCycleCollectionParticipant_h__
+#define nsCycleCollectionParticipant_h__
+
+#include "mozilla/MacroArgs.h"
+#include "mozilla/MacroForEach.h"
+#include "nsCycleCollectionNoteChild.h"
+#include "js/RootingAPI.h"
+
+#define NS_XPCOMCYCLECOLLECTIONPARTICIPANT_IID                                 \
+{                                                                              \
+    0x9674489b,                                                                \
+    0x1f6f,                                                                    \
+    0x4550,                                                                    \
+    { 0xa7, 0x30, 0xcc, 0xae, 0xdd, 0x10, 0x4c, 0xf9 }                         \
+}
+
+/**
+ * Special IID to get at the base nsISupports for a class. Usually this is the
+ * canonical nsISupports pointer, but in the case of tearoffs for example it is
+ * the base nsISupports pointer of the tearoff. This allow the cycle collector
+ * to have separate nsCycleCollectionParticipant's for tearoffs or aggregated
+ * classes.
+ */
+#define NS_CYCLECOLLECTIONISUPPORTS_IID                                        \
+{                                                                              \
+    0xc61eac14,                                                                \
+    0x5f7a,                                                                    \
+    0x4481,                                                                    \
+    { 0x96, 0x5e, 0x7e, 0xaa, 0x6e, 0xff, 0xa8, 0x5f }                         \
+}
+
+/**
+ * Just holds the IID so NS_GET_IID works.
+ */
+class nsCycleCollectionISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_CYCLECOLLECTIONISUPPORTS_IID)
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsCycleCollectionISupports,
+                              NS_CYCLECOLLECTIONISUPPORTS_IID)
+
+namespace JS {
+template<class T> class Heap;
+} /* namespace JS */
+
+/*
+ * A struct defining pure virtual methods which are called when tracing cycle
+ * collection paticipants.  The appropriate method is called depending on the
+ * type of JS GC thing.
+ */
+struct TraceCallbacks
+{
+  virtual void Trace(JS::Heap<JS::Value>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::Heap<jsid>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::Heap<JSObject*>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JSObject** aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::TenuredHeap<JSObject*>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::Heap<JSString*>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::Heap<JSScript*>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::Heap<JSFunction*>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+};
+
+/*
+ * An implementation of TraceCallbacks that calls a single function for all JS
+ * GC thing types encountered. Implemented in nsCycleCollectorTraceJSHelpers.cpp.
+ */
+struct TraceCallbackFunc : public TraceCallbacks
+{
+  typedef void (*Func)(JS::GCCellPtr aPtr, const char* aName, void* aClosure);
+
+  explicit TraceCallbackFunc(Func aCb) : mCallback(aCb) {}
+
+  virtual void Trace(JS::Heap<JS::Value>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::Heap<jsid>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::Heap<JSObject*>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JSObject** aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::TenuredHeap<JSObject*>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::Heap<JSString*>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::Heap<JSScript*>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::Heap<JSFunction*>* aPtr, const char* aName,
+                     void* aClosure) const override;
+
+private:
+  Func mCallback;
+};
+
+/**
+ * Participant implementation classes
+ */
+class NS_NO_VTABLE nsCycleCollectionParticipant
+{
+public:
+  constexpr nsCycleCollectionParticipant() : mMightSkip(false) {}
+  constexpr explicit nsCycleCollectionParticipant(bool aSkip) : mMightSkip(aSkip) {}
+
+  NS_IMETHOD Traverse(void* aPtr, nsCycleCollectionTraversalCallback& aCb) = 0;
+
+  NS_IMETHOD_(void) Root(void* aPtr) = 0;
+  NS_IMETHOD_(void) Unlink(void* aPtr) = 0;
+  NS_IMETHOD_(void) Unroot(void* aPtr) = 0;
+  NS_IMETHOD_(const char*) ClassName() = 0;
+
+  NS_IMETHOD_(void) Trace(void* aPtr, const TraceCallbacks& aCb,
+                          void* aClosure) {}
+
+  // If CanSkip returns true, p is removed from the purple buffer during
+  // a call to nsCycleCollector_forgetSkippable().
+  // Note, calling CanSkip may remove objects from the purple buffer!
+  // If aRemovingAllowed is true, p can be removed from the purple buffer.
+  bool CanSkip(void* aPtr, bool aRemovingAllowed)
+  {
+    return mMightSkip ? CanSkipReal(aPtr, aRemovingAllowed) : false;
+  }
+
+  // If CanSkipInCC returns true, p is skipped when selecting roots for the
+  // cycle collector graph.
+  // Note, calling CanSkipInCC may remove other objects from the purple buffer!
+  bool CanSkipInCC(void* aPtr)
+  {
+    return mMightSkip ? CanSkipInCCReal(aPtr) : false;
+  }
+
+  // If CanSkipThis returns true, p is not added to the graph.
+  // This method is called during cycle collection, so don't
+  // change the state of any objects!
+  bool CanSkipThis(void* aPtr)
+  {
+    return mMightSkip ? CanSkipThisReal(aPtr) : false;
+  }
+
+  NS_IMETHOD_(void) DeleteCycleCollectable(void* aPtr) = 0;
+
+protected:
+  NS_IMETHOD_(bool) CanSkipReal(void* aPtr, bool aRemovingAllowed)
+  {
+    NS_ASSERTION(false, "Forgot to implement CanSkipReal?");
+    return false;
+  }
+  NS_IMETHOD_(bool) CanSkipInCCReal(void* aPtr)
+  {
+    NS_ASSERTION(false, "Forgot to implement CanSkipInCCReal?");
+    return false;
+  }
+  NS_IMETHOD_(bool) CanSkipThisReal(void* aPtr)
+  {
+    NS_ASSERTION(false, "Forgot to implement CanSkipThisReal?");
+    return false;
+  }
+
+private:
+  const bool mMightSkip;
+};
+
+class NS_NO_VTABLE nsScriptObjectTracer : public nsCycleCollectionParticipant
+{
+public:
+  constexpr nsScriptObjectTracer()
+    : nsCycleCollectionParticipant(false)
+  {
+  }
+  constexpr explicit nsScriptObjectTracer(bool aSkip)
+    : nsCycleCollectionParticipant(aSkip)
+  {
+  }
+
+  NS_IMETHOD_(void) Trace(void* aPtr, const TraceCallbacks& aCb,
+                          void* aClosure) override = 0;
+
+  // Implemented in nsCycleCollectorTraceJSHelpers.cpp.
+  static void NoteJSChild(JS::GCCellPtr aGCThing, const char* aName,
+                          void* aClosure);
+};
+
+class NS_NO_VTABLE nsXPCOMCycleCollectionParticipant : public nsScriptObjectTracer
+{
+public:
+  constexpr nsXPCOMCycleCollectionParticipant()
+    : nsScriptObjectTracer(false)
+  {
+  }
+  constexpr explicit nsXPCOMCycleCollectionParticipant(bool aSkip)
+    : nsScriptObjectTracer(aSkip)
+  {
+  }
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_XPCOMCYCLECOLLECTIONPARTICIPANT_IID)
+
+  NS_IMETHOD_(void) Root(void* aPtr) override;
+  NS_IMETHOD_(void) Unroot(void* aPtr) override;
+
+  NS_IMETHOD_(void) Trace(void* aPtr, const TraceCallbacks& aCb,
+                          void* aClosure) override;
+
+  static bool CheckForRightISupports(nsISupports* aSupports);
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsXPCOMCycleCollectionParticipant,
+                              NS_XPCOMCYCLECOLLECTIONPARTICIPANT_IID)
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing a QI to nsXPCOMCycleCollectionParticipant
+///////////////////////////////////////////////////////////////////////////////
+
+#define NS_CYCLE_COLLECTION_CLASSNAME(_class)                                  \
+        _class::NS_CYCLE_COLLECTION_INNERCLASS
+
+#define NS_IMPL_QUERY_CYCLE_COLLECTION(_class)                                 \
+  if ( aIID.Equals(NS_GET_IID(nsXPCOMCycleCollectionParticipant)) ) {          \
+    *aInstancePtr = NS_CYCLE_COLLECTION_PARTICIPANT(_class);                   \
+    return NS_OK;                                                              \
+  } else
+
+#define NS_IMPL_QUERY_CYCLE_COLLECTION_ISUPPORTS(_class)                       \
+  if ( aIID.Equals(NS_GET_IID(nsCycleCollectionISupports)) ) {                 \
+    *aInstancePtr = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this);       \
+    return NS_OK;                                                              \
+  } else
+
+#define NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION(_class)                        \
+  NS_IMPL_QUERY_CYCLE_COLLECTION(_class)
+
+#define NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_ISUPPORTS(_class)              \
+  NS_IMPL_QUERY_CYCLE_COLLECTION_ISUPPORTS(_class)
+
+#define NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(_class)                      \
+  NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION(_class)                              \
+  NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_ISUPPORTS(_class)
+
+#define NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(_class)                        \
+  NS_INTERFACE_MAP_BEGIN(_class)                                               \
+    NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(_class)
+
+#define NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(_class)              \
+  NS_INTERFACE_MAP_BEGIN(_class)                                               \
+    NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION(_class)
+
+#define NS_INTERFACE_TABLE_TO_MAP_SEGUE_CYCLE_COLLECTION(_class)  \
+  if (rv == NS_OK) return rv; \
+  nsISupports* foundInterface; \
+  NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(_class)
+
+#define NS_INTERFACE_TABLE_HEAD_CYCLE_COLLECTION_INHERITED(_class)            \
+  NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr)    \
+  {                                                                           \
+    NS_PRECONDITION(aInstancePtr, "null out param");                          \
+                                                                              \
+    if ( aIID.Equals(NS_GET_IID(nsXPCOMCycleCollectionParticipant)) ) {       \
+      *aInstancePtr = NS_CYCLE_COLLECTION_PARTICIPANT(_class);                \
+      return NS_OK;                                                           \
+    }                                                                         \
+    nsresult rv;
+
+#define NS_CYCLE_COLLECTION_UPCAST(obj, clazz)                                \
+  NS_CYCLE_COLLECTION_CLASSNAME(clazz)::Upcast(obj)
+
+#ifdef DEBUG
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT(_ptr) _ptr->CheckForRightParticipant()
+#else
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT(_ptr)
+#endif
+
+// The default implementation of this class template is empty, because it
+// should never be used: see the partial specializations below.
+template<typename T,
+         bool IsXPCOM = mozilla::IsBaseOf<nsISupports, T>::value>
+struct DowncastCCParticipantImpl
+{
+};
+
+// Specialization for XPCOM CC participants
+template<typename T>
+struct DowncastCCParticipantImpl<T, true>
+{
+  static T* Run(void* aPtr)
+  {
+    nsISupports* s = static_cast<nsISupports*>(aPtr);
+    MOZ_ASSERT(NS_CYCLE_COLLECTION_CLASSNAME(T)::CheckForRightISupports(s),
+               "not the nsISupports pointer we expect");
+    T* rval =  NS_CYCLE_COLLECTION_CLASSNAME(T)::Downcast(s);
+    NS_CHECK_FOR_RIGHT_PARTICIPANT(rval);
+    return rval;
+  }
+};
+
+// Specialization for native CC participants
+template<typename T>
+struct DowncastCCParticipantImpl<T, false>
+{
+  static T* Run(void* aPtr) { return static_cast<T*>(aPtr); }
+};
+
+template<typename T>
+T*
+DowncastCCParticipant(void* aPtr)
+{
+  return DowncastCCParticipantImpl<T>::Run(aPtr);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing CanSkip methods
+///////////////////////////////////////////////////////////////////////////////
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_BEGIN(_class)                        \
+  NS_IMETHODIMP_(bool)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::CanSkipReal(void *p,                  \
+                                                     bool aRemovingAllowed)    \
+  {                                                                            \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_END                                  \
+    (void)tmp;                                                                 \
+    return false;                                                              \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_IN_CC_BEGIN(_class)                  \
+  NS_IMETHODIMP_(bool)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::CanSkipInCCReal(void *p)              \
+  {                                                                            \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_IN_CC_END                            \
+    (void)tmp;                                                                 \
+    return false;                                                              \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_THIS_BEGIN(_class)                   \
+  NS_IMETHODIMP_(bool)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::CanSkipThisReal(void *p)              \
+  {                                                                            \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_THIS_END                             \
+    (void)tmp;                                                                 \
+    return false;                                                              \
+  }
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing nsCycleCollectionParticipant::Unlink
+//
+// You need to use NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED if you want
+// the base class Unlink version to be called before your own implementation.
+// You can use NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED if you want the
+// base class Unlink to get called after your own implementation.  You should
+// never use them together.
+///////////////////////////////////////////////////////////////////////////////
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                          \
+  NS_IMETHODIMP_(void)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Unlink(void *p)                       \
+  {                                                                            \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(_class, _base_class)   \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                \
+    nsISupports *s = static_cast<nsISupports*>(p);                             \
+    NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Unlink(s);
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_HELPER(_field)                        \
+  ImplCycleCollectionUnlink(tmp->_field);
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK(...)                                   \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                              \
+  MOZ_FOR_EACH(NS_IMPL_CYCLE_COLLECTION_UNLINK_HELPER, (), (__VA_ARGS__))
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                    \
+    (void)tmp;                                                                 \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED(_base_class)             \
+    nsISupports *s = static_cast<nsISupports*>(p);                             \
+    NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Unlink(s);                     \
+    (void)tmp;                                                                 \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_0(_class)                              \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing nsCycleCollectionParticipant::Traverse
+///////////////////////////////////////////////////////////////////////////////
+
+#define NS_IMPL_CYCLE_COLLECTION_DESCRIBE(_class, _refcnt)                     \
+    cb.DescribeRefCountedNode(_refcnt, #_class);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(_class)               \
+  NS_IMETHODIMP                                                                \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Traverse                              \
+                         (void *p, nsCycleCollectionTraversalCallback &cb)     \
+  {                                                                            \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class)                        \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(_class)                     \
+  NS_IMPL_CYCLE_COLLECTION_DESCRIBE(_class, tmp->mRefCnt.get())
+
+// Base class' CC participant should return NS_SUCCESS_INTERRUPTED_TRAVERSE
+// from Traverse if it wants derived classes to not traverse anything from
+// their CC participant.
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(_class, _base_class) \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(_class)                     \
+    nsISupports *s = static_cast<nsISupports*>(p);                             \
+    if (NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Traverse(s, cb)            \
+        == NS_SUCCESS_INTERRUPTED_TRAVERSE) {                                  \
+      return NS_SUCCESS_INTERRUPTED_TRAVERSE;                                  \
+    }
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_HELPER(_field)                       \
+  ImplCycleCollectionTraverse(cb, tmp->_field, #_field, 0);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE(...)                                 \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                              \
+  MOZ_FOR_EACH(NS_IMPL_CYCLE_COLLECTION_TRAVERSE_HELPER, (), (__VA_ARGS__))
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_RAWPTR(_field)                       \
+  CycleCollectionNoteChild(cb, tmp->_field, #_field);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS                       \
+  {                                                                            \
+  TraceCallbackFunc noteJsChild(&nsScriptObjectTracer::NoteJSChild);           \
+  Trace(p, noteJsChild, &cb);                                                  \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END                                  \
+    (void)tmp;                                                                 \
+    return NS_OK;                                                              \
+  }
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing nsScriptObjectTracer::Trace
+///////////////////////////////////////////////////////////////////////////////
+
+#define NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(_class)                                 \
+  void                                                                               \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Trace(void *p,                              \
+                                               const TraceCallbacks &aCallbacks,     \
+                                               void *aClosure)                       \
+  {                                                                                  \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(_class, _base_class)    \
+  NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(_class)                                 \
+    nsISupports *s = static_cast<nsISupports*>(p);                             \
+    NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Trace(s, aCallbacks, aClosure);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(_field)              \
+  aCallbacks.Trace(&tmp->_field, #_field, aClosure);
+
+// NB: The (void)tmp; hack in the TRACE_END macro exists to support
+// implementations that don't need to do anything in their Trace method.
+// Without this hack, some compilers warn about the unused tmp local.
+#define NS_IMPL_CYCLE_COLLECTION_TRACE_END                                     \
+      (void)tmp;                                                               \
+  }
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing a concrete nsCycleCollectionParticipant
+///////////////////////////////////////////////////////////////////////////////
+
+// If a class defines a participant, then QIing an instance of that class to
+// nsXPCOMCycleCollectionParticipant should produce that participant.
+#ifdef DEBUG
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_BASE                                    \
+    virtual void CheckForRightParticipant()
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_DERIVED                                 \
+    virtual void CheckForRightParticipant() override
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_BODY(_class)                            \
+    {                                                                          \
+      nsXPCOMCycleCollectionParticipant *p;                                    \
+      CallQueryInterface(this, &p);                                            \
+      MOZ_ASSERT(p == &NS_CYCLE_COLLECTION_INNERNAME,                          \
+                 #_class " should QI to its own CC participant");              \
+    }
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)                            \
+    NS_CHECK_FOR_RIGHT_PARTICIPANT_BASE                                        \
+    NS_CHECK_FOR_RIGHT_PARTICIPANT_BODY(_class)
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)                  \
+    NS_CHECK_FOR_RIGHT_PARTICIPANT_DERIVED                                     \
+    NS_CHECK_FOR_RIGHT_PARTICIPANT_BODY(_class)
+#else
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)
+#endif
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class) \
+  NS_IMETHOD_(const char*) ClassName() override { return #_class; };
+
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_BODY_NO_UNLINK(_class, _base)           \
+public:                                                                        \
+  NS_IMETHOD Traverse(void *p, nsCycleCollectionTraversalCallback &cb)         \
+    override;                                                                  \
+  NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class)                           \
+  NS_IMETHOD_(void) DeleteCycleCollectable(void *p) override                   \
+  {                                                                            \
+    DowncastCCParticipant<_class>(p)->DeleteCycleCollectable();                \
+  }                                                                            \
+  static _class* Downcast(nsISupports* s)                                      \
+  {                                                                            \
+    return static_cast<_class*>(static_cast<_base*>(s));                       \
+  }                                                                            \
+  static nsISupports* Upcast(_class *p)                                        \
+  {                                                                            \
+    return NS_ISUPPORTS_CAST(_base*, p);                                       \
+  }                                                                            \
+  template<typename T>                                                         \
+  friend nsISupports*                                                          \
+  ToSupports(T* p, NS_CYCLE_COLLECTION_INNERCLASS* dummy);
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base)                     \
+  NS_DECL_CYCLE_COLLECTION_CLASS_BODY_NO_UNLINK(_class, _base)                 \
+  NS_IMETHOD_(void) Unlink(void *p) override;
+
+#define NS_PARTICIPANT_AS(type, participant)                                   \
+  const_cast<type*>(reinterpret_cast<const type*>(participant))
+
+#define NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                 \
+  static constexpr nsXPCOMCycleCollectionParticipant* GetParticipant()         \
+  {                                                                            \
+    return &_class::NS_CYCLE_COLLECTION_INNERNAME;                             \
+  }
+
+/**
+ * We use this macro to force that classes that inherit from a ccable class and
+ * declare their own participant declare themselves as inherited cc classes.
+ * To avoid possibly unnecessary vtables we only do this checking in debug
+ * builds.
+ */
+#ifdef DEBUG
+#define NOT_INHERITED_CANT_OVERRIDE virtual void BaseCycleCollectable() final {}
+#else
+#define NOT_INHERITED_CANT_OVERRIDE
+#endif
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(_class, _base)                \
+class NS_CYCLE_COLLECTION_INNERCLASS                                           \
+ : public nsXPCOMCycleCollectionParticipant                                    \
+{                                                                              \
+  NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base)                           \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                       \
+};                                                                             \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)                                    \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;           \
+  NOT_INHERITED_CANT_OVERRIDE
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS(_class)                                 \
+  NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(_class, _class)
+
+// Cycle collector helper for ambiguous classes that can sometimes be skipped.
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS_AMBIGUOUS(_class, _base)        \
+class NS_CYCLE_COLLECTION_INNERCLASS                                             \
+ : public nsXPCOMCycleCollectionParticipant                                      \
+{                                                                                \
+public:                                                                          \
+  constexpr NS_CYCLE_COLLECTION_INNERCLASS ()                                    \
+  : nsXPCOMCycleCollectionParticipant(true) {}                                   \
+private:                                                                         \
+  NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base)                             \
+  NS_IMETHOD_(bool) CanSkipReal(void *p, bool aRemovingAllowed) override;        \
+  NS_IMETHOD_(bool) CanSkipInCCReal(void *p) override;                           \
+  NS_IMETHOD_(bool) CanSkipThisReal(void *p) override;                           \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                         \
+};                                                                               \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)                                      \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;             \
+NOT_INHERITED_CANT_OVERRIDE
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS(_class)                       \
+        NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS_AMBIGUOUS(_class, _class)
+
+#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(_class, _base)          \
+class NS_CYCLE_COLLECTION_INNERCLASS                                                   \
+ : public nsXPCOMCycleCollectionParticipant                                            \
+{                                                                                      \
+  NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base)                                   \
+  NS_IMETHOD_(void) Trace(void *p, const TraceCallbacks &cb, void *closure) override;  \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                               \
+};                                                                                     \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)                                            \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME; \
+NOT_INHERITED_CANT_OVERRIDE
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_AMBIGUOUS(_class, _base)   \
+class NS_CYCLE_COLLECTION_INNERCLASS                                                      \
+ : public nsXPCOMCycleCollectionParticipant                                               \
+{                                                                                         \
+public:                                                                                   \
+  constexpr NS_CYCLE_COLLECTION_INNERCLASS ()                                             \
+  : nsXPCOMCycleCollectionParticipant(true) {}                                            \
+private:                                                                                  \
+  NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base)                                      \
+  NS_IMETHOD_(void) Trace(void *p, const TraceCallbacks &cb, void *closure) override;     \
+  NS_IMETHOD_(bool) CanSkipReal(void *p, bool aRemovingAllowed) override;                 \
+  NS_IMETHOD_(bool) CanSkipInCCReal(void *p) override;                                    \
+  NS_IMETHOD_(bool) CanSkipThisReal(void *p) override;                                    \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                                  \
+};                                                                                        \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)                                               \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME; \
+NOT_INHERITED_CANT_OVERRIDE
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS(_class)  \
+  NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_AMBIGUOUS(_class, _class)
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_INHERITED(_class,       \
+                                                                         _base_class)  \
+class NS_CYCLE_COLLECTION_INNERCLASS                                                   \
+ : public NS_CYCLE_COLLECTION_CLASSNAME(_base_class)                                   \
+{                                                                                      \
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class)                   \
+  NS_IMETHOD_(void) Trace(void *p, const TraceCallbacks &cb, void *closure) override;  \
+  NS_IMETHOD_(bool) CanSkipReal(void *p, bool aRemovingAllowed) override;              \
+  NS_IMETHOD_(bool) CanSkipInCCReal(void *p) override;                                 \
+  NS_IMETHOD_(bool) CanSkipThisReal(void *p) override;                                 \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                               \
+}; \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)  \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(_class)  \
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(_class, _class)
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY_NO_UNLINK(_class,        \
+                                                                _base_class)   \
+public:                                                                        \
+  NS_IMETHOD Traverse(void *p, nsCycleCollectionTraversalCallback &cb)         \
+    override;                                                                  \
+  NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class)                           \
+  static _class* Downcast(nsISupports* s)                                      \
+  {                                                                            \
+    return static_cast<_class*>(static_cast<_base_class*>(                     \
+      NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Downcast(s)));               \
+  }
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class)     \
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY_NO_UNLINK(_class, _base_class) \
+  NS_IMETHOD_(void) Unlink(void *p) override;
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(_class, _base_class)          \
+class NS_CYCLE_COLLECTION_INNERCLASS                                           \
+ : public NS_CYCLE_COLLECTION_CLASSNAME(_base_class)                           \
+{                                                                              \
+public:                                                                        \
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class)           \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                       \
+};                                                                             \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)                          \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_NO_UNLINK(_class,             \
+                                                           _base_class)        \
+class NS_CYCLE_COLLECTION_INNERCLASS                                           \
+ : public NS_CYCLE_COLLECTION_CLASSNAME(_base_class)                           \
+{                                                                              \
+public:                                                                        \
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY_NO_UNLINK(_class, _base_class) \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                       \
+};                                                                             \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)                          \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(_class,                 \
+                                                               _base_class)            \
+class NS_CYCLE_COLLECTION_INNERCLASS                                                   \
+ : public NS_CYCLE_COLLECTION_CLASSNAME(_base_class)                                   \
+{                                                                                      \
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class)                   \
+  NS_IMETHOD_(void) Trace(void *p, const TraceCallbacks &cb, void *closure)            \
+    override;                                                                          \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                               \
+};                                                                                     \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)                                  \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+// Cycle collector participant declarations.
+
+#define NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class)                     \
+  public:                                                                      \
+    NS_IMETHOD_(void) Root(void *n) override;                                  \
+    NS_IMETHOD_(void) Unlink(void *n) override;                                \
+    NS_IMETHOD_(void) Unroot(void *n) override;                                \
+    NS_IMETHOD Traverse(void *n, nsCycleCollectionTraversalCallback &cb)       \
+      override;                                                                \
+    NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class)                         \
+    NS_IMETHOD_(void) DeleteCycleCollectable(void *n) override                 \
+    {                                                                          \
+      DowncastCCParticipant<_class>(n)->DeleteCycleCollectable();              \
+    }                                                                          \
+    static _class* Downcast(void* s)                                           \
+    {                                                                          \
+      return DowncastCCParticipant<_class>(s);                                 \
+    }                                                                          \
+    static void* Upcast(_class *p)                                             \
+    {                                                                          \
+      return static_cast<void*>(p);                                            \
+    }
+
+#define NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(_class)                          \
+  void DeleteCycleCollectable(void)                                            \
+  {                                                                            \
+    delete this;                                                               \
+  }                                                                            \
+  class NS_CYCLE_COLLECTION_INNERCLASS                                         \
+   : public nsCycleCollectionParticipant                                       \
+  {                                                                            \
+    NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class)                         \
+    static constexpr nsCycleCollectionParticipant* GetParticipant()            \
+    {                                                                          \
+      return &_class::NS_CYCLE_COLLECTION_INNERNAME;                           \
+    }                                                                          \
+  };                                                                           \
+  static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_NATIVE_CLASS(_class)                \
+  void DeleteCycleCollectable(void)                                            \
+  {                                                                            \
+    delete this;                                                               \
+  }                                                                            \
+  class NS_CYCLE_COLLECTION_INNERCLASS                                         \
+   : public nsCycleCollectionParticipant                                       \
+  {                                                                            \
+  public:                                                                      \
+    constexpr NS_CYCLE_COLLECTION_INNERCLASS ()                                \
+    : nsCycleCollectionParticipant(true) {}                                    \
+  private:                                                                     \
+    NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class)                         \
+    NS_IMETHOD_(bool) CanSkipReal(void *p, bool aRemovingAllowed) override;    \
+    NS_IMETHOD_(bool) CanSkipInCCReal(void *p) override;                       \
+    NS_IMETHOD_(bool) CanSkipThisReal(void *p) override;                       \
+    static nsCycleCollectionParticipant* GetParticipant()                      \
+    {                                                                          \
+      return &_class::NS_CYCLE_COLLECTION_INNERNAME;                           \
+    }                                                                          \
+  };                                                                           \
+  static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_NATIVE_CLASS_WITH_CUSTOM_DELETE(_class) \
+class NS_CYCLE_COLLECTION_INNERCLASS                                           \
+ : public nsCycleCollectionParticipant                                         \
+{                                                                              \
+public:                                                                        \
+  constexpr NS_CYCLE_COLLECTION_INNERCLASS ()                                  \
+  : nsCycleCollectionParticipant(true) {}                                      \
+private:                                                                       \
+  NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class)                           \
+  NS_IMETHOD_(bool) CanSkipReal(void *p, bool aRemovingAllowed) override;      \
+  NS_IMETHOD_(bool) CanSkipInCCReal(void *p) override;                         \
+  NS_IMETHOD_(bool) CanSkipThisReal(void *p) override;                         \
+  static nsCycleCollectionParticipant* GetParticipant()                        \
+  {                                                                            \
+    return &_class::NS_CYCLE_COLLECTION_INNERNAME;                             \
+  }                                                                            \
+};                                                                             \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(_class)            \
+  void DeleteCycleCollectable(void)                                            \
+  {                                                                            \
+    delete this;                                                               \
+  }                                                                            \
+  class NS_CYCLE_COLLECTION_INNERCLASS                                         \
+   : public nsScriptObjectTracer                                               \
+  {                                                                            \
+    NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class)                         \
+    NS_IMETHOD_(void) Trace(void *p, const TraceCallbacks &cb, void *closure)  \
+      override;                                                                \
+    static constexpr nsScriptObjectTracer* GetParticipant()                    \
+    {                                                                          \
+      return &_class::NS_CYCLE_COLLECTION_INNERNAME;                           \
+    }                                                                          \
+  };                                                                           \
+  static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(_class, _root_function)           \
+  NS_IMETHODIMP_(void)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Root(void *p)                         \
+  {                                                                            \
+    _class *tmp = static_cast<_class*>(p);                                     \
+    tmp->_root_function();                                                     \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(_class, _unroot_function)       \
+  NS_IMETHODIMP_(void)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Unroot(void *p)                       \
+  {                                                                            \
+    _class *tmp = static_cast<_class*>(p);                                     \
+    tmp->_unroot_function();                                                   \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_CLASS(_class) \
+ _class::NS_CYCLE_COLLECTION_INNERCLASS _class::NS_CYCLE_COLLECTION_INNERNAME;
+
+// NB: This is not something you usually want to use.  It is here to allow
+// adding things to the CC graph to help debugging via CC logs, but it does not
+// traverse or unlink anything, so it is useless for anything else.
+#define NS_IMPL_CYCLE_COLLECTION_0(_class)                                     \
+  NS_IMPL_CYCLE_COLLECTION_CLASS(_class)                                       \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                          \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class)                              \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+#define NS_IMPL_CYCLE_COLLECTION(_class, ...)                                  \
+  NS_IMPL_CYCLE_COLLECTION_CLASS(_class)                                       \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(__VA_ARGS__)                                 \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                          \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class)                              \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(__VA_ARGS__)                               \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+// If you are looking for NS_IMPL_CYCLE_COLLECTION_INHERITED_0(_class, _base)
+// you should instead not declare any cycle collected stuff in _class, so it
+// will just inherit the CC declarations from _base.
+
+#define NS_IMPL_CYCLE_COLLECTION_INHERITED(_class, _base, ...)                 \
+  NS_IMPL_CYCLE_COLLECTION_CLASS(_class)                                       \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(_class, _base)               \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(__VA_ARGS__)                                 \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                          \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(_class, _base)             \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(__VA_ARGS__)                               \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+#define NS_CYCLE_COLLECTION_NOTE_EDGE_NAME CycleCollectionNoteEdgeName
+
+#endif // nsCycleCollectionParticipant_h__
diff --git a/xpcom/glue/nsCycleCollectionTraversalCallback.h b/xpcom/glue/nsCycleCollectionTraversalCallback.h
new file mode 100644
index 0000000000..9e314af9b2
--- /dev/null
+++ b/xpcom/glue/nsCycleCollectionTraversalCallback.h
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCycleCollectionTraversalCallback_h__
+#define nsCycleCollectionTraversalCallback_h__
+
+#include "jspubtd.h"
+#include "js/HeapAPI.h"
+#include "nsISupports.h"
+
+class nsCycleCollectionParticipant;
+
+class NS_NO_VTABLE nsCycleCollectionTraversalCallback
+{
+public:
+  // You must call DescribeRefCountedNode() with an accurate
+  // refcount, otherwise cycle collection will fail, and probably crash.
+  // If the callback cares about objname, it should put
+  // WANT_DEBUG_INFO in mFlags.
+  NS_IMETHOD_(void) DescribeRefCountedNode(nsrefcnt aRefcount,
+                                           const char* aObjName) = 0;
+  // Note, aCompartmentAddress is 0 if it is unknown.
+  NS_IMETHOD_(void) DescribeGCedNode(bool aIsMarked,
+                                     const char* aObjName,
+                                     uint64_t aCompartmentAddress = 0) = 0;
+
+  NS_IMETHOD_(void) NoteXPCOMChild(nsISupports* aChild) = 0;
+  NS_IMETHOD_(void) NoteJSChild(const JS::GCCellPtr& aThing) = 0;
+  NS_IMETHOD_(void) NoteNativeChild(void* aChild,
+                                    nsCycleCollectionParticipant* aHelper) = 0;
+
+  // Give a name to the edge associated with the next call to
+  // NoteXPCOMChild, NoteJSObject, NoteJSScript, or NoteNativeChild.
+  // Callbacks who care about this should set WANT_DEBUG_INFO in the
+  // flags.
+  NS_IMETHOD_(void) NoteNextEdgeName(const char* aName) = 0;
+
+  enum
+  {
+    // Values for flags:
+
+    // Caller should call NoteNextEdgeName and pass useful objName
+    // to DescribeRefCountedNode and DescribeGCedNode.
+    WANT_DEBUG_INFO = (1 << 0),
+
+    // Caller should not skip objects that we know will be
+    // uncollectable.
+    WANT_ALL_TRACES = (1 << 1)
+  };
+  uint32_t Flags() const { return mFlags; }
+  bool WantDebugInfo() const { return (mFlags & WANT_DEBUG_INFO) != 0; }
+  bool WantAllTraces() const { return (mFlags & WANT_ALL_TRACES) != 0; }
+protected:
+  nsCycleCollectionTraversalCallback() : mFlags(0) {}
+
+  uint32_t mFlags;
+};
+
+#endif // nsCycleCollectionTraversalCallback_h__
diff --git a/xpcom/glue/nsDataHashtable.h b/xpcom/glue/nsDataHashtable.h
new file mode 100644
index 0000000000..19c0728b4a
--- /dev/null
+++ b/xpcom/glue/nsDataHashtable.h
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDataHashtable_h__
+#define nsDataHashtable_h__
+
+#include "nsHashKeys.h"
+#include "nsBaseHashtable.h"
+#include "mozilla/Maybe.h"
+
+/**
+ * templated hashtable class maps keys to simple datatypes.
+ * See nsBaseHashtable for complete declaration
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param DataType the simple datatype being wrapped
+ * @see nsInterfaceHashtable, nsClassHashtable
+ */
+template<class KeyClass, class DataType>
+class nsDataHashtable
+  : public nsBaseHashtable<KeyClass, DataType, DataType>
+{
+private:
+  typedef nsBaseHashtable<KeyClass, DataType, DataType> BaseClass;
+
+public:
+  using typename BaseClass::KeyType;
+  using typename BaseClass::EntryType;
+
+  nsDataHashtable() {}
+  explicit nsDataHashtable(uint32_t aInitLength)
+    : BaseClass(aInitLength)
+  {
+  }
+
+  /**
+   * Retrieve the value for a key and remove the corresponding entry at
+   * the same time.
+   *
+   * @param aKey the key to retrieve and remove
+   * @return the found value, or Nothing if no entry was found with the
+   *   given key.
+   */
+  mozilla::Maybe<DataType> GetAndRemove(KeyType aKey)
+  {
+    mozilla::Maybe<DataType> value;
+    if (EntryType* ent = this->GetEntry(aKey)) {
+      value.emplace(mozilla::Move(ent->mData));
+      this->RemoveEntry(ent);
+    }
+    return value;
+  }
+};
+
+#endif // nsDataHashtable_h__
diff --git a/xpcom/glue/nsDebug.h b/xpcom/glue/nsDebug.h
new file mode 100644
index 0000000000..7365f9ce34
--- /dev/null
+++ b/xpcom/glue/nsDebug.h
@@ -0,0 +1,460 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDebug_h___
+#define nsDebug_h___
+
+#include "nscore.h"
+#include "nsError.h"
+
+#include "nsXPCOM.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Likely.h"
+#include <stdarg.h>
+
+#ifdef DEBUG
+#include "prprf.h"
+#endif
+
+/**
+ * Warn if the given condition is true. The condition is evaluated in both
+ * release and debug builds, and the result is an expression which can be
+ * used in subsequent expressions, such as:
+ *
+ * if (NS_WARN_IF(NS_FAILED(rv)) {
+ *   return rv;
+ * }
+ *
+ * This explicit warning and return is preferred to the NS_ENSURE_* macros
+ * which hide the warning and the return control flow.
+ *
+ * This macro can also be used outside of conditions just to issue a warning,
+ * like so:
+ *
+ *   Unused << NS_WARN_IF(NS_FAILED(FnWithSideEffects());
+ *
+ * (The |Unused <<| is necessary because of the MOZ_MUST_USE annotation.)
+ *
+ * However, note that the argument to this macro is evaluated in all builds. If
+ * you just want a warning assertion, it is better to use NS_WARNING_ASSERTION
+ * (which evaluates the condition only in debug builds) like so:
+ *
+ *   NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "operation failed");
+ *
+ * @note This is C++-only
+ */
+#ifdef __cplusplus
+#ifdef DEBUG
+inline MOZ_MUST_USE bool NS_warn_if_impl(bool aCondition, const char* aExpr,
+                                         const char* aFile, int32_t aLine)
+{
+  if (MOZ_UNLIKELY(aCondition)) {
+    NS_DebugBreak(NS_DEBUG_WARNING, nullptr, aExpr, aFile, aLine);
+  }
+  return aCondition;
+}
+#define NS_WARN_IF(condition) \
+  NS_warn_if_impl(condition, #condition, __FILE__, __LINE__)
+#else
+#define NS_WARN_IF(condition) (bool)(condition)
+#endif
+#endif
+
+/**
+ * Test an assertion for truth. If the expression is not true then
+ * emit a warning.
+ *
+ * Program execution continues past the usage of this macro.
+ *
+ * Note also that the non-debug version of this macro does <b>not</b>
+ * evaluate the message argument.
+ */
+#ifdef DEBUG
+#define NS_WARNING_ASSERTION(_expr, _msg)                     \
+  do {                                                        \
+    if (!(_expr)) {                                           \
+      NS_DebugBreak(NS_DEBUG_WARNING, _msg, #_expr, __FILE__, __LINE__); \
+    }                                                         \
+  } while(0)
+#else
+#define NS_WARNING_ASSERTION(_expr, _msg)  do { /* nothing */ } while(0)
+#endif
+
+/**
+ * Test an assertion for truth. If the expression is not true then
+ * trigger a program failure.
+ *
+ * Note that the non-debug version of this macro does <b>not</b>
+ * evaluate the message argument.
+ */
+#ifdef DEBUG
+inline void MOZ_PretendNoReturn()
+  MOZ_PRETEND_NORETURN_FOR_STATIC_ANALYSIS {}
+#define NS_ASSERTION(expr, str)                               \
+  do {                                                        \
+    if (!(expr)) {                                            \
+      NS_DebugBreak(NS_DEBUG_ASSERTION, str, #expr, __FILE__, __LINE__); \
+      MOZ_PretendNoReturn();                                         \
+    }                                                         \
+  } while(0)
+#else
+#define NS_ASSERTION(expr, str)        do { /* nothing */ } while(0)
+#endif
+
+/**
+ * NS_PRECONDITION/POSTCONDITION are synonyms for NS_ASSERTION.
+ */
+#define NS_PRECONDITION(expr, str) NS_ASSERTION(expr, str)
+#define NS_POSTCONDITION(expr, str) NS_ASSERTION(expr, str)
+
+/**
+ * This macros triggers a program failure if executed. It indicates that
+ * an attempt was made to execute some unimplemented functionality.
+ */
+#ifdef DEBUG
+#define NS_NOTYETIMPLEMENTED(str)                             \
+  do {                                                        \
+    NS_DebugBreak(NS_DEBUG_ASSERTION, str, "NotYetImplemented", __FILE__, __LINE__); \
+    MOZ_PretendNoReturn();                                    \
+  } while(0)
+#else
+#define NS_NOTYETIMPLEMENTED(str)      do { /* nothing */ } while(0)
+#endif
+
+/**
+ * This macros triggers a program failure if executed. It indicates that
+ * an attempt was made to execute a codepath which should not be reachable.
+ */
+#ifdef DEBUG
+#define NS_NOTREACHED(str)                                    \
+  do {                                                        \
+    NS_DebugBreak(NS_DEBUG_ASSERTION, str, "Not Reached", __FILE__, __LINE__); \
+    MOZ_PretendNoReturn();                                    \
+  } while(0)
+#else
+#define NS_NOTREACHED(str)             do { /* nothing */ } while(0)
+#endif
+
+/**
+ * Log an error message.
+ */
+#ifdef DEBUG
+#define NS_ERROR(str)                                         \
+  do {                                                        \
+    NS_DebugBreak(NS_DEBUG_ASSERTION, str, "Error", __FILE__, __LINE__); \
+    MOZ_PretendNoReturn();                                    \
+  } while(0)
+#else
+#define NS_ERROR(str)                  do { /* nothing */ } while(0)
+#endif
+
+/**
+ * Log a warning message.
+ */
+#ifdef DEBUG
+#define NS_WARNING(str)                                       \
+  NS_DebugBreak(NS_DEBUG_WARNING, str, nullptr, __FILE__, __LINE__)
+#else
+#define NS_WARNING(str)                do { /* nothing */ } while(0)
+#endif
+
+/**
+ * Trigger an debug-only abort.
+ *
+ * @see NS_RUNTIMEABORT for release-mode asserts.
+ */
+#ifdef DEBUG
+#define NS_ABORT()                                            \
+  do {                                                        \
+    NS_DebugBreak(NS_DEBUG_ABORT, nullptr, nullptr, __FILE__, __LINE__); \
+    MOZ_PretendNoReturn();                                    \
+  } while(0)
+#else
+#define NS_ABORT()                     do { /* nothing */ } while(0)
+#endif
+
+/**
+ * Trigger a debugger breakpoint, only in debug builds.
+ */
+#ifdef DEBUG
+#define NS_BREAK()                                            \
+  do {                                                        \
+    NS_DebugBreak(NS_DEBUG_BREAK, nullptr, nullptr, __FILE__, __LINE__); \
+    MOZ_PretendNoReturn();                                    \
+  } while(0)
+#else
+#define NS_BREAK()                     do { /* nothing */ } while(0)
+#endif
+
+/******************************************************************************
+** Macros for static assertions.  These are used by the sixgill tool.
+** When the tool is not running these macros are no-ops.
+******************************************************************************/
+
+/* Avoid name collision if included with other headers defining annotations. */
+#ifndef HAVE_STATIC_ANNOTATIONS
+#define HAVE_STATIC_ANNOTATIONS
+
+#ifdef XGILL_PLUGIN
+
+#define STATIC_PRECONDITION(COND)         __attribute__((precondition(#COND)))
+#define STATIC_PRECONDITION_ASSUME(COND)  __attribute__((precondition_assume(#COND)))
+#define STATIC_POSTCONDITION(COND)        __attribute__((postcondition(#COND)))
+#define STATIC_POSTCONDITION_ASSUME(COND) __attribute__((postcondition_assume(#COND)))
+#define STATIC_INVARIANT(COND)            __attribute__((invariant(#COND)))
+#define STATIC_INVARIANT_ASSUME(COND)     __attribute__((invariant_assume(#COND)))
+
+/* Used to make identifiers for assert/assume annotations in a function. */
+#define STATIC_PASTE2(X,Y) X ## Y
+#define STATIC_PASTE1(X,Y) STATIC_PASTE2(X,Y)
+
+#define STATIC_ASSUME(COND)                          \
+  do {                                               \
+    __attribute__((assume_static(#COND), unused))    \
+    int STATIC_PASTE1(assume_static_, __COUNTER__);  \
+  } while(0)
+
+#define STATIC_ASSERT_RUNTIME(COND)                         \
+  do {                                                      \
+    __attribute__((assert_static_runtime(#COND), unused))   \
+    int STATIC_PASTE1(assert_static_runtime_, __COUNTER__); \
+  } while(0)
+
+#else /* XGILL_PLUGIN */
+
+#define STATIC_PRECONDITION(COND)          /* nothing */
+#define STATIC_PRECONDITION_ASSUME(COND)   /* nothing */
+#define STATIC_POSTCONDITION(COND)         /* nothing */
+#define STATIC_POSTCONDITION_ASSUME(COND)  /* nothing */
+#define STATIC_INVARIANT(COND)             /* nothing */
+#define STATIC_INVARIANT_ASSUME(COND)      /* nothing */
+
+#define STATIC_ASSUME(COND)          do { /* nothing */ } while(0)
+#define STATIC_ASSERT_RUNTIME(COND)  do { /* nothing */ } while(0)
+
+#endif /* XGILL_PLUGIN */
+
+#define STATIC_SKIP_INFERENCE STATIC_INVARIANT(skip_inference())
+
+#endif /* HAVE_STATIC_ANNOTATIONS */
+
+/******************************************************************************
+** Macros for terminating execution when an unrecoverable condition is
+** reached.  These need to be compiled regardless of the DEBUG flag.
+******************************************************************************/
+
+/**
+ * Terminate execution <i>immediately</i>, and if possible on the current
+ * platform, in such a way that execution can't be continued by other
+ * code (e.g., by intercepting a signal).
+ */
+#define NS_RUNTIMEABORT(msg)                                    \
+  NS_DebugBreak(NS_DEBUG_ABORT, msg, nullptr, __FILE__, __LINE__)
+
+
+/* Macros for checking the trueness of an expression passed in within an
+ * interface implementation.  These need to be compiled regardless of the
+ * DEBUG flag. New code should use NS_WARN_IF(condition) instead!
+ * @status deprecated
+ */
+
+#define NS_ENSURE_TRUE(x, ret)                                \
+  do {                                                        \
+    if (MOZ_UNLIKELY(!(x))) {                                 \
+       NS_WARNING("NS_ENSURE_TRUE(" #x ") failed");           \
+       return ret;                                            \
+    }                                                         \
+  } while(0)
+
+#define NS_ENSURE_FALSE(x, ret)                               \
+  NS_ENSURE_TRUE(!(x), ret)
+
+#define NS_ENSURE_TRUE_VOID(x)                                \
+  do {                                                        \
+    if (MOZ_UNLIKELY(!(x))) {                                 \
+       NS_WARNING("NS_ENSURE_TRUE(" #x ") failed");           \
+       return;                                                \
+    }                                                         \
+  } while(0)
+
+#define NS_ENSURE_FALSE_VOID(x)                               \
+  NS_ENSURE_TRUE_VOID(!(x))
+
+/******************************************************************************
+** Macros for checking results
+******************************************************************************/
+
+#if defined(DEBUG) && !defined(XPCOM_GLUE_AVOID_NSPR)
+
+#define NS_ENSURE_SUCCESS_BODY(res, ret)                                  \
+    char *msg = PR_smprintf("NS_ENSURE_SUCCESS(%s, %s) failed with "      \
+                            "result 0x%X", #res, #ret, __rv);             \
+    NS_WARNING(msg);                                                      \
+    PR_smprintf_free(msg);
+
+#define NS_ENSURE_SUCCESS_BODY_VOID(res)                                  \
+    char *msg = PR_smprintf("NS_ENSURE_SUCCESS_VOID(%s) failed with "     \
+                            "result 0x%X", #res, __rv);                   \
+    NS_WARNING(msg);                                                      \
+    PR_smprintf_free(msg);
+
+#else
+
+#define NS_ENSURE_SUCCESS_BODY(res, ret)                                  \
+    NS_WARNING("NS_ENSURE_SUCCESS(" #res ", " #ret ") failed");
+
+#define NS_ENSURE_SUCCESS_BODY_VOID(res)                                  \
+    NS_WARNING("NS_ENSURE_SUCCESS_VOID(" #res ") failed");
+
+#endif
+
+#define NS_ENSURE_SUCCESS(res, ret)                                       \
+  do {                                                                    \
+    nsresult __rv = res; /* Don't evaluate |res| more than once */        \
+    if (NS_FAILED(__rv)) {                                                \
+      NS_ENSURE_SUCCESS_BODY(res, ret)                                    \
+      return ret;                                                         \
+    }                                                                     \
+  } while(0)
+
+#define NS_ENSURE_SUCCESS_VOID(res)                                       \
+  do {                                                                    \
+    nsresult __rv = res;                                                  \
+    if (NS_FAILED(__rv)) {                                                \
+      NS_ENSURE_SUCCESS_BODY_VOID(res)                                    \
+      return;                                                             \
+    }                                                                     \
+  } while(0)
+
+/******************************************************************************
+** Macros for checking state and arguments upon entering interface boundaries
+******************************************************************************/
+
+#define NS_ENSURE_ARG(arg)                                    \
+  NS_ENSURE_TRUE(arg, NS_ERROR_INVALID_ARG)
+
+#define NS_ENSURE_ARG_POINTER(arg)                            \
+  NS_ENSURE_TRUE(arg, NS_ERROR_INVALID_POINTER)
+
+#define NS_ENSURE_ARG_MIN(arg, min)                           \
+  NS_ENSURE_TRUE((arg) >= min, NS_ERROR_INVALID_ARG)
+
+#define NS_ENSURE_ARG_MAX(arg, max)                           \
+  NS_ENSURE_TRUE((arg) <= max, NS_ERROR_INVALID_ARG)
+
+#define NS_ENSURE_ARG_RANGE(arg, min, max)                    \
+  NS_ENSURE_TRUE(((arg) >= min) && ((arg) <= max), NS_ERROR_INVALID_ARG)
+
+#define NS_ENSURE_STATE(state)                                \
+  NS_ENSURE_TRUE(state, NS_ERROR_UNEXPECTED)
+
+#define NS_ENSURE_NO_AGGREGATION(outer)                       \
+  NS_ENSURE_FALSE(outer, NS_ERROR_NO_AGGREGATION)
+
+/*****************************************************************************/
+
+#if (defined(DEBUG) || (defined(NIGHTLY_BUILD) && !defined(MOZ_PROFILING))) && !defined(XPCOM_GLUE_AVOID_NSPR)
+  #define MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED  1
+#endif
+
+#ifdef XPCOM_GLUE
+  #define NS_CheckThreadSafe(owningThread, msg)
+#else
+  #define NS_CheckThreadSafe(owningThread, msg)                 \
+    if (MOZ_UNLIKELY(owningThread != PR_GetCurrentThread())) {  \
+      MOZ_CRASH(msg);                                           \
+    }
+#endif
+
+#ifdef MOZILLA_INTERNAL_API
+void NS_ABORT_OOM(size_t aSize);
+#else
+inline void NS_ABORT_OOM(size_t)
+{
+  MOZ_CRASH();
+}
+#endif
+
+typedef void (*StderrCallback)(const char* aFmt, va_list aArgs);
+/* When compiling the XPCOM Glue on Windows, we pretend that it's going to
+ * be linked with a static CRT (-MT) even when it's not. This means that we
+ * cannot link to data exports from the CRT, only function exports. So,
+ * instead of referencing "stderr" directly, use fdopen.
+ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * printf_stderr(...) is much like fprintf(stderr, ...), except that:
+ *  - it calls the callback set through set_stderr_callback
+ *  - on Android and Firefox OS, *instead* of printing to stderr, it
+ *    prints to logcat.  (Newlines in the string lead to multiple lines
+ *    of logcat, but each function call implicitly completes a line even
+ *    if the string does not end with a newline.)
+ *  - on Windows, if a debugger is present, it calls OutputDebugString
+ *    in *addition* to writing to stderr
+ */
+void printf_stderr(const char* aFmt, ...) MOZ_FORMAT_PRINTF(1, 2);
+
+/**
+ * Same as printf_stderr, but taking va_list instead of varargs
+ */
+void vprintf_stderr(const char* aFmt, va_list aArgs);
+
+/**
+ * fprintf_stderr is like fprintf, except that if its file argument
+ * is stderr, it invokes printf_stderr instead.
+ *
+ * This is useful for general debugging code that logs information to a
+ * file, but that you would like to be useful on Android and Firefox OS.
+ * If you use fprintf_stderr instead of fprintf in such debugging code,
+ * then callers can pass stderr to get logging that works on Android and
+ * Firefox OS (and also the other side-effects of using printf_stderr).
+ *
+ * Code that is structured this way needs to be careful not to split a
+ * line of output across multiple calls to fprintf_stderr, since doing
+ * so will cause it to appear in multiple lines in logcat output.
+ * (Producing multiple lines at once is fine.)
+ */
+void fprintf_stderr(FILE* aFile, const char* aFmt, ...) MOZ_FORMAT_PRINTF(2, 3);
+
+// used by the profiler to log stderr in the profiler for more
+// advanced performance debugging and display/layers visualization.
+void set_stderr_callback(StderrCallback aCallback);
+
+#if defined(ANDROID) && !defined(RELEASE_OR_BETA)
+// Call this if you want a copy of stderr logging sent to a file. This is
+// useful to get around logcat overflow problems on android devices, which use
+// a circular logcat buffer and can intermittently drop messages if there's too
+// much spew.
+//
+// This is intended for local debugging only, DO NOT USE IN PRODUCTION CODE.
+// (This is ifndef RELEASE_OR_BETA to catch uses of it that accidentally get
+// checked in). Using this will also prevent the profiler from getting a copy of
+// the stderr messages which it uses for various visualization features.
+//
+// This function can be called from any thread, but if it is called multiple
+// times all invocations must be on the same thread. Invocations after the
+// first one are ignored, so you can safely put it inside a loop, for example.
+// Once this is called there is no way to turn it off; all stderr output from
+// that point forward will go to the file. Note that the output is subject to
+// buffering so make sure you have enough output to flush the messages you care
+// about before you terminate the process.
+//
+// The file passed in should be writable, so on Android devices a path like
+// "/data/local/tmp/blah" is a good one to use as it is world-writable and will
+// work even in B2G child processes which have reduced privileges. Note that the
+// actual file created will have the PID appended to the path you pass in, so
+// that on B2G the output from each process goes to a separate file.
+void copy_stderr_to_file(const char* aFile);
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* nsDebug_h___ */
diff --git a/xpcom/glue/nsDeque.cpp b/xpcom/glue/nsDeque.cpp
new file mode 100644
index 0000000000..f9eb18b405
--- /dev/null
+++ b/xpcom/glue/nsDeque.cpp
@@ -0,0 +1,361 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsDeque.h"
+#include "nsISupportsImpl.h"
+#include <string.h>
+#ifdef DEBUG_rickg
+#include <stdio.h>
+#endif
+
+#include "mozilla/CheckedInt.h"
+
+#define modulus(x,y) ((x)%(y))
+
+/**
+ * Standard constructor
+ * @param deallocator, called by Erase and ~nsDeque
+ */
+nsDeque::nsDeque(nsDequeFunctor* aDeallocator)
+{
+  MOZ_COUNT_CTOR(nsDeque);
+  mDeallocator = aDeallocator;
+  mOrigin = mSize = 0;
+  mData = mBuffer; // don't allocate space until you must
+  mCapacity = sizeof(mBuffer) / sizeof(mBuffer[0]);
+  memset(mData, 0, mCapacity * sizeof(mBuffer[0]));
+}
+
+/**
+ * Destructor
+ */
+nsDeque::~nsDeque()
+{
+  MOZ_COUNT_DTOR(nsDeque);
+
+#ifdef DEBUG_rickg
+  char buffer[30];
+  printf("Capacity: %i\n", mCapacity);
+
+  static int mCaps[15] = {0};
+  switch (mCapacity) {
+    case 4:     mCaps[0]++; break;
+    case 8:     mCaps[1]++; break;
+    case 16:    mCaps[2]++; break;
+    case 32:    mCaps[3]++; break;
+    case 64:    mCaps[4]++; break;
+    case 128:   mCaps[5]++; break;
+    case 256:   mCaps[6]++; break;
+    case 512:   mCaps[7]++; break;
+    case 1024:  mCaps[8]++; break;
+    case 2048:  mCaps[9]++; break;
+    case 4096:  mCaps[10]++; break;
+    default:
+      break;
+  }
+#endif
+
+  Erase();
+  if (mData && mData != mBuffer) {
+    free(mData);
+  }
+  mData = 0;
+  SetDeallocator(0);
+}
+
+size_t
+nsDeque::SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  size_t size = 0;
+  if (mData != mBuffer) {
+    size += aMallocSizeOf(mData);
+  }
+
+  if (mDeallocator) {
+    size += aMallocSizeOf(mDeallocator);
+  }
+
+  return size;
+}
+
+size_t
+nsDeque::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+}
+
+/**
+ * Set the functor to be called by Erase()
+ * The deque owns the functor.
+ *
+ * @param   aDeallocator functor object for use by Erase()
+ */
+void
+nsDeque::SetDeallocator(nsDequeFunctor* aDeallocator)
+{
+  delete mDeallocator;
+  mDeallocator = aDeallocator;
+}
+
+/**
+ * Remove all items from container without destroying them.
+ */
+void
+nsDeque::Empty()
+{
+  if (mSize && mData) {
+    memset(mData, 0, mCapacity * sizeof(*mData));
+  }
+  mSize = 0;
+  mOrigin = 0;
+}
+
+/**
+ * Remove and delete all items from container
+ */
+void
+nsDeque::Erase()
+{
+  if (mDeallocator && mSize) {
+    ForEach(*mDeallocator);
+  }
+  Empty();
+}
+
+/**
+ * This method quadruples the size of the deque
+ * Elements in the deque are resequenced so that elements
+ * in the deque are stored sequentially
+ *
+ * @return  whether growing succeeded
+ */
+bool
+nsDeque::GrowCapacity()
+{
+  mozilla::CheckedInt<size_t> newCapacity = mCapacity;
+  newCapacity *= 4;
+
+  NS_ASSERTION(newCapacity.isValid(), "Overflow");
+  if (!newCapacity.isValid()) {
+    return false;
+  }
+
+  // Sanity check the new byte size.
+  mozilla::CheckedInt<size_t> newByteSize = newCapacity;
+  newByteSize *= sizeof(void*);
+
+  NS_ASSERTION(newByteSize.isValid(), "Overflow");
+  if (!newByteSize.isValid()) {
+    return false;
+  }
+
+  void** temp = (void**)malloc(newByteSize.value());
+  if (!temp) {
+    return false;
+  }
+
+  //Here's the interesting part: You can't just move the elements
+  //directly (in situ) from the old buffer to the new one.
+  //Since capacity has changed, the old origin doesn't make
+  //sense anymore. It's better to resequence the elements now.
+
+  memcpy(temp, mData + mOrigin, sizeof(void*) * (mCapacity - mOrigin));
+  memcpy(temp + (mCapacity - mOrigin), mData, sizeof(void*) * mOrigin);
+
+  if (mData != mBuffer) {
+    free(mData);
+  }
+
+  mCapacity = newCapacity.value();
+  mOrigin = 0; //now realign the origin...
+  mData = temp;
+
+  return true;
+}
+
+/**
+ * This method adds an item to the end of the deque.
+ * This operation has the potential to cause the
+ * underlying buffer to resize.
+ *
+ * @param   aItem: new item to be added to deque
+ */
+bool
+nsDeque::Push(void* aItem, const fallible_t&)
+{
+  if (mSize == mCapacity && !GrowCapacity()) {
+    return false;
+  }
+  mData[modulus(mOrigin + mSize, mCapacity)] = aItem;
+  mSize++;
+  return true;
+}
+
+/**
+ * This method adds an item to the front of the deque.
+ * This operation has the potential to cause the
+ * underlying buffer to resize.
+ *
+ * --Commments for GrowCapacity() case
+ * We've grown and shifted which means that the old
+ * final element in the deque is now the first element
+ * in the deque.  This is temporary.
+ * We haven't inserted the new element at the front.
+ *
+ * To continue with the idea of having the front at zero
+ * after a grow, we move the old final item (which through
+ * the voodoo of mOrigin-- is now the first) to its final
+ * position which is conveniently the old length.
+ *
+ * Note that this case only happens when the deque is full.
+ * [And that pieces of this magic only work if the deque is full.]
+ * picture:
+ *   [ABCDEFGH] @[mOrigin:3]:D.
+ * Task: PushFront("Z")
+ * shift mOrigin so, @[mOrigin:2]:C
+ * stretch and rearrange: (mOrigin:0)
+ *   [CDEFGHAB ________ ________ ________]
+ * copy: (The second C is currently out of bounds)
+ *   [CDEFGHAB C_______ ________ ________]
+ * later we will insert Z:
+ *   [ZDEFGHAB C_______ ________ ________]
+ * and increment size: 9. (C is no longer out of bounds)
+ * --
+ * @param   aItem: new item to be added to deque
+ */
+bool
+nsDeque::PushFront(void* aItem, const fallible_t&)
+{
+  
+  if (mOrigin == 0) {
+    mOrigin = mCapacity - 1;
+  } else {
+    mOrigin--;
+  }
+  
+  if (mSize == mCapacity) {
+    if (!GrowCapacity()) {
+      return false;
+    }
+    /* Comments explaining this are above*/
+    mData[mSize] = mData[mOrigin];
+  }
+  mData[mOrigin] = aItem;
+  mSize++;
+  return true;
+}
+
+/**
+ * Remove and return the last item in the container.
+ *
+ * @return  ptr to last item in container
+ */
+void*
+nsDeque::Pop()
+{
+  void* result = 0;
+  if (mSize > 0) {
+    --mSize;
+    size_t offset = modulus(mSize + mOrigin, mCapacity);
+    result = mData[offset];
+    mData[offset] = 0;
+    if (!mSize) {
+      mOrigin = 0;
+    }
+  }
+  return result;
+}
+
+/**
+ * This method gets called you want to remove and return
+ * the first member in the container.
+ *
+ * @return  last item in container
+ */
+void*
+nsDeque::PopFront()
+{
+  void* result = 0;
+  if (mSize > 0) {
+    NS_ASSERTION(mOrigin < mCapacity, "Error: Bad origin");
+    result = mData[mOrigin];
+    mData[mOrigin++] = 0;   //zero it out for debugging purposes.
+    mSize--;
+    // Cycle around if we pop off the end
+    // and reset origin if when we pop the last element
+    if (mCapacity == mOrigin || !mSize) {
+      mOrigin = 0;
+    }
+  }
+  return result;
+}
+
+/**
+ * This method gets called you want to peek at the bottom
+ * member without removing it.
+ *
+ * @return  last item in container
+ */
+void*
+nsDeque::Peek() const
+{
+  void* result = 0;
+  if (mSize > 0) {
+    result = mData[modulus(mSize - 1 + mOrigin, mCapacity)];
+  }
+  return result;
+}
+
+/**
+ * This method gets called you want to peek at the topmost
+ * member without removing it.
+ *
+ * @return  last item in container
+ */
+void*
+nsDeque::PeekFront() const
+{
+  void* result = 0;
+  if (mSize > 0) {
+    result = mData[mOrigin];
+  }
+  return result;
+}
+
+/**
+ * Call this to retrieve the ith element from this container.
+ * Keep in mind that accessing the underlying elements is
+ * done in a relative fashion. Object 0 is not necessarily
+ * the first element (the first element is at mOrigin).
+ *
+ * @param   aIndex : 0 relative offset of item you want
+ * @return  void* or null
+ */
+void*
+nsDeque::ObjectAt(size_t aIndex) const
+{
+  void* result = 0;
+  if (aIndex < mSize) {
+    result = mData[modulus(mOrigin + aIndex, mCapacity)];
+  }
+  return result;
+}
+
+/**
+ * Call this method when you want to iterate all the
+ * members of the container, passing a functor along
+ * to call your code.
+ *
+ * @param   aFunctor object to call for each member
+ * @return  *this
+ */
+void
+nsDeque::ForEach(nsDequeFunctor& aFunctor) const
+{
+  for (size_t i = 0; i < mSize; ++i) {
+    aFunctor(ObjectAt(i));
+  }
+}
diff --git a/xpcom/glue/nsDeque.h b/xpcom/glue/nsDeque.h
new file mode 100644
index 0000000000..ace7607d39
--- /dev/null
+++ b/xpcom/glue/nsDeque.h
@@ -0,0 +1,195 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * MODULE NOTES:
+ *
+ * The Deque is a very small, very efficient container object
+ * than can hold elements of type void*, offering the following features:
+ *    Its interface supports pushing and popping of elements.
+ *    It can iterate (via an interator class) its elements.
+ *    When full, it can efficiently resize dynamically.
+ *
+ *
+ * NOTE: The only bit of trickery here is that this deque is
+ * built upon a ring-buffer. Like all ring buffers, the first
+ * element may not be at index[0]. The mOrigin member determines
+ * where the first child is. This point is quietly hidden from
+ * customers of this class.
+ *
+ */
+
+#ifndef _NSDEQUE
+#define _NSDEQUE
+
+#include "nscore.h"
+#include "nsDebug.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/fallible.h"
+#include "mozilla/MemoryReporting.h"
+
+/**
+ * The nsDequeFunctor class is used when you want to create
+ * callbacks between the deque and your generic code.
+ * Use these objects in a call to ForEach();
+ *
+ */
+
+class nsDequeFunctor
+{
+public:
+  virtual void* operator()(void* aObject) = 0;
+  virtual ~nsDequeFunctor() {}
+};
+
+/******************************************************
+ * Here comes the nsDeque class itself...
+ ******************************************************/
+
+/**
+ * The deque (double-ended queue) class is a common container type,
+ * whose behavior mimics a line in your favorite checkout stand.
+ * Classic CS describes the common behavior of a queue as FIFO.
+ * A deque allows insertion and removal at both ends of
+ * the container.
+ *
+ * The deque stores pointers to items.
+ */
+
+class nsDequeIterator;
+
+class nsDeque
+{
+  typedef mozilla::fallible_t fallible_t;
+public:
+  explicit nsDeque(nsDequeFunctor* aDeallocator = nullptr);
+  ~nsDeque();
+
+  /**
+   * Returns the number of elements currently stored in
+   * this deque.
+   *
+   * @return  number of elements currently in the deque
+   */
+  inline size_t GetSize() const { return mSize; }
+
+  /**
+   * Appends new member at the end of the deque.
+   *
+   * @param   item to store in deque
+   */
+  void Push(void* aItem)
+  {
+    if (!Push(aItem, mozilla::fallible)) {
+      NS_ABORT_OOM(mSize * sizeof(void*));
+    }
+  }
+
+  MOZ_MUST_USE bool Push(void* aItem, const fallible_t&);
+
+  /**
+   * Inserts new member at the front of the deque.
+   *
+   * @param   item to store in deque
+   */
+  void PushFront(void* aItem)
+  {
+    if (!PushFront(aItem, mozilla::fallible)) {
+      NS_ABORT_OOM(mSize * sizeof(void*));
+    }
+  }
+
+  MOZ_MUST_USE bool PushFront(void* aItem, const fallible_t&);
+
+  /**
+   * Remove and return the last item in the container.
+   *
+   * @return  the item that was the last item in container
+   */
+  void* Pop();
+
+  /**
+   * Remove and return the first item in the container.
+   *
+   * @return  the item that was first item in container
+   */
+  void* PopFront();
+
+  /**
+   * Retrieve the bottom item without removing it.
+   *
+   * @return  the first item in container
+   */
+
+  void* Peek() const;
+  /**
+   * Return topmost item without removing it.
+   *
+   * @return  the first item in container
+   */
+  void* PeekFront() const;
+
+  /**
+   * Retrieve a member from the deque without removing it.
+   *
+   * @param   index of desired item
+   * @return  element in list
+   */
+  void* ObjectAt(size_t aIndex) const;
+
+  /**
+   * Remove and delete all items from container.
+   * Deletes are handled by the deallocator nsDequeFunctor
+   * which is specified at deque construction.
+   */
+  void Erase();
+
+  /**
+   * Call this method when you want to iterate all the
+   * members of the container, passing a functor along
+   * to call your code.
+   *
+   * @param   aFunctor object to call for each member
+   */
+  void ForEach(nsDequeFunctor& aFunctor) const;
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+protected:
+  size_t         mSize;
+  size_t         mCapacity;
+  size_t         mOrigin;
+  nsDequeFunctor* mDeallocator;
+  void*           mBuffer[8];
+  void**          mData;
+
+private:
+
+  /**
+   * Copy constructor (PRIVATE)
+   *
+   * @param aOther another deque
+   */
+  nsDeque(const nsDeque& aOther);
+
+  /**
+   * Deque assignment operator (PRIVATE)
+   *
+   * @param aOther another deque
+   * @return *this
+   */
+  nsDeque& operator=(const nsDeque& aOther);
+
+  bool GrowCapacity();
+  void SetDeallocator(nsDequeFunctor* aDeallocator);
+
+  /**
+   * Remove all items from container without destroying them.
+   */
+  void Empty();
+};
+#endif
diff --git a/xpcom/glue/nsEnumeratorUtils.cpp b/xpcom/glue/nsEnumeratorUtils.cpp
new file mode 100644
index 0000000000..d1843a78ad
--- /dev/null
+++ b/xpcom/glue/nsEnumeratorUtils.cpp
@@ -0,0 +1,291 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Attributes.h"
+
+#include "nsEnumeratorUtils.h"
+
+#include "nsISimpleEnumerator.h"
+#include "nsIStringEnumerator.h"
+
+#include "nsCOMPtr.h"
+#include "mozilla/RefPtr.h"
+
+class EmptyEnumeratorImpl
+  : public nsISimpleEnumerator
+  , public nsIUTF8StringEnumerator
+  , public nsIStringEnumerator
+{
+public:
+  EmptyEnumeratorImpl() {}
+
+  // nsISupports interface
+  NS_DECL_ISUPPORTS_INHERITED  // not really inherited, but no mRefCnt
+
+  // nsISimpleEnumerator
+  NS_DECL_NSISIMPLEENUMERATOR
+  NS_DECL_NSIUTF8STRINGENUMERATOR
+  // can't use NS_DECL_NSISTRINGENUMERATOR because they share the
+  // HasMore() signature
+  NS_IMETHOD GetNext(nsAString& aResult) override;
+
+  static EmptyEnumeratorImpl* GetInstance()
+  {
+    static const EmptyEnumeratorImpl kInstance;
+    return const_cast<EmptyEnumeratorImpl*>(&kInstance);
+  }
+};
+
+// nsISupports interface
+NS_IMETHODIMP_(MozExternalRefCountType)
+EmptyEnumeratorImpl::AddRef(void)
+{
+  return 2;
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+EmptyEnumeratorImpl::Release(void)
+{
+  return 1;
+}
+
+NS_IMPL_QUERY_INTERFACE(EmptyEnumeratorImpl, nsISimpleEnumerator,
+                        nsIUTF8StringEnumerator, nsIStringEnumerator)
+
+// nsISimpleEnumerator interface
+NS_IMETHODIMP
+EmptyEnumeratorImpl::HasMoreElements(bool* aResult)
+{
+  *aResult = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+EmptyEnumeratorImpl::HasMore(bool* aResult)
+{
+  *aResult = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+EmptyEnumeratorImpl::GetNext(nsISupports** aResult)
+{
+  return NS_ERROR_UNEXPECTED;
+}
+
+NS_IMETHODIMP
+EmptyEnumeratorImpl::GetNext(nsACString& aResult)
+{
+  return NS_ERROR_UNEXPECTED;
+}
+
+NS_IMETHODIMP
+EmptyEnumeratorImpl::GetNext(nsAString& aResult)
+{
+  return NS_ERROR_UNEXPECTED;
+}
+
+nsresult
+NS_NewEmptyEnumerator(nsISimpleEnumerator** aResult)
+{
+  *aResult = EmptyEnumeratorImpl::GetInstance();
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+class nsSingletonEnumerator final : public nsISimpleEnumerator
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // nsISimpleEnumerator methods
+  NS_IMETHOD HasMoreElements(bool* aResult) override;
+  NS_IMETHOD GetNext(nsISupports** aResult) override;
+
+  explicit nsSingletonEnumerator(nsISupports* aValue);
+
+private:
+  ~nsSingletonEnumerator();
+
+protected:
+  nsCOMPtr<nsISupports> mValue;
+  bool mConsumed;
+};
+
+nsSingletonEnumerator::nsSingletonEnumerator(nsISupports* aValue)
+  : mValue(aValue)
+{
+  mConsumed = (mValue ? false : true);
+}
+
+nsSingletonEnumerator::~nsSingletonEnumerator()
+{
+}
+
+NS_IMPL_ISUPPORTS(nsSingletonEnumerator, nsISimpleEnumerator)
+
+NS_IMETHODIMP
+nsSingletonEnumerator::HasMoreElements(bool* aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  *aResult = !mConsumed;
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsSingletonEnumerator::GetNext(nsISupports** aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (mConsumed) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  mConsumed = true;
+
+  *aResult = mValue;
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+nsresult
+NS_NewSingletonEnumerator(nsISimpleEnumerator** aResult,
+                          nsISupports* aSingleton)
+{
+  RefPtr<nsSingletonEnumerator> enumer = new nsSingletonEnumerator(aSingleton);
+  enumer.forget(aResult);
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+class nsUnionEnumerator final : public nsISimpleEnumerator
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // nsISimpleEnumerator methods
+  NS_IMETHOD HasMoreElements(bool* aResult) override;
+  NS_IMETHOD GetNext(nsISupports** aResult) override;
+
+  nsUnionEnumerator(nsISimpleEnumerator* aFirstEnumerator,
+                    nsISimpleEnumerator* aSecondEnumerator);
+
+private:
+  ~nsUnionEnumerator();
+
+protected:
+  nsCOMPtr<nsISimpleEnumerator> mFirstEnumerator, mSecondEnumerator;
+  bool mConsumed;
+  bool mAtSecond;
+};
+
+nsUnionEnumerator::nsUnionEnumerator(nsISimpleEnumerator* aFirstEnumerator,
+                                     nsISimpleEnumerator* aSecondEnumerator)
+  : mFirstEnumerator(aFirstEnumerator)
+  , mSecondEnumerator(aSecondEnumerator)
+  , mConsumed(false)
+  , mAtSecond(false)
+{
+}
+
+nsUnionEnumerator::~nsUnionEnumerator()
+{
+}
+
+NS_IMPL_ISUPPORTS(nsUnionEnumerator, nsISimpleEnumerator)
+
+NS_IMETHODIMP
+nsUnionEnumerator::HasMoreElements(bool* aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  nsresult rv;
+
+  if (mConsumed) {
+    *aResult = false;
+    return NS_OK;
+  }
+
+  if (!mAtSecond) {
+    rv = mFirstEnumerator->HasMoreElements(aResult);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    if (*aResult) {
+      return NS_OK;
+    }
+
+    mAtSecond = true;
+  }
+
+  rv = mSecondEnumerator->HasMoreElements(aResult);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (*aResult) {
+    return NS_OK;
+  }
+
+  *aResult = false;
+  mConsumed = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsUnionEnumerator::GetNext(nsISupports** aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (mConsumed) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (!mAtSecond) {
+    return mFirstEnumerator->GetNext(aResult);
+  }
+
+  return mSecondEnumerator->GetNext(aResult);
+}
+
+nsresult
+NS_NewUnionEnumerator(nsISimpleEnumerator** aResult,
+                      nsISimpleEnumerator* aFirstEnumerator,
+                      nsISimpleEnumerator* aSecondEnumerator)
+{
+  *aResult = nullptr;
+  if (!aFirstEnumerator) {
+    *aResult = aSecondEnumerator;
+  } else if (!aSecondEnumerator) {
+    *aResult = aFirstEnumerator;
+  } else {
+    nsUnionEnumerator* enumer = new nsUnionEnumerator(aFirstEnumerator,
+                                                      aSecondEnumerator);
+    if (!enumer) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    *aResult = enumer;
+  }
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
diff --git a/xpcom/glue/nsEnumeratorUtils.h b/xpcom/glue/nsEnumeratorUtils.h
new file mode 100644
index 0000000000..f7a0db099e
--- /dev/null
+++ b/xpcom/glue/nsEnumeratorUtils.h
@@ -0,0 +1,24 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsEnumeratorUtils_h__
+#define nsEnumeratorUtils_h__
+
+#include "nscore.h"
+
+class nsISupports;
+class nsISimpleEnumerator;
+
+nsresult NS_NewEmptyEnumerator(nsISimpleEnumerator** aResult);
+
+nsresult NS_NewSingletonEnumerator(nsISimpleEnumerator** aResult,
+                                   nsISupports* aSingleton);
+
+nsresult NS_NewUnionEnumerator(nsISimpleEnumerator** aResult,
+                               nsISimpleEnumerator* aFirstEnumerator,
+                               nsISimpleEnumerator* aSecondEnumerator);
+
+#endif /* nsEnumeratorUtils_h__ */
diff --git a/xpcom/glue/nsHashKeys.h b/xpcom/glue/nsHashKeys.h
new file mode 100644
index 0000000000..9c688691fc
--- /dev/null
+++ b/xpcom/glue/nsHashKeys.h
@@ -0,0 +1,660 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTHashKeys_h__
+#define nsTHashKeys_h__
+
+#include "nsID.h"
+#include "nsISupports.h"
+#include "nsIHashable.h"
+#include "nsAutoPtr.h"
+#include "nsCOMPtr.h"
+#include "PLDHashTable.h"
+#include <new>
+
+#include "nsStringGlue.h"
+#include "nsCRTGlue.h"
+#include "nsUnicharUtils.h"
+#include "nsPointerHashKeys.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "mozilla/HashFunctions.h"
+#include "mozilla/Move.h"
+
+namespace mozilla {
+
+// These are defined analogously to the HashString overloads in mfbt.
+
+inline uint32_t
+HashString(const nsAString& aStr)
+{
+  return HashString(aStr.BeginReading(), aStr.Length());
+}
+
+inline uint32_t
+HashString(const nsACString& aStr)
+{
+  return HashString(aStr.BeginReading(), aStr.Length());
+}
+
+} // namespace mozilla
+
+/** @file nsHashKeys.h
+ * standard HashKey classes for nsBaseHashtable and relatives. Each of these
+ * classes follows the nsTHashtable::EntryType specification
+ *
+ * Lightweight keytypes provided here:
+ * nsStringHashKey
+ * nsCStringHashKey
+ * nsUint32HashKey
+ * nsUint64HashKey
+ * nsFloatHashKey
+ * nsPtrHashKey
+ * nsClearingPtrHashKey
+ * nsVoidPtrHashKey
+ * nsClearingVoidPtrHashKey
+ * nsISupportsHashKey
+ * nsIDHashKey
+ * nsDepCharHashKey
+ * nsCharPtrHashKey
+ * nsUnicharPtrHashKey
+ * nsHashableHashKey
+ * nsGenericHashKey
+ */
+
+/**
+ * hashkey wrapper using nsAString KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsStringHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const nsAString& KeyType;
+  typedef const nsAString* KeyTypePointer;
+
+  explicit nsStringHashKey(KeyTypePointer aStr) : mStr(*aStr) {}
+  nsStringHashKey(const nsStringHashKey& aToCopy) : mStr(aToCopy.mStr) {}
+  ~nsStringHashKey() {}
+
+  KeyType GetKey() const { return mStr; }
+  bool KeyEquals(const KeyTypePointer aKey) const
+  {
+    return mStr.Equals(*aKey);
+  }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(const KeyTypePointer aKey)
+  {
+    return mozilla::HashString(*aKey);
+  }
+
+#ifdef MOZILLA_INTERNAL_API
+  // To avoid double-counting, only measure the string if it is unshared.
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return GetKey().SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+  }
+#endif
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const nsString mStr;
+};
+
+#ifdef MOZILLA_INTERNAL_API
+
+/**
+ * hashkey wrapper using nsAString KeyType
+ *
+ * This is internal-API only because nsCaseInsensitiveStringComparator is
+ * internal-only.
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsStringCaseInsensitiveHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const nsAString& KeyType;
+  typedef const nsAString* KeyTypePointer;
+
+  explicit nsStringCaseInsensitiveHashKey(KeyTypePointer aStr)
+    : mStr(*aStr)
+  {
+    // take it easy just deal HashKey
+  }
+  nsStringCaseInsensitiveHashKey(const nsStringCaseInsensitiveHashKey& aToCopy)
+    : mStr(aToCopy.mStr)
+  {
+  }
+  ~nsStringCaseInsensitiveHashKey() {}
+
+  KeyType GetKey() const { return mStr; }
+  bool KeyEquals(const KeyTypePointer aKey) const
+  {
+    return mStr.Equals(*aKey, nsCaseInsensitiveStringComparator());
+  }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(const KeyTypePointer aKey)
+  {
+    nsAutoString tmKey(*aKey);
+    ToLowerCase(tmKey);
+    return mozilla::HashString(tmKey);
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+  // To avoid double-counting, only measure the string if it is unshared.
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return GetKey().SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+  }
+
+private:
+  const nsString mStr;
+};
+
+#endif
+
+/**
+ * hashkey wrapper using nsACString KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsCStringHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const nsACString& KeyType;
+  typedef const nsACString* KeyTypePointer;
+
+  explicit nsCStringHashKey(const nsACString* aStr) : mStr(*aStr) {}
+  nsCStringHashKey(const nsCStringHashKey& aToCopy) : mStr(aToCopy.mStr) {}
+  ~nsCStringHashKey() {}
+
+  KeyType GetKey() const { return mStr; }
+  bool KeyEquals(KeyTypePointer aKey) const { return mStr.Equals(*aKey); }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return mozilla::HashString(*aKey);
+  }
+
+#ifdef MOZILLA_INTERNAL_API
+  // To avoid double-counting, only measure the string if it is unshared.
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return GetKey().SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+  }
+#endif
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const nsCString mStr;
+};
+
+/**
+ * hashkey wrapper using uint32_t KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsUint32HashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const uint32_t& KeyType;
+  typedef const uint32_t* KeyTypePointer;
+
+  explicit nsUint32HashKey(KeyTypePointer aKey) : mValue(*aKey) {}
+  nsUint32HashKey(const nsUint32HashKey& aToCopy) : mValue(aToCopy.mValue) {}
+  ~nsUint32HashKey() {}
+
+  KeyType GetKey() const { return mValue; }
+  bool KeyEquals(KeyTypePointer aKey) const { return *aKey == mValue; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey) { return *aKey; }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const uint32_t mValue;
+};
+
+/**
+ * hashkey wrapper using uint64_t KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsUint64HashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const uint64_t& KeyType;
+  typedef const uint64_t* KeyTypePointer;
+
+  explicit nsUint64HashKey(KeyTypePointer aKey) : mValue(*aKey) {}
+  nsUint64HashKey(const nsUint64HashKey& aToCopy) : mValue(aToCopy.mValue) {}
+  ~nsUint64HashKey() {}
+
+  KeyType GetKey() const { return mValue; }
+  bool KeyEquals(KeyTypePointer aKey) const { return *aKey == mValue; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return PLDHashNumber(*aKey);
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const uint64_t mValue;
+};
+
+/**
+ * hashkey wrapper using float KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsFloatHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const float& KeyType;
+  typedef const float* KeyTypePointer;
+
+  explicit nsFloatHashKey(KeyTypePointer aKey) : mValue(*aKey) {}
+  nsFloatHashKey(const nsFloatHashKey& aToCopy) : mValue(aToCopy.mValue) {}
+  ~nsFloatHashKey() {}
+
+  KeyType GetKey() const { return mValue; }
+  bool KeyEquals(KeyTypePointer aKey) const { return *aKey == mValue; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return *reinterpret_cast<const uint32_t*>(aKey);
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const float mValue;
+};
+
+/**
+ * hashkey wrapper using nsISupports* KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsISupportsHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef nsISupports* KeyType;
+  typedef const nsISupports* KeyTypePointer;
+
+  explicit nsISupportsHashKey(const nsISupports* aKey)
+    : mSupports(const_cast<nsISupports*>(aKey))
+  {
+  }
+  nsISupportsHashKey(const nsISupportsHashKey& aToCopy)
+    : mSupports(aToCopy.mSupports)
+  {
+  }
+  ~nsISupportsHashKey() {}
+
+  KeyType GetKey() const { return mSupports; }
+  bool KeyEquals(KeyTypePointer aKey) const { return aKey == mSupports; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return NS_PTR_TO_UINT32(aKey) >> 2;
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  nsCOMPtr<nsISupports> mSupports;
+};
+
+/**
+ * hashkey wrapper using refcounted * KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+template<class T>
+class nsRefPtrHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef T* KeyType;
+  typedef const T* KeyTypePointer;
+
+  explicit nsRefPtrHashKey(const T* aKey) : mKey(const_cast<T*>(aKey)) {}
+  nsRefPtrHashKey(const nsRefPtrHashKey& aToCopy) : mKey(aToCopy.mKey) {}
+  ~nsRefPtrHashKey() {}
+
+  KeyType GetKey() const { return mKey; }
+  bool KeyEquals(KeyTypePointer aKey) const { return aKey == mKey; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return NS_PTR_TO_UINT32(aKey) >> 2;
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  RefPtr<T> mKey;
+};
+
+template<class T>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsRefPtrHashKey<T>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  CycleCollectionNoteChild(aCallback, aField.GetKey(), aName, aFlags);
+}
+
+/**
+ * hashkey wrapper using T* KeyType that sets key to nullptr upon
+ * destruction. Relevant only in cases where a memory pointer-scanner
+ * like valgrind might get confused about stale references.
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+
+template<class T>
+class nsClearingPtrHashKey : public nsPtrHashKey<T>
+{
+public:
+  explicit nsClearingPtrHashKey(const T* aKey) : nsPtrHashKey<T>(aKey) {}
+  nsClearingPtrHashKey(const nsClearingPtrHashKey<T>& aToCopy)
+    : nsPtrHashKey<T>(aToCopy)
+  {
+  }
+  ~nsClearingPtrHashKey() { nsPtrHashKey<T>::mKey = nullptr; }
+};
+
+typedef nsClearingPtrHashKey<const void> nsClearingVoidPtrHashKey;
+
+/**
+ * hashkey wrapper using a function pointer KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+template<class T>
+class nsFuncPtrHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef T& KeyType;
+  typedef const T* KeyTypePointer;
+
+  explicit nsFuncPtrHashKey(const T* aKey) : mKey(*const_cast<T*>(aKey)) {}
+  nsFuncPtrHashKey(const nsFuncPtrHashKey<T>& aToCopy) : mKey(aToCopy.mKey) {}
+  ~nsFuncPtrHashKey() {}
+
+  KeyType GetKey() const { return const_cast<T&>(mKey); }
+  bool KeyEquals(KeyTypePointer aKey) const { return *aKey == mKey; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return NS_PTR_TO_UINT32(*aKey) >> 2;
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+protected:
+  T mKey;
+};
+
+/**
+ * hashkey wrapper using nsID KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsIDHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const nsID& KeyType;
+  typedef const nsID* KeyTypePointer;
+
+  explicit nsIDHashKey(const nsID* aInID) : mID(*aInID) {}
+  nsIDHashKey(const nsIDHashKey& aToCopy) : mID(aToCopy.mID) {}
+  ~nsIDHashKey() {}
+
+  KeyType GetKey() const { return mID; }
+  bool KeyEquals(KeyTypePointer aKey) const { return aKey->Equals(mID); }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    // Hash the nsID object's raw bytes.
+    return mozilla::HashBytes(aKey, sizeof(KeyType));
+  }
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const nsID mID;
+};
+
+/**
+ * hashkey wrapper for "dependent" const char*; this class does not "own"
+ * its string pointer.
+ *
+ * This class must only be used if the strings have a lifetime longer than
+ * the hashtable they occupy. This normally occurs only for static
+ * strings or strings that have been arena-allocated.
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsDepCharHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const char* KeyType;
+  typedef const char* KeyTypePointer;
+
+  explicit nsDepCharHashKey(const char* aKey) : mKey(aKey) {}
+  nsDepCharHashKey(const nsDepCharHashKey& aToCopy) : mKey(aToCopy.mKey) {}
+  ~nsDepCharHashKey() {}
+
+  const char* GetKey() const { return mKey; }
+  bool KeyEquals(const char* aKey) const { return !strcmp(mKey, aKey); }
+
+  static const char* KeyToPointer(const char* aKey) { return aKey; }
+  static PLDHashNumber HashKey(const char* aKey)
+  {
+    return mozilla::HashString(aKey);
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const char* mKey;
+};
+
+/**
+ * hashkey wrapper for const char*; at construction, this class duplicates
+ * a string pointed to by the pointer so that it doesn't matter whether or not
+ * the string lives longer than the hash table.
+ */
+class nsCharPtrHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const char* KeyType;
+  typedef const char* KeyTypePointer;
+
+  explicit nsCharPtrHashKey(const char* aKey) : mKey(strdup(aKey)) {}
+  nsCharPtrHashKey(const nsCharPtrHashKey& aToCopy)
+    : mKey(strdup(aToCopy.mKey))
+  {
+  }
+
+  nsCharPtrHashKey(nsCharPtrHashKey&& aOther)
+    : mKey(aOther.mKey)
+  {
+    aOther.mKey = nullptr;
+  }
+
+  ~nsCharPtrHashKey()
+  {
+    if (mKey) {
+      free(const_cast<char*>(mKey));
+    }
+  }
+
+  const char* GetKey() const { return mKey; }
+  bool KeyEquals(KeyTypePointer aKey) const { return !strcmp(mKey, aKey); }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return mozilla::HashString(aKey);
+  }
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(mKey);
+  }
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const char* mKey;
+};
+
+/**
+ * hashkey wrapper for const char16_t*; at construction, this class duplicates
+ * a string pointed to by the pointer so that it doesn't matter whether or not
+ * the string lives longer than the hash table.
+ */
+class nsUnicharPtrHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const char16_t* KeyType;
+  typedef const char16_t* KeyTypePointer;
+
+  explicit nsUnicharPtrHashKey(const char16_t* aKey) : mKey(NS_strdup(aKey)) {}
+  nsUnicharPtrHashKey(const nsUnicharPtrHashKey& aToCopy)
+    : mKey(NS_strdup(aToCopy.mKey))
+  {
+  }
+
+  nsUnicharPtrHashKey(nsUnicharPtrHashKey&& aOther)
+    : mKey(aOther.mKey)
+  {
+    aOther.mKey = nullptr;
+  }
+
+  ~nsUnicharPtrHashKey()
+  {
+    if (mKey) {
+      NS_Free(const_cast<char16_t*>(mKey));
+    }
+  }
+
+  const char16_t* GetKey() const { return mKey; }
+  bool KeyEquals(KeyTypePointer aKey) const { return !NS_strcmp(mKey, aKey); }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return mozilla::HashString(aKey);
+  }
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(mKey);
+  }
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const char16_t* mKey;
+};
+
+/**
+ * Hashtable key class to use with objects that support nsIHashable
+ */
+class nsHashableHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef nsIHashable* KeyType;
+  typedef const nsIHashable* KeyTypePointer;
+
+  explicit nsHashableHashKey(const nsIHashable* aKey)
+    : mKey(const_cast<nsIHashable*>(aKey))
+  {
+  }
+  nsHashableHashKey(const nsHashableHashKey& aToCopy) : mKey(aToCopy.mKey) {}
+  ~nsHashableHashKey() {}
+
+  nsIHashable* GetKey() const { return mKey; }
+
+  bool KeyEquals(const nsIHashable* aKey) const
+  {
+    bool eq;
+    if (NS_SUCCEEDED(mKey->Equals(const_cast<nsIHashable*>(aKey), &eq))) {
+      return eq;
+    }
+    return false;
+  }
+
+  static const nsIHashable* KeyToPointer(nsIHashable* aKey) { return aKey; }
+  static PLDHashNumber HashKey(const nsIHashable* aKey)
+  {
+    uint32_t code = 8888; // magic number if GetHashCode fails :-(
+#ifdef DEBUG
+    nsresult rv =
+#endif
+      const_cast<nsIHashable*>(aKey)->GetHashCode(&code);
+    NS_ASSERTION(NS_SUCCEEDED(rv), "GetHashCode should not throw!");
+    return code;
+  }
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  nsCOMPtr<nsIHashable> mKey;
+};
+
+namespace mozilla {
+
+template <typename T>
+PLDHashNumber
+Hash(const T& aValue)
+{
+  return aValue.Hash();
+}
+
+} // namespace mozilla
+
+/**
+ * Hashtable key class to use with objects for which Hash() and operator==()
+ * are defined.
+ */
+template<typename T>
+class nsGenericHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const T& KeyType;
+  typedef const T* KeyTypePointer;
+
+  explicit nsGenericHashKey(KeyTypePointer aKey) : mKey(*aKey) {}
+  nsGenericHashKey(const nsGenericHashKey<T>& aOther) : mKey(aOther.mKey) {}
+
+  KeyType GetKey() const { return mKey; }
+  bool KeyEquals(KeyTypePointer aKey) const { return *aKey == mKey; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey) { return ::mozilla::Hash(*aKey); }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  T mKey;
+};
+
+#endif // nsTHashKeys_h__
diff --git a/xpcom/glue/nsIClassInfoImpl.h b/xpcom/glue/nsIClassInfoImpl.h
new file mode 100644
index 0000000000..44303f2be9
--- /dev/null
+++ b/xpcom/glue/nsIClassInfoImpl.h
@@ -0,0 +1,179 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsIClassInfoImpl_h__
+#define nsIClassInfoImpl_h__
+
+#include "mozilla/Alignment.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/MacroArgs.h"
+#include "mozilla/MacroForEach.h"
+#include "nsIClassInfo.h"
+#include "nsISupportsImpl.h"
+
+#include <new>
+
+/**
+ * This header file provides macros which help you make your class implement
+ * nsIClassInfo.  Implementing nsIClassInfo is particularly helpful if you have
+ * a C++ class which implements multiple interfaces and which you access from
+ * JavaScript.  If that class implements nsIClassInfo, the JavaScript code
+ * won't have to call QueryInterface on instances of the class; all methods
+ * from all interfaces returned by GetInterfaces() will be available
+ * automagically.
+ *
+ * Here's all you need to do.  Given a class
+ *
+ *   class nsFooBar : public nsIFoo, public nsIBar { };
+ *
+ * you should already have the following nsISupports implementation in its cpp
+ * file:
+ *
+ *   NS_IMPL_ISUPPORTS(nsFooBar, nsIFoo, nsIBar).
+ *
+ * Change this to
+ *
+ *   NS_IMPL_CLASSINFO(nsFooBar, nullptr, 0, NS_FOOBAR_CID)
+ *   NS_IMPL_ISUPPORTS_CI(nsFooBar, nsIFoo, nsIBar)
+ *
+ * If nsFooBar is threadsafe, change the 0 above to nsIClassInfo::THREADSAFE.
+ * If it's a singleton, use nsIClassInfo::SINGLETON.  The full list of flags is
+ * in nsIClassInfo.idl.
+ *
+ * The nullptr parameter is there so you can pass a function for converting
+ * from an XPCOM object to a scriptable helper.  Unless you're doing
+ * specialized JS work, you can probably leave this as nullptr.
+ *
+ * This file also defines the NS_IMPL_QUERY_INTERFACE_CI macro, which you can
+ * use to replace NS_IMPL_QUERY_INTERFACE, if you use that instead of
+ * NS_IMPL_ISUPPORTS.
+ *
+ * That's it!  The rest is gory details.
+ *
+ *
+ * Notice that nsFooBar didn't need to inherit from nsIClassInfo in order to
+ * "implement" it.  However, after adding these macros to nsFooBar, you you can
+ * QueryInterface an instance of nsFooBar to nsIClassInfo.  How can this be?
+ *
+ * The answer lies in the NS_IMPL_ISUPPORTS_CI macro.  It modifies nsFooBar's
+ * QueryInterface implementation such that, if we ask to QI to nsIClassInfo, it
+ * returns a singleton object associated with the class.  (That singleton is
+ * defined by NS_IMPL_CLASSINFO.)  So all nsFooBar instances will return the
+ * same object when QI'ed to nsIClassInfo.  (You can see this in
+ * NS_IMPL_QUERY_CLASSINFO below.)
+ *
+ * This hack breaks XPCOM's rules, since if you take an instance of nsFooBar,
+ * QI it to nsIClassInfo, and then try to QI to nsIFoo, that will fail.  On the
+ * upside, implementing nsIClassInfo doesn't add a vtable pointer to instances
+ * of your class.
+ *
+ * In principal, you can also implement nsIClassInfo by inheriting from the
+ * interface.  But some code expects that when it QI's an object to
+ * nsIClassInfo, it gets back a singleton which isn't attached to any
+ * particular object.  If a class were to implement nsIClassInfo through
+ * inheritance, that code might QI to nsIClassInfo and keep the resulting
+ * object alive, thinking it was only keeping alive the classinfo singleton,
+ * but in fact keeping a whole instance of the class alive.  See, e.g., bug
+ * 658632.
+ *
+ * Unless you specifically need to have a different nsIClassInfo instance for
+ * each instance of your class, you should probably just implement nsIClassInfo
+ * as a singleton.
+ */
+
+class GenericClassInfo : public nsIClassInfo
+{
+public:
+  struct ClassInfoData
+  {
+    // This function pointer uses NS_CALLBACK because it's always set to an
+    // NS_IMETHOD function, which uses __stdcall on Win32.
+    typedef NS_CALLBACK(GetInterfacesProc)(uint32_t* aCountP, nsIID*** aArray);
+    GetInterfacesProc getinterfaces;
+
+    // This function pointer doesn't use NS_CALLBACK because it's always set to
+    // a vanilla function.
+    typedef nsresult (*GetScriptableHelperProc)(nsIXPCScriptable** aHelper);
+    GetScriptableHelperProc getscriptablehelper;
+
+    uint32_t flags;
+    nsCID cid;
+  };
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSICLASSINFO
+
+  explicit GenericClassInfo(const ClassInfoData* aData) : mData(aData) {}
+
+private:
+  const ClassInfoData* mData;
+};
+
+#define NS_CLASSINFO_NAME(_class) g##_class##_classInfoGlobal
+#define NS_CI_INTERFACE_GETTER_NAME(_class) _class##_GetInterfacesHelper
+#define NS_DECL_CI_INTERFACE_GETTER(_class)                                   \
+  extern NS_IMETHODIMP NS_CI_INTERFACE_GETTER_NAME(_class)                    \
+     (uint32_t *, nsIID ***);
+
+#define NS_IMPL_CLASSINFO(_class, _getscriptablehelper, _flags, _cid)   \
+  NS_DECL_CI_INTERFACE_GETTER(_class)                                   \
+  static const GenericClassInfo::ClassInfoData k##_class##ClassInfoData = { \
+    NS_CI_INTERFACE_GETTER_NAME(_class),                                \
+    _getscriptablehelper,                                               \
+    _flags | nsIClassInfo::SINGLETON_CLASSINFO,                         \
+    _cid,                                                               \
+  };                                                                    \
+  mozilla::AlignedStorage2<GenericClassInfo> k##_class##ClassInfoDataPlace;   \
+  nsIClassInfo* NS_CLASSINFO_NAME(_class) = nullptr;
+
+#define NS_IMPL_QUERY_CLASSINFO(_class)                                       \
+  if ( aIID.Equals(NS_GET_IID(nsIClassInfo)) ) {                              \
+    if (!NS_CLASSINFO_NAME(_class))                                           \
+      NS_CLASSINFO_NAME(_class) = new (k##_class##ClassInfoDataPlace.addr())  \
+        GenericClassInfo(&k##_class##ClassInfoData);                          \
+    foundInterface = NS_CLASSINFO_NAME(_class);                               \
+  } else
+
+#define NS_CLASSINFO_HELPER_BEGIN(_class, _c)                                 \
+NS_IMETHODIMP                                                                 \
+NS_CI_INTERFACE_GETTER_NAME(_class)(uint32_t *count, nsIID ***array)          \
+{                                                                             \
+    *count = _c;                                                              \
+    *array = (nsIID **)moz_xmalloc(sizeof (nsIID *) * _c);                \
+    uint32_t i = 0;
+
+#define NS_CLASSINFO_HELPER_ENTRY(_interface)                                 \
+    (*array)[i++] = (nsIID*)nsMemory::Clone(&NS_GET_IID(_interface),          \
+                                            sizeof(nsIID));
+
+#define NS_CLASSINFO_HELPER_END                                               \
+    MOZ_ASSERT(i == *count, "Incorrent number of entries");                   \
+    return NS_OK;                                                             \
+}
+
+#define NS_IMPL_CI_INTERFACE_GETTER(aClass, ...)                              \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                             \
+  NS_CLASSINFO_HELPER_BEGIN(aClass,                                           \
+                            MOZ_PASTE_PREFIX_AND_ARG_COUNT(/* No prefix */,   \
+                                                           __VA_ARGS__))      \
+    MOZ_FOR_EACH(NS_CLASSINFO_HELPER_ENTRY, (), (__VA_ARGS__))                \
+  NS_CLASSINFO_HELPER_END
+
+#define NS_IMPL_QUERY_INTERFACE_CI(aClass, ...)                               \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                             \
+  NS_INTERFACE_MAP_BEGIN(aClass)                                              \
+    MOZ_FOR_EACH(NS_INTERFACE_MAP_ENTRY, (), (__VA_ARGS__))                   \
+    NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, MOZ_ARG_1(__VA_ARGS__))     \
+    NS_IMPL_QUERY_CLASSINFO(aClass)                                           \
+  NS_INTERFACE_MAP_END
+
+#define NS_IMPL_ISUPPORTS_CI(aClass, ...)                                     \
+  NS_IMPL_ADDREF(aClass)                                                      \
+  NS_IMPL_RELEASE(aClass)                                                     \
+  NS_IMPL_QUERY_INTERFACE_CI(aClass, __VA_ARGS__)                             \
+  NS_IMPL_CI_INTERFACE_GETTER(aClass, __VA_ARGS__)
+
+#endif // nsIClassInfoImpl_h__
diff --git a/xpcom/glue/nsID.cpp b/xpcom/glue/nsID.cpp
new file mode 100644
index 0000000000..0a73bf6c3f
--- /dev/null
+++ b/xpcom/glue/nsID.cpp
@@ -0,0 +1,133 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsID.h"
+#include "nsMemory.h"
+#include "mozilla/Sprintf.h"
+
+void nsID::Clear()
+{
+  m0 = 0;
+  m1 = 0;
+  m2 = 0;
+  for (int i = 0; i < 8; ++i) {
+    m3[i] = 0;
+  }
+}
+
+/**
+ * Multiplies the_int_var with 16 (0x10) and adds the value of the
+ * hexadecimal digit the_char. If it fails it returns false from
+ * the function it's used in.
+ */
+
+#define ADD_HEX_CHAR_TO_INT_OR_RETURN_FALSE(the_char, the_int_var) \
+    the_int_var = (the_int_var << 4) + the_char; \
+    if(the_char >= '0' && the_char <= '9') the_int_var -= '0'; \
+    else if(the_char >= 'a' && the_char <= 'f') the_int_var -= 'a'-10; \
+    else if(the_char >= 'A' && the_char <= 'F') the_int_var -= 'A'-10; \
+    else return false
+
+
+/**
+ * Parses number_of_chars characters from the char_pointer pointer and
+ * puts the number in the dest_variable. The pointer is moved to point
+ * at the first character after the parsed ones. If it fails it returns
+ * false from the function the macro is used in.
+ */
+
+#define PARSE_CHARS_TO_NUM(char_pointer, dest_variable, number_of_chars) \
+  do { int32_t _i=number_of_chars; \
+  dest_variable = 0; \
+  while(_i) { \
+    ADD_HEX_CHAR_TO_INT_OR_RETURN_FALSE(*char_pointer, dest_variable); \
+    char_pointer++; \
+    _i--; \
+  } } while(0)
+
+
+/**
+ * Parses a hyphen from the char_pointer string. If there is no hyphen there
+ * the function returns false from the function it's used in. The
+ * char_pointer is advanced one step.
+ */
+
+#define PARSE_HYPHEN(char_pointer) if (*(char_pointer++) != '-') return false
+
+/*
+ * Turns a {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} string into
+ * an nsID. It can also handle the old format without the { and }.
+ */
+
+bool
+nsID::Parse(const char* aIDStr)
+{
+  /* Optimized for speed */
+  if (!aIDStr) {
+    return false;
+  }
+
+  bool expectFormat1 = (aIDStr[0] == '{');
+  if (expectFormat1) {
+    ++aIDStr;
+  }
+
+  PARSE_CHARS_TO_NUM(aIDStr, m0, 8);
+  PARSE_HYPHEN(aIDStr);
+  PARSE_CHARS_TO_NUM(aIDStr, m1, 4);
+  PARSE_HYPHEN(aIDStr);
+  PARSE_CHARS_TO_NUM(aIDStr, m2, 4);
+  PARSE_HYPHEN(aIDStr);
+  int i;
+  for (i = 0; i < 2; ++i) {
+    PARSE_CHARS_TO_NUM(aIDStr, m3[i], 2);
+  }
+  PARSE_HYPHEN(aIDStr);
+  while (i < 8) {
+    PARSE_CHARS_TO_NUM(aIDStr, m3[i], 2);
+    i++;
+  }
+
+  return expectFormat1 ? *aIDStr == '}' : true;
+}
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+
+static const char gIDFormat[] =
+  "{%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x}";
+
+/*
+ * Returns an allocated string in {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
+ * format. The string is allocated with NS_Alloc and should be freed by
+ * the caller.
+ */
+
+char*
+nsID::ToString() const
+{
+  char* res = (char*)NS_Alloc(NSID_LENGTH);
+
+  if (res) {
+    snprintf(res, NSID_LENGTH, gIDFormat,
+             m0, (uint32_t)m1, (uint32_t)m2,
+             (uint32_t)m3[0], (uint32_t)m3[1], (uint32_t)m3[2],
+             (uint32_t)m3[3], (uint32_t)m3[4], (uint32_t)m3[5],
+             (uint32_t)m3[6], (uint32_t)m3[7]);
+  }
+  return res;
+}
+
+void
+nsID::ToProvidedString(char (&aDest)[NSID_LENGTH]) const
+{
+  SprintfLiteral(aDest, gIDFormat,
+                 m0, (uint32_t)m1, (uint32_t)m2,
+                 (uint32_t)m3[0], (uint32_t)m3[1], (uint32_t)m3[2],
+                 (uint32_t)m3[3], (uint32_t)m3[4], (uint32_t)m3[5],
+                 (uint32_t)m3[6], (uint32_t)m3[7]);
+}
+
+#endif // XPCOM_GLUE_AVOID_NSPR
diff --git a/xpcom/glue/nsID.h b/xpcom/glue/nsID.h
new file mode 100644
index 0000000000..c04007d4e9
--- /dev/null
+++ b/xpcom/glue/nsID.h
@@ -0,0 +1,179 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsID_h__
+#define nsID_h__
+
+#include <string.h>
+
+#include "nscore.h"
+
+#define NSID_LENGTH 39
+
+/**
+ * A "unique identifier". This is modeled after OSF DCE UUIDs.
+ */
+
+struct nsID
+{
+  /**
+   * @name Identifier values
+   */
+
+  //@{
+  uint32_t m0;
+  uint16_t m1;
+  uint16_t m2;
+  uint8_t m3[8];
+  //@}
+
+  /**
+   * @name Methods
+   */
+
+  //@{
+  /**
+   * Ensures everything is zeroed out.
+   */
+  void Clear();
+
+  /**
+   * Equivalency method. Compares this nsID with another.
+   * @return <b>true</b> if they are the same, <b>false</b> if not.
+   */
+
+  inline bool Equals(const nsID& aOther) const
+  {
+    // Unfortunately memcmp isn't faster than this.
+    return
+      (((uint32_t*)&m0)[0] == ((uint32_t*)&aOther.m0)[0]) &&
+      (((uint32_t*)&m0)[1] == ((uint32_t*)&aOther.m0)[1]) &&
+      (((uint32_t*)&m0)[2] == ((uint32_t*)&aOther.m0)[2]) &&
+      (((uint32_t*)&m0)[3] == ((uint32_t*)&aOther.m0)[3]);
+  }
+
+  inline bool operator==(const nsID& aOther) const
+  {
+    return Equals(aOther);
+  }
+
+  /**
+   * nsID Parsing method. Turns a {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
+   * string into an nsID
+   */
+  bool Parse(const char* aIDStr);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+  /**
+   * nsID string encoder. Returns an allocated string in
+   * {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} format. Caller should free string.
+   * YOU SHOULD ONLY USE THIS IF YOU CANNOT USE ToProvidedString() BELOW.
+   */
+  char* ToString() const;
+
+  /**
+   * nsID string encoder. Builds a string in
+   * {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} format, into a char[NSID_LENGTH]
+   * buffer provided by the caller (for instance, on the stack).
+   */
+  void ToProvidedString(char (&aDest)[NSID_LENGTH]) const;
+
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+  //@}
+};
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+/**
+ * A stack helper class to convert a nsID to a string.  Useful
+ * for printing nsIDs.  For example:
+ *   nsID aID = ...;
+ *   printf("%s", nsIDToCString(aID).get());
+ */
+class nsIDToCString
+{
+public:
+  explicit nsIDToCString(const nsID& aID)
+  {
+    aID.ToProvidedString(mStringBytes);
+  }
+
+  const char *get() const
+  {
+    return mStringBytes;
+  }
+
+protected:
+  char mStringBytes[NSID_LENGTH];
+};
+#endif
+
+/*
+ * Class IDs
+ */
+
+typedef nsID nsCID;
+
+// Define an CID
+#define NS_DEFINE_CID(_name, _cidspec) \
+  const nsCID _name = _cidspec
+
+#define NS_DEFINE_NAMED_CID(_name) \
+  static const nsCID k##_name = _name
+
+#define REFNSCID const nsCID&
+
+/**
+ * An "interface id" which can be used to uniquely identify a given
+ * interface.
+ */
+
+typedef nsID nsIID;
+
+/**
+ * A macro shorthand for <tt>const nsIID&<tt>
+ */
+
+#define REFNSIID const nsIID&
+
+/**
+ * Define an IID
+ * obsolete - do not use this macro
+ */
+
+#define NS_DEFINE_IID(_name, _iidspec) \
+  const nsIID _name = _iidspec
+
+/**
+ * A macro to build the static const IID accessor method. The Dummy
+ * template parameter only exists so that the kIID symbol will be linked
+ * properly (weak symbol on linux, gnu_linkonce on mac, multiple-definitions
+ * merged on windows). Dummy should always be instantiated as "void".
+ */
+
+#define NS_DECLARE_STATIC_IID_ACCESSOR(the_iid)                         \
+  template<typename T, typename U>                                      \
+  struct COMTypeInfo;
+
+#define NS_DEFINE_STATIC_IID_ACCESSOR(the_interface, the_iid)           \
+  template<typename T>                                                  \
+  struct the_interface::COMTypeInfo<the_interface, T> {                 \
+    static const nsIID kIID NS_HIDDEN;                                  \
+  };                                                                    \
+  template<typename T>                                                  \
+  const nsIID the_interface::COMTypeInfo<the_interface, T>::kIID NS_HIDDEN = the_iid;
+
+/**
+ * A macro to build the static const CID accessor method
+ */
+
+#define NS_DEFINE_STATIC_CID_ACCESSOR(the_cid) \
+  static const nsID& GetCID() {static const nsID cid = the_cid; return cid;}
+
+#define NS_GET_IID(T) (T::COMTypeInfo<T, void>::kIID)
+#define NS_GET_TEMPLATE_IID(T) (T::template COMTypeInfo<T, void>::kIID)
+
+#endif
diff --git a/xpcom/glue/nsIInterfaceRequestorUtils.cpp b/xpcom/glue/nsIInterfaceRequestorUtils.cpp
new file mode 100644
index 0000000000..8a2dfe3f85
--- /dev/null
+++ b/xpcom/glue/nsIInterfaceRequestorUtils.cpp
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+
+nsresult
+nsGetInterface::operator()(const nsIID& aIID, void** aInstancePtr) const
+{
+  nsresult status;
+
+  if (mSource) {
+    nsCOMPtr<nsIInterfaceRequestor> factoryPtr = do_QueryInterface(mSource);
+    if (factoryPtr) {
+      status = factoryPtr->GetInterface(aIID, aInstancePtr);
+    } else {
+      status = NS_ERROR_NO_INTERFACE;
+    }
+  } else {
+    status = NS_ERROR_NULL_POINTER;
+  }
+
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
diff --git a/xpcom/glue/nsIInterfaceRequestorUtils.h b/xpcom/glue/nsIInterfaceRequestorUtils.h
new file mode 100644
index 0000000000..718cf387b5
--- /dev/null
+++ b/xpcom/glue/nsIInterfaceRequestorUtils.h
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsInterfaceRequestorUtils_h
+#define __nsInterfaceRequestorUtils_h
+
+#include "nsCOMPtr.h"
+
+// a type-safe shortcut for calling the |GetInterface()| member function
+// T must inherit from nsIInterfaceRequestor, but the cast may be ambiguous.
+template<class T, class DestinationType>
+inline nsresult
+CallGetInterface(T* aSource, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aSource, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return aSource->GetInterface(NS_GET_TEMPLATE_IID(DestinationType),
+                               reinterpret_cast<void**>(aDestination));
+}
+
+class MOZ_STACK_CLASS nsGetInterface final : public nsCOMPtr_helper
+{
+public:
+  nsGetInterface(nsISupports* aSource, nsresult* aError)
+    : mSource(aSource)
+    , mErrorPtr(aError)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const
+    override;
+
+private:
+  nsISupports* MOZ_NON_OWNING_REF mSource;
+  nsresult* mErrorPtr;
+};
+
+inline const nsGetInterface
+do_GetInterface(nsISupports* aSource, nsresult* aError = 0)
+{
+  return nsGetInterface(aSource, aError);
+}
+
+#endif // __nsInterfaceRequestorUtils_h
+
diff --git a/xpcom/glue/nsINIParser.cpp b/xpcom/glue/nsINIParser.cpp
new file mode 100644
index 0000000000..53eae72929
--- /dev/null
+++ b/xpcom/glue/nsINIParser.cpp
@@ -0,0 +1,331 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Moz headers (alphabetical)
+#include "nsCRTGlue.h"
+#include "nsError.h"
+#include "nsIFile.h"
+#include "nsINIParser.h"
+#include "mozilla/FileUtils.h" // AutoFILE
+
+// System headers (alphabetical)
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef XP_WIN
+#include <windows.h>
+#endif
+
+#if defined(XP_WIN)
+#define READ_BINARYMODE L"rb"
+#else
+#define READ_BINARYMODE "r"
+#endif
+
+using namespace mozilla;
+
+#ifdef XP_WIN
+inline FILE*
+TS_tfopen(const char* aPath, const wchar_t* aMode)
+{
+  wchar_t wPath[MAX_PATH];
+  MultiByteToWideChar(CP_UTF8, 0, aPath, -1, wPath, MAX_PATH);
+  return _wfopen(wPath, aMode);
+}
+#else
+inline FILE*
+TS_tfopen(const char* aPath, const char* aMode)
+{
+  return fopen(aPath, aMode);
+}
+#endif
+
+// Stack based FILE wrapper to ensure that fclose is called, copied from
+// toolkit/mozapps/update/updater/readstrings.cpp
+
+class AutoFILE
+{
+public:
+  explicit AutoFILE(FILE* aFp = nullptr) : fp_(aFp) {}
+  ~AutoFILE()
+  {
+    if (fp_) {
+      fclose(fp_);
+    }
+  }
+  operator FILE*() { return fp_; }
+  FILE** operator&() { return &fp_; }
+  void operator=(FILE* aFp) { fp_ = aFp; }
+private:
+  FILE* fp_;
+};
+
+nsresult
+nsINIParser::Init(nsIFile* aFile)
+{
+  /* open the file. Don't use OpenANSIFileDesc, because you mustn't
+     pass FILE* across shared library boundaries, which may be using
+     different CRTs */
+
+  AutoFILE fd;
+
+#ifdef XP_WIN
+  nsAutoString path;
+  nsresult rv = aFile->GetPath(path);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  fd = _wfopen(path.get(), READ_BINARYMODE);
+#else
+  nsAutoCString path;
+  aFile->GetNativePath(path);
+
+  fd = fopen(path.get(), READ_BINARYMODE);
+#endif
+
+  if (!fd) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return InitFromFILE(fd);
+}
+
+nsresult
+nsINIParser::Init(const char* aPath)
+{
+  /* open the file */
+  AutoFILE fd(TS_tfopen(aPath, READ_BINARYMODE));
+  if (!fd) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return InitFromFILE(fd);
+}
+
+static const char kNL[] = "\r\n";
+static const char kEquals[] = "=";
+static const char kWhitespace[] = " \t";
+static const char kRBracket[] = "]";
+
+nsresult
+nsINIParser::InitFromFILE(FILE* aFd)
+{
+  /* get file size */
+  if (fseek(aFd, 0, SEEK_END) != 0) {
+    return NS_ERROR_FAILURE;
+  }
+
+  long flen = ftell(aFd);
+  /* zero-sized file, or an error */
+  if (flen <= 0) {
+    return NS_ERROR_FAILURE;
+  }
+
+  /* malloc an internal buf the size of the file */
+  mFileContents = MakeUnique<char[]>(flen + 2);
+  if (!mFileContents) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  /* read the file in one swoop */
+  if (fseek(aFd, 0, SEEK_SET) != 0) {
+    return NS_BASE_STREAM_OSERROR;
+  }
+
+  int rd = fread(mFileContents.get(), sizeof(char), flen, aFd);
+  if (rd != flen) {
+    return NS_BASE_STREAM_OSERROR;
+  }
+
+  // We write a UTF16 null so that the file is easier to convert to UTF8
+  mFileContents[flen] = mFileContents[flen + 1] = '\0';
+
+  char* buffer = &mFileContents[0];
+
+  if (flen >= 3 &&
+      mFileContents[0] == '\xEF' &&
+      mFileContents[1] == '\xBB' &&
+      mFileContents[2] == '\xBF') {
+    // Someone set us up the Utf-8 BOM
+    // This case is easy, since we assume that BOM-less
+    // files are Utf-8 anyway.  Just skip the BOM and process as usual.
+    buffer = &mFileContents[3];
+  }
+
+#ifdef XP_WIN
+  if (flen >= 2 &&
+      mFileContents[0] == '\xFF' &&
+      mFileContents[1] == '\xFE') {
+    // Someone set us up the Utf-16LE BOM
+    buffer = &mFileContents[2];
+    // Get the size required for our Utf8 buffer
+    flen = WideCharToMultiByte(CP_UTF8,
+                               0,
+                               reinterpret_cast<LPWSTR>(buffer),
+                               -1,
+                               nullptr,
+                               0,
+                               nullptr,
+                               nullptr);
+    if (flen == 0) {
+      return NS_ERROR_FAILURE;
+    }
+
+    UniquePtr<char[]> utf8Buffer(new char[flen]);
+    if (WideCharToMultiByte(CP_UTF8, 0, reinterpret_cast<LPWSTR>(buffer), -1,
+                            utf8Buffer.get(), flen, nullptr, nullptr) == 0) {
+      return NS_ERROR_FAILURE;
+    }
+    mFileContents = Move(utf8Buffer);
+    buffer = mFileContents.get();
+  }
+#endif
+
+  char* currSection = nullptr;
+
+  // outer loop tokenizes into lines
+  while (char* token = NS_strtok(kNL, &buffer)) {
+    if (token[0] == '#' || token[0] == ';') { // it's a comment
+      continue;
+    }
+
+    token = (char*)NS_strspnp(kWhitespace, token);
+    if (!*token) { // empty line
+      continue;
+    }
+
+    if (token[0] == '[') { // section header!
+      ++token;
+      currSection = token;
+
+      char* rb = NS_strtok(kRBracket, &token);
+      if (!rb || NS_strtok(kWhitespace, &token)) {
+        // there's either an unclosed [Section or a [Section]Moretext!
+        // we could frankly decide that this INI file is malformed right
+        // here and stop, but we won't... keep going, looking for
+        // a well-formed [section] to continue working with
+        currSection = nullptr;
+      }
+
+      continue;
+    }
+
+    if (!currSection) {
+      // If we haven't found a section header (or we found a malformed
+      // section header), don't bother parsing this line.
+      continue;
+    }
+
+    char* key = token;
+    char* e = NS_strtok(kEquals, &token);
+    if (!e || !token) {
+      continue;
+    }
+
+    INIValue* v;
+    if (!mSections.Get(currSection, &v)) {
+      v = new INIValue(key, token);
+      if (!v) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+
+      mSections.Put(currSection, v);
+      continue;
+    }
+
+    // Check whether this key has already been specified; overwrite
+    // if so, or append if not.
+    while (v) {
+      if (!strcmp(key, v->key)) {
+        v->value = token;
+        break;
+      }
+      if (!v->next) {
+        v->next = MakeUnique<INIValue>(key, token);
+        if (!v->next) {
+          return NS_ERROR_OUT_OF_MEMORY;
+        }
+        break;
+      }
+      v = v->next.get();
+    }
+    NS_ASSERTION(v, "v should never be null coming out of this loop");
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsINIParser::GetString(const char* aSection, const char* aKey,
+                       nsACString& aResult)
+{
+  INIValue* val;
+  mSections.Get(aSection, &val);
+
+  while (val) {
+    if (strcmp(val->key, aKey) == 0) {
+      aResult.Assign(val->value);
+      return NS_OK;
+    }
+
+    val = val->next.get();
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+nsresult
+nsINIParser::GetString(const char* aSection, const char* aKey,
+                       char* aResult, uint32_t aResultLen)
+{
+  INIValue* val;
+  mSections.Get(aSection, &val);
+
+  while (val) {
+    if (strcmp(val->key, aKey) == 0) {
+      strncpy(aResult, val->value, aResultLen);
+      aResult[aResultLen - 1] = '\0';
+      if (strlen(val->value) >= aResultLen) {
+        return NS_ERROR_LOSS_OF_SIGNIFICANT_DATA;
+      }
+
+      return NS_OK;
+    }
+
+    val = val->next.get();
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+nsresult
+nsINIParser::GetSections(INISectionCallback aCB, void* aClosure)
+{
+  for (auto iter = mSections.Iter(); !iter.Done(); iter.Next()) {
+    if (!aCB(iter.Key(), aClosure)) {
+      break;
+    }
+  }
+  return NS_OK;
+}
+
+nsresult
+nsINIParser::GetStrings(const char* aSection,
+                        INIStringCallback aCB, void* aClosure)
+{
+  INIValue* val;
+
+  for (mSections.Get(aSection, &val);
+       val;
+       val = val->next.get()) {
+
+    if (!aCB(val->key, val->value, aClosure)) {
+      return NS_OK;
+    }
+  }
+
+  return NS_OK;
+}
diff --git a/xpcom/glue/nsINIParser.h b/xpcom/glue/nsINIParser.h
new file mode 100644
index 0000000000..d0f553d49d
--- /dev/null
+++ b/xpcom/glue/nsINIParser.h
@@ -0,0 +1,118 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This file was shamelessly copied from mozilla/xpinstall/wizard/unix/src2
+
+#ifndef nsINIParser_h__
+#define nsINIParser_h__
+
+#ifdef MOZILLA_INTERNAL_API
+#define nsINIParser nsINIParser_internal
+#endif
+
+#include "nscore.h"
+#include "nsClassHashtable.h"
+#include "mozilla/UniquePtr.h"
+
+#include <stdio.h>
+
+class nsIFile;
+
+class nsINIParser
+{
+public:
+  nsINIParser() {}
+  ~nsINIParser() {}
+
+  /**
+   * Initialize the INIParser with a nsIFile. If this method fails, no
+   * other methods should be called. This method reads and parses the file,
+   * the class does not hold a file handle open. An instance must only be
+   * initialized once.
+   */
+  nsresult Init(nsIFile* aFile);
+
+  /**
+   * Initialize the INIParser with a file path. If this method fails, no
+   * other methods should be called. This method reads and parses the file,
+   * the class does not hold a file handle open. An instance must only
+   * be initialized once.
+   */
+  nsresult Init(const char* aPath);
+
+  /**
+   * Callback for GetSections
+   * @return false to stop enumeration, or true to continue.
+   */
+  typedef bool (*INISectionCallback)(const char* aSection, void* aClosure);
+
+  /**
+   * Enumerate the sections within the INI file.
+   */
+  nsresult GetSections(INISectionCallback aCB, void* aClosure);
+
+  /**
+   * Callback for GetStrings
+   * @return false to stop enumeration, or true to continue
+   */
+  typedef bool (*INIStringCallback)(const char* aString, const char* aValue,
+                                    void* aClosure);
+
+  /**
+   * Enumerate the strings within a section. If the section does
+   * not exist, this function will silently return.
+   */
+  nsresult GetStrings(const char* aSection,
+                      INIStringCallback aCB, void* aClosure);
+
+  /**
+   * Get the value of the specified key in the specified section
+   * of the INI file represented by this instance.
+   *
+   * @param aSection      section name
+   * @param aKey          key name
+   * @param aResult       the value found
+   * @throws NS_ERROR_FAILURE if the specified section/key could not be
+   *                          found.
+   */
+  nsresult GetString(const char* aSection, const char* aKey,
+                     nsACString& aResult);
+
+  /**
+   * Alternate signature of GetString that uses a pre-allocated buffer
+   * instead of a nsACString (for use in the standalone glue before
+   * the glue is initialized).
+   *
+   * @throws NS_ERROR_LOSS_OF_SIGNIFICANT_DATA if the aResult buffer is not
+   *         large enough for the data. aResult will be filled with as
+   *         much data as possible.
+   *
+   * @see GetString [1]
+   */
+  nsresult GetString(const char* aSection, const char* aKey,
+                     char* aResult, uint32_t aResultLen);
+
+private:
+  struct INIValue
+  {
+    INIValue(const char* aKey, const char* aValue)
+      : key(aKey)
+      , value(aValue)
+    {
+    }
+
+    const char* key;
+    const char* value;
+    mozilla::UniquePtr<INIValue> next;
+  };
+
+  nsClassHashtable<nsDepCharHashKey, INIValue> mSections;
+  mozilla::UniquePtr<char[]> mFileContents;
+
+  nsresult InitFromFILE(FILE* aFd);
+};
+
+#endif /* nsINIParser_h__ */
diff --git a/xpcom/glue/nsISupportsImpl.cpp b/xpcom/glue/nsISupportsImpl.cpp
new file mode 100644
index 0000000000..c60c0bfa73
--- /dev/null
+++ b/xpcom/glue/nsISupportsImpl.cpp
@@ -0,0 +1,27 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupportsImpl.h"
+
+nsresult NS_FASTCALL
+NS_TableDrivenQI(void* aThis, REFNSIID aIID, void** aInstancePtr,
+                 const QITableEntry* aEntries)
+{
+  do {
+    if (aIID.Equals(*aEntries->iid)) {
+      nsISupports* r = reinterpret_cast<nsISupports*>(
+        reinterpret_cast<char*>(aThis) + aEntries->offset);
+      NS_ADDREF(r);
+      *aInstancePtr = r;
+      return NS_OK;
+    }
+
+    ++aEntries;
+  } while (aEntries->iid);
+
+  *aInstancePtr = nullptr;
+  return NS_ERROR_NO_INTERFACE;
+}
diff --git a/xpcom/glue/nsISupportsImpl.h b/xpcom/glue/nsISupportsImpl.h
new file mode 100644
index 0000000000..26db3c525d
--- /dev/null
+++ b/xpcom/glue/nsISupportsImpl.h
@@ -0,0 +1,1090 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsISupports.h"
+
+
+#ifndef nsISupportsImpl_h__
+#define nsISupportsImpl_h__
+
+#include "nscore.h"
+#include "nsISupportsBase.h"
+#include "nsISupportsUtils.h"
+
+
+#if !defined(XPCOM_GLUE_AVOID_NSPR)
+#include "prthread.h" /* needed for thread-safety checks */
+#endif // !XPCOM_GLUE_AVOID_NSPR
+
+#include "nsDebug.h"
+#include "nsXPCOM.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Compiler.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MacroArgs.h"
+#include "mozilla/MacroForEach.h"
+#include "mozilla/TypeTraits.h"
+
+#define MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(X) \
+  static_assert(!mozilla::IsDestructible<X>::value, \
+                "Reference-counted class " #X " should not have a public destructor. " \
+                "Make this class's destructor non-public");
+
+inline nsISupports*
+ToSupports(nsISupports* aSupports)
+{
+  return aSupports;
+}
+
+inline nsISupports*
+ToCanonicalSupports(nsISupports* aSupports)
+{
+  return nullptr;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Macros to help detect thread-safety:
+
+#ifdef MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED
+
+class nsAutoOwningThread
+{
+public:
+  nsAutoOwningThread() { mThread = PR_GetCurrentThread(); }
+  void* GetThread() const { return mThread; }
+
+private:
+  void* mThread;
+};
+
+#define NS_DECL_OWNINGTHREAD            nsAutoOwningThread _mOwningThread;
+#define NS_ASSERT_OWNINGTHREAD_AGGREGATE(agg, _class) \
+  NS_CheckThreadSafe(agg->_mOwningThread.GetThread(), #_class " not thread-safe")
+#define NS_ASSERT_OWNINGTHREAD(_class) NS_ASSERT_OWNINGTHREAD_AGGREGATE(this, _class)
+#else // !DEBUG && !(NIGHTLY_BUILD && !MOZ_PROFILING)
+
+#define NS_DECL_OWNINGTHREAD            /* nothing */
+#define NS_ASSERT_OWNINGTHREAD_AGGREGATE(agg, _class) ((void)0)
+#define NS_ASSERT_OWNINGTHREAD(_class)  ((void)0)
+
+#endif // DEBUG || (NIGHTLY_BUILD && !MOZ_PROFILING)
+
+
+// Macros for reference-count and constructor logging
+
+#if defined(NS_BUILD_REFCNT_LOGGING)
+
+#define NS_LOG_ADDREF(_p, _rc, _type, _size) \
+  NS_LogAddRef((_p), (_rc), (_type), (uint32_t) (_size))
+
+#define NS_LOG_RELEASE(_p, _rc, _type) \
+  NS_LogRelease((_p), (_rc), (_type))
+
+#include "mozilla/TypeTraits.h"
+#define MOZ_ASSERT_CLASSNAME(_type)                         \
+  static_assert(mozilla::IsClass<_type>::value,             \
+                "Token '" #_type "' is not a class type.")
+
+// Note that the following constructor/destructor logging macros are redundant
+// for refcounted objects that log via the NS_LOG_ADDREF/NS_LOG_RELEASE macros.
+// Refcount logging is preferred.
+#define MOZ_COUNT_CTOR(_type)                                 \
+do {                                                          \
+  MOZ_ASSERT_CLASSNAME(_type);                                \
+  NS_LogCtor((void*)this, #_type, sizeof(*this));             \
+} while (0)
+
+#define MOZ_COUNT_CTOR_INHERITED(_type, _base)                    \
+do {                                                              \
+  MOZ_ASSERT_CLASSNAME(_type);                                    \
+  MOZ_ASSERT_CLASSNAME(_base);                                    \
+  NS_LogCtor((void*)this, #_type, sizeof(*this) - sizeof(_base)); \
+} while (0)
+
+#define MOZ_LOG_CTOR(_ptr, _name, _size) \
+do {                                     \
+  NS_LogCtor((void*)_ptr, _name, _size); \
+} while (0)
+
+#define MOZ_COUNT_DTOR(_type)                                 \
+do {                                                          \
+  MOZ_ASSERT_CLASSNAME(_type);                                \
+  NS_LogDtor((void*)this, #_type, sizeof(*this));             \
+} while (0)
+
+#define MOZ_COUNT_DTOR_INHERITED(_type, _base)                    \
+do {                                                              \
+  MOZ_ASSERT_CLASSNAME(_type);                                    \
+  MOZ_ASSERT_CLASSNAME(_base);                                    \
+  NS_LogDtor((void*)this, #_type, sizeof(*this) - sizeof(_base)); \
+} while (0)
+
+#define MOZ_LOG_DTOR(_ptr, _name, _size) \
+do {                                     \
+  NS_LogDtor((void*)_ptr, _name, _size); \
+} while (0)
+
+/* nsCOMPtr.h allows these macros to be defined by clients
+ * These logging functions require dynamic_cast<void*>, so they don't
+ * do anything useful if we don't have dynamic_cast<void*>.
+ * Note: The explicit comparison to nullptr is needed to avoid warnings
+ *       when _p is a nullptr itself. */
+#define NSCAP_LOG_ASSIGNMENT(_c, _p)                                \
+  if (_p != nullptr)                                                \
+    NS_LogCOMPtrAddRef((_c),static_cast<nsISupports*>(_p))
+
+#define NSCAP_LOG_RELEASE(_c, _p)                                   \
+  if (_p)                                                           \
+    NS_LogCOMPtrRelease((_c), static_cast<nsISupports*>(_p))
+
+#else /* !NS_BUILD_REFCNT_LOGGING */
+
+#define NS_LOG_ADDREF(_p, _rc, _type, _size)
+#define NS_LOG_RELEASE(_p, _rc, _type)
+#define MOZ_COUNT_CTOR(_type)
+#define MOZ_COUNT_CTOR_INHERITED(_type, _base)
+#define MOZ_LOG_CTOR(_ptr, _name, _size)
+#define MOZ_COUNT_DTOR(_type)
+#define MOZ_COUNT_DTOR_INHERITED(_type, _base)
+#define MOZ_LOG_DTOR(_ptr, _name, _size)
+
+#endif /* NS_BUILD_REFCNT_LOGGING */
+
+
+// Support for ISupports classes which interact with cycle collector.
+
+#define NS_NUMBER_OF_FLAGS_IN_REFCNT 2
+#define NS_IN_PURPLE_BUFFER (1 << 0)
+#define NS_IS_PURPLE (1 << 1)
+#define NS_REFCOUNT_CHANGE (1 << NS_NUMBER_OF_FLAGS_IN_REFCNT)
+#define NS_REFCOUNT_VALUE(_val) (_val >> NS_NUMBER_OF_FLAGS_IN_REFCNT)
+
+class nsCycleCollectingAutoRefCnt
+{
+public:
+  nsCycleCollectingAutoRefCnt() : mRefCntAndFlags(0) {}
+
+  explicit nsCycleCollectingAutoRefCnt(uintptr_t aValue)
+    : mRefCntAndFlags(aValue << NS_NUMBER_OF_FLAGS_IN_REFCNT)
+  {
+  }
+
+  nsCycleCollectingAutoRefCnt(const nsCycleCollectingAutoRefCnt&) = delete;
+  void operator=(const nsCycleCollectingAutoRefCnt&) = delete;
+
+  MOZ_ALWAYS_INLINE uintptr_t incr(nsISupports* aOwner)
+  {
+    return incr(aOwner, nullptr);
+  }
+
+  MOZ_ALWAYS_INLINE uintptr_t incr(void* aOwner,
+                                   nsCycleCollectionParticipant* aCp)
+  {
+    mRefCntAndFlags += NS_REFCOUNT_CHANGE;
+    mRefCntAndFlags &= ~NS_IS_PURPLE;
+    // For incremental cycle collection, use the purple buffer to track objects
+    // that have been AddRef'd.
+    if (!IsInPurpleBuffer()) {
+      mRefCntAndFlags |= NS_IN_PURPLE_BUFFER;
+      // Refcount isn't zero, so Suspect won't delete anything.
+      MOZ_ASSERT(get() > 0);
+      NS_CycleCollectorSuspect3(aOwner, aCp, this, nullptr);
+    }
+    return NS_REFCOUNT_VALUE(mRefCntAndFlags);
+  }
+
+  MOZ_ALWAYS_INLINE void stabilizeForDeletion()
+  {
+    // Set refcnt to 1 and mark us to be in the purple buffer.
+    // This way decr won't call suspect again.
+    mRefCntAndFlags = NS_REFCOUNT_CHANGE | NS_IN_PURPLE_BUFFER;
+  }
+
+  MOZ_ALWAYS_INLINE uintptr_t decr(nsISupports* aOwner,
+                                   bool* aShouldDelete = nullptr)
+  {
+    return decr(aOwner, nullptr, aShouldDelete);
+  }
+
+  MOZ_ALWAYS_INLINE uintptr_t decr(void* aOwner,
+                                   nsCycleCollectionParticipant* aCp,
+                                   bool* aShouldDelete = nullptr)
+  {
+    MOZ_ASSERT(get() > 0);
+    if (!IsInPurpleBuffer()) {
+      mRefCntAndFlags -= NS_REFCOUNT_CHANGE;
+      mRefCntAndFlags |= (NS_IN_PURPLE_BUFFER | NS_IS_PURPLE);
+      uintptr_t retval = NS_REFCOUNT_VALUE(mRefCntAndFlags);
+      // Suspect may delete 'aOwner' and 'this'!
+      NS_CycleCollectorSuspect3(aOwner, aCp, this, aShouldDelete);
+      return retval;
+    }
+    mRefCntAndFlags -= NS_REFCOUNT_CHANGE;
+    mRefCntAndFlags |= (NS_IN_PURPLE_BUFFER | NS_IS_PURPLE);
+    return NS_REFCOUNT_VALUE(mRefCntAndFlags);
+  }
+
+  MOZ_ALWAYS_INLINE void RemovePurple()
+  {
+    MOZ_ASSERT(IsPurple(), "must be purple");
+    mRefCntAndFlags &= ~NS_IS_PURPLE;
+  }
+
+  MOZ_ALWAYS_INLINE void RemoveFromPurpleBuffer()
+  {
+    MOZ_ASSERT(IsInPurpleBuffer());
+    mRefCntAndFlags &= ~(NS_IS_PURPLE | NS_IN_PURPLE_BUFFER);
+  }
+
+  MOZ_ALWAYS_INLINE bool IsPurple() const
+  {
+    return !!(mRefCntAndFlags & NS_IS_PURPLE);
+  }
+
+  MOZ_ALWAYS_INLINE bool IsInPurpleBuffer() const
+  {
+    return !!(mRefCntAndFlags & NS_IN_PURPLE_BUFFER);
+  }
+
+  MOZ_ALWAYS_INLINE nsrefcnt get() const
+  {
+    return NS_REFCOUNT_VALUE(mRefCntAndFlags);
+  }
+
+  MOZ_ALWAYS_INLINE operator nsrefcnt() const
+  {
+    return get();
+  }
+
+private:
+  uintptr_t mRefCntAndFlags;
+};
+
+class nsAutoRefCnt
+{
+public:
+  nsAutoRefCnt() : mValue(0) {}
+  explicit nsAutoRefCnt(nsrefcnt aValue) : mValue(aValue) {}
+
+  nsAutoRefCnt(const nsAutoRefCnt&) = delete;
+  void operator=(const nsAutoRefCnt&) = delete;
+
+  // only support prefix increment/decrement
+  nsrefcnt operator++() { return ++mValue; }
+  nsrefcnt operator--() { return --mValue; }
+
+  nsrefcnt operator=(nsrefcnt aValue) { return (mValue = aValue); }
+  operator nsrefcnt() const { return mValue; }
+  nsrefcnt get() const { return mValue; }
+
+  static const bool isThreadSafe = false;
+private:
+  nsrefcnt operator++(int) = delete;
+  nsrefcnt operator--(int) = delete;
+  nsrefcnt mValue;
+};
+
+namespace mozilla {
+class ThreadSafeAutoRefCnt
+{
+public:
+  ThreadSafeAutoRefCnt() : mValue(0) {}
+  explicit ThreadSafeAutoRefCnt(nsrefcnt aValue) : mValue(aValue) {}
+
+  ThreadSafeAutoRefCnt(const ThreadSafeAutoRefCnt&) = delete;
+  void operator=(const ThreadSafeAutoRefCnt&) = delete;
+
+  // only support prefix increment/decrement
+  MOZ_ALWAYS_INLINE nsrefcnt operator++() { return ++mValue; }
+  MOZ_ALWAYS_INLINE nsrefcnt operator--() { return --mValue; }
+
+  MOZ_ALWAYS_INLINE nsrefcnt operator=(nsrefcnt aValue)
+  {
+    return (mValue = aValue);
+  }
+  MOZ_ALWAYS_INLINE operator nsrefcnt() const { return mValue; }
+  MOZ_ALWAYS_INLINE nsrefcnt get() const { return mValue; }
+
+  static const bool isThreadSafe = true;
+private:
+  nsrefcnt operator++(int) = delete;
+  nsrefcnt operator--(int) = delete;
+  // In theory, RelaseAcquire consistency (but no weaker) is sufficient for
+  // the counter. Making it weaker could speed up builds on ARM (but not x86),
+  // but could break pre-existing code that assumes sequential consistency.
+  Atomic<nsrefcnt> mValue;
+};
+} // namespace mozilla
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ * Declare the reference count variable and the implementations of the
+ * AddRef and QueryInterface methods.
+ */
+
+#define NS_DECL_ISUPPORTS                                                     \
+public:                                                                       \
+  NS_IMETHOD QueryInterface(REFNSIID aIID,                                    \
+                            void** aInstancePtr) override;                    \
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;                 \
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) override;                \
+  typedef mozilla::FalseType HasThreadSafeRefCnt;                             \
+protected:                                                                    \
+  nsAutoRefCnt mRefCnt;                                                       \
+  NS_DECL_OWNINGTHREAD                                                        \
+public:
+
+#define NS_DECL_THREADSAFE_ISUPPORTS                                          \
+public:                                                                       \
+  NS_IMETHOD QueryInterface(REFNSIID aIID,                                    \
+                            void** aInstancePtr) override;                    \
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;                 \
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) override;                \
+  typedef mozilla::TrueType HasThreadSafeRefCnt;                              \
+protected:                                                                    \
+  ::mozilla::ThreadSafeAutoRefCnt mRefCnt;                                    \
+  NS_DECL_OWNINGTHREAD                                                        \
+public:
+
+#define NS_DECL_CYCLE_COLLECTING_ISUPPORTS                                    \
+public:                                                                       \
+  NS_IMETHOD QueryInterface(REFNSIID aIID,                                    \
+                            void** aInstancePtr) override;                    \
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;                 \
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) override;                \
+  NS_IMETHOD_(void) DeleteCycleCollectable(void);                             \
+  typedef mozilla::FalseType HasThreadSafeRefCnt;                             \
+protected:                                                                    \
+  nsCycleCollectingAutoRefCnt mRefCnt;                                        \
+  NS_DECL_OWNINGTHREAD                                                        \
+public:
+
+
+///////////////////////////////////////////////////////////////////////////////
+
+/*
+ * Implementation of AddRef and Release for non-nsISupports (ie "native")
+ * cycle-collected classes that use the purple buffer to avoid leaks.
+ */
+
+#define NS_IMPL_CC_NATIVE_ADDREF_BODY(_class)                                 \
+    MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                \
+    MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                      \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+    nsrefcnt count =                                                          \
+      mRefCnt.incr(static_cast<void*>(this),                                  \
+                   _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()); \
+    NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                       \
+    return count;
+
+#define NS_IMPL_CC_NATIVE_RELEASE_BODY(_class)                                \
+    MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                          \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+    nsrefcnt count =                                                          \
+      mRefCnt.decr(static_cast<void*>(this),                                  \
+                   _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()); \
+    NS_LOG_RELEASE(this, count, #_class);                                     \
+    return count;
+
+#define NS_IMPL_CYCLE_COLLECTING_NATIVE_ADDREF(_class)                        \
+NS_METHOD_(MozExternalRefCountType) _class::AddRef(void)                      \
+{                                                                             \
+  NS_IMPL_CC_NATIVE_ADDREF_BODY(_class)                                       \
+}
+
+#define NS_IMPL_CYCLE_COLLECTING_NATIVE_RELEASE_WITH_LAST_RELEASE(_class, _last) \
+NS_METHOD_(MozExternalRefCountType) _class::Release(void)                        \
+{                                                                                \
+    MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                             \
+    NS_ASSERT_OWNINGTHREAD(_class);                                              \
+    bool shouldDelete = false;                                                   \
+    nsrefcnt count =                                                             \
+      mRefCnt.decr(static_cast<void*>(this),                                     \
+                   _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant(),     \
+                   &shouldDelete);                                               \
+    NS_LOG_RELEASE(this, count, #_class);                                        \
+    if (count == 0) {                                                            \
+        mRefCnt.incr(static_cast<void*>(this),                                   \
+                     _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant());  \
+        _last;                                                                   \
+        mRefCnt.decr(static_cast<void*>(this),                                   \
+                     _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant());  \
+        if (shouldDelete) {                                                      \
+            mRefCnt.stabilizeForDeletion();                                      \
+            DeleteCycleCollectable();                                            \
+        }                                                                        \
+    }                                                                            \
+    return count;                                                                \
+}
+
+#define NS_IMPL_CYCLE_COLLECTING_NATIVE_RELEASE(_class)                       \
+NS_METHOD_(MozExternalRefCountType) _class::Release(void)                     \
+{                                                                             \
+  NS_IMPL_CC_NATIVE_RELEASE_BODY(_class)                                      \
+}
+
+#define NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(_class)            \
+public:                                                                       \
+  NS_METHOD_(MozExternalRefCountType) AddRef(void) {                          \
+    NS_IMPL_CC_NATIVE_ADDREF_BODY(_class)                                     \
+  }                                                                           \
+  NS_METHOD_(MozExternalRefCountType) Release(void) {                         \
+    NS_IMPL_CC_NATIVE_RELEASE_BODY(_class)                                    \
+  }                                                                           \
+  typedef mozilla::FalseType HasThreadSafeRefCnt;                             \
+protected:                                                                    \
+  nsCycleCollectingAutoRefCnt mRefCnt;                                        \
+  NS_DECL_OWNINGTHREAD                                                        \
+public:
+
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ * Use this macro to declare and implement the AddRef & Release methods for a
+ * given non-XPCOM <i>_class</i>.
+ *
+ * @param _class The name of the class implementing the method
+ * @param _destroy A statement that is executed when the object's
+ *   refcount drops to zero.
+ * @param optional override Mark the AddRef & Release methods as overrides.
+ */
+#define NS_INLINE_DECL_REFCOUNTING_WITH_DESTROY(_class, _destroy, ...)        \
+public:                                                                       \
+  NS_METHOD_(MozExternalRefCountType) AddRef(void) __VA_ARGS__ {              \
+    MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                \
+    MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                      \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+    ++mRefCnt;                                                                \
+    NS_LOG_ADDREF(this, mRefCnt, #_class, sizeof(*this));                     \
+    return mRefCnt;                                                           \
+  }                                                                           \
+  NS_METHOD_(MozExternalRefCountType) Release(void) __VA_ARGS__ {             \
+    MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                          \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+    --mRefCnt;                                                                \
+    NS_LOG_RELEASE(this, mRefCnt, #_class);                                   \
+    if (mRefCnt == 0) {                                                       \
+      mRefCnt = 1; /* stabilize */                                            \
+      _destroy;                                                               \
+      return 0;                                                               \
+    }                                                                         \
+    return mRefCnt;                                                           \
+  }                                                                           \
+  typedef mozilla::FalseType HasThreadSafeRefCnt;                             \
+protected:                                                                    \
+  nsAutoRefCnt mRefCnt;                                                       \
+  NS_DECL_OWNINGTHREAD                                                        \
+public:
+
+/**
+ * Use this macro to declare and implement the AddRef & Release methods for a
+ * given non-XPCOM <i>_class</i>.
+ *
+ * @param _class The name of the class implementing the method
+ * @param optional override Mark the AddRef & Release methods as overrides.
+ */
+#define NS_INLINE_DECL_REFCOUNTING(_class, ...)                               \
+  NS_INLINE_DECL_REFCOUNTING_WITH_DESTROY(_class, delete(this), __VA_ARGS__)
+
+#define NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, _decl, ...)        \
+public:                                                                       \
+  _decl(MozExternalRefCountType) AddRef(void) __VA_ARGS__ {                   \
+    MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                \
+    MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                      \
+    nsrefcnt count = ++mRefCnt;                                               \
+    NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                       \
+    return (nsrefcnt) count;                                                  \
+  }                                                                           \
+  _decl(MozExternalRefCountType) Release(void) __VA_ARGS__ {                  \
+    MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                          \
+    nsrefcnt count = --mRefCnt;                                               \
+    NS_LOG_RELEASE(this, count, #_class);                                     \
+    if (count == 0) {                                                         \
+      delete (this);                                                          \
+      return 0;                                                               \
+    }                                                                         \
+    return count;                                                             \
+  }                                                                           \
+  typedef mozilla::TrueType HasThreadSafeRefCnt;                              \
+protected:                                                                    \
+  ::mozilla::ThreadSafeAutoRefCnt mRefCnt;                                    \
+public:
+
+/**
+ * Use this macro to declare and implement the AddRef & Release methods for a
+ * given non-XPCOM <i>_class</i> in a threadsafe manner.
+ *
+ * DOES NOT DO REFCOUNT STABILIZATION!
+ *
+ * @param _class The name of the class implementing the method
+ */
+#define NS_INLINE_DECL_THREADSAFE_REFCOUNTING(_class, ...)                    \
+NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, NS_METHOD_, __VA_ARGS__)
+
+/**
+ * Like NS_INLINE_DECL_THREADSAFE_REFCOUNTING with AddRef & Release declared
+ * virtual.
+ */
+#define NS_INLINE_DECL_THREADSAFE_VIRTUAL_REFCOUNTING(_class, ...)            \
+NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, NS_IMETHOD_, __VA_ARGS__)
+
+/**
+ * Use this macro to implement the AddRef method for a given <i>_class</i>
+ * @param _class The name of the class implementing the method
+ */
+#define NS_IMPL_ADDREF(_class)                                                \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void)                  \
+{                                                                             \
+  MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                  \
+  MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                        \
+  if (!mRefCnt.isThreadSafe)                                                  \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+  nsrefcnt count = ++mRefCnt;                                                 \
+  NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                         \
+  return count;                                                               \
+}
+
+/**
+ * Use this macro to implement the AddRef method for a given <i>_class</i>
+ * implemented as a wholly owned aggregated object intended to implement
+ * interface(s) for its owner
+ * @param _class The name of the class implementing the method
+ * @param _aggregator the owning/containing object
+ */
+#define NS_IMPL_ADDREF_USING_AGGREGATOR(_class, _aggregator)                  \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void)                  \
+{                                                                             \
+  MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                  \
+  NS_PRECONDITION(_aggregator, "null aggregator");                            \
+  return (_aggregator)->AddRef();                                             \
+}
+
+/**
+ * Use this macro to implement the Release method for a given
+ * <i>_class</i>.
+ * @param _class The name of the class implementing the method
+ * @param _destroy A statement that is executed when the object's
+ *   refcount drops to zero.
+ *
+ * For example,
+ *
+ *   NS_IMPL_RELEASE_WITH_DESTROY(Foo, Destroy(this))
+ *
+ * will cause
+ *
+ *   Destroy(this);
+ *
+ * to be invoked when the object's refcount drops to zero. This
+ * allows for arbitrary teardown activity to occur (e.g., deallocation
+ * of object allocated with placement new).
+ */
+#define NS_IMPL_RELEASE_WITH_DESTROY(_class, _destroy)                        \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void)                 \
+{                                                                             \
+  MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                            \
+  if (!mRefCnt.isThreadSafe)                                                  \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+  nsrefcnt count = --mRefCnt;                                                 \
+  NS_LOG_RELEASE(this, count, #_class);                                       \
+  if (count == 0) {                                                           \
+    mRefCnt = 1; /* stabilize */                                              \
+    _destroy;                                                                 \
+    return 0;                                                                 \
+  }                                                                           \
+  return count;                                                               \
+}
+
+/**
+ * Use this macro to implement the Release method for a given <i>_class</i>
+ * @param _class The name of the class implementing the method
+ *
+ * A note on the 'stabilization' of the refcnt to one. At that point,
+ * the object's refcount will have gone to zero. The object's
+ * destructor may trigger code that attempts to QueryInterface() and
+ * Release() 'this' again. Doing so will temporarily increment and
+ * decrement the refcount. (Only a logic error would make one try to
+ * keep a permanent hold on 'this'.)  To prevent re-entering the
+ * destructor, we make sure that no balanced refcounting can return
+ * the refcount to |0|.
+ */
+#define NS_IMPL_RELEASE(_class) \
+  NS_IMPL_RELEASE_WITH_DESTROY(_class, delete (this))
+
+/**
+ * Use this macro to implement the Release method for a given <i>_class</i>
+ * implemented as a wholly owned aggregated object intended to implement
+ * interface(s) for its owner
+ * @param _class The name of the class implementing the method
+ * @param _aggregator the owning/containing object
+ */
+#define NS_IMPL_RELEASE_USING_AGGREGATOR(_class, _aggregator)                 \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void)                 \
+{                                                                             \
+  NS_PRECONDITION(_aggregator, "null aggregator");                            \
+  return (_aggregator)->Release();                                            \
+}
+
+
+#define NS_IMPL_CYCLE_COLLECTING_ADDREF(_class)                               \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void)                  \
+{                                                                             \
+  MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                  \
+  MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                        \
+  NS_ASSERT_OWNINGTHREAD(_class);                                             \
+  nsISupports *base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this);    \
+  nsrefcnt count = mRefCnt.incr(base);                                        \
+  NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                         \
+  return count;                                                               \
+}
+
+#define NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_DESTROY(_class, _destroy)       \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void)                 \
+{                                                                             \
+  MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                            \
+  NS_ASSERT_OWNINGTHREAD(_class);                                             \
+  nsISupports *base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this);    \
+  nsrefcnt count = mRefCnt.decr(base);                                        \
+  NS_LOG_RELEASE(this, count, #_class);                                       \
+  return count;                                                               \
+}                                                                             \
+NS_IMETHODIMP_(void) _class::DeleteCycleCollectable(void)                     \
+{                                                                             \
+  _destroy;                                                                   \
+}
+
+#define NS_IMPL_CYCLE_COLLECTING_RELEASE(_class)                              \
+  NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_DESTROY(_class, delete (this))
+
+// _LAST_RELEASE can be useful when certain resources should be released
+// as soon as we know the object will be deleted.
+#define NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_LAST_RELEASE(_class, _last)     \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void)                 \
+{                                                                             \
+  MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                            \
+  NS_ASSERT_OWNINGTHREAD(_class);                                             \
+  bool shouldDelete = false;                                                  \
+  nsISupports *base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this);    \
+  nsrefcnt count = mRefCnt.decr(base, &shouldDelete);                         \
+  NS_LOG_RELEASE(this, count, #_class);                                       \
+  if (count == 0) {                                                           \
+      mRefCnt.incr(base);                                                     \
+      _last;                                                                  \
+      mRefCnt.decr(base);                                                     \
+      if (shouldDelete) {                                                     \
+          mRefCnt.stabilizeForDeletion();                                     \
+          DeleteCycleCollectable();                                           \
+      }                                                                       \
+  }                                                                           \
+  return count;                                                               \
+}                                                                             \
+NS_IMETHODIMP_(void) _class::DeleteCycleCollectable(void)                     \
+{                                                                             \
+  delete this;                                                                \
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ * There are two ways of implementing QueryInterface, and we use both:
+ *
+ * Table-driven QueryInterface uses a static table of IID->offset mappings
+ * and a shared helper function. Using it tends to reduce codesize and improve
+ * runtime performance (due to processor cache hits).
+ *
+ * Macro-driven QueryInterface generates a QueryInterface function directly
+ * using common macros. This is necessary if special QueryInterface features
+ * are being used (such as tearoffs and conditional interfaces).
+ *
+ * These methods can be combined into a table-driven function call followed
+ * by custom code for tearoffs and conditionals.
+ */
+
+struct QITableEntry
+{
+  const nsIID* iid;     // null indicates end of the QITableEntry array
+  int32_t   offset;
+};
+
+nsresult NS_FASTCALL
+NS_TableDrivenQI(void* aThis, REFNSIID aIID,
+                 void** aInstancePtr, const QITableEntry* aEntries);
+
+/**
+ * Implement table-driven queryinterface
+ */
+
+#define NS_INTERFACE_TABLE_HEAD(_class)                                       \
+NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr)      \
+{                                                                             \
+  NS_ASSERTION(aInstancePtr,                                                  \
+               "QueryInterface requires a non-NULL destination!");            \
+  nsresult rv = NS_ERROR_FAILURE;
+
+#define NS_INTERFACE_TABLE_BEGIN                                              \
+  static const QITableEntry table[] = {
+
+#define NS_INTERFACE_TABLE_ENTRY(_class, _interface)                          \
+  { &NS_GET_IID(_interface),                                                  \
+    int32_t(reinterpret_cast<char*>(                                          \
+                        static_cast<_interface*>((_class*) 0x1000)) -         \
+               reinterpret_cast<char*>((_class*) 0x1000))                     \
+  },
+
+#define NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(_class, _interface, _implClass)    \
+  { &NS_GET_IID(_interface),                                                  \
+    int32_t(reinterpret_cast<char*>(                                          \
+                        static_cast<_interface*>(                             \
+                                       static_cast<_implClass*>(              \
+                                                      (_class*) 0x1000))) -   \
+               reinterpret_cast<char*>((_class*) 0x1000))                     \
+  },
+
+/*
+ * XXX: we want to use mozilla::ArrayLength (or equivalent,
+ * MOZ_ARRAY_LENGTH) in this condition, but some versions of GCC don't
+ * see that the static_assert condition is actually constant in those
+ * cases, even with constexpr support (?).
+ */
+#define NS_INTERFACE_TABLE_END_WITH_PTR(_ptr)                                 \
+  { nullptr, 0 } };                                                           \
+  static_assert((sizeof(table)/sizeof(table[0])) > 1, "need at least 1 interface"); \
+  rv = NS_TableDrivenQI(static_cast<void*>(_ptr),                             \
+                        aIID, aInstancePtr, table);
+
+#define NS_INTERFACE_TABLE_END                                                \
+  NS_INTERFACE_TABLE_END_WITH_PTR(this)
+
+#define NS_INTERFACE_TABLE_TAIL                                               \
+  return rv;                                                                  \
+}
+
+#define NS_INTERFACE_TABLE_TAIL_INHERITING(_baseclass)                        \
+  if (NS_SUCCEEDED(rv))                                                       \
+    return rv;                                                                \
+  return _baseclass::QueryInterface(aIID, aInstancePtr);                      \
+}
+
+#define NS_INTERFACE_TABLE_TAIL_USING_AGGREGATOR(_aggregator)                 \
+  if (NS_SUCCEEDED(rv))                                                       \
+    return rv;                                                                \
+  NS_ASSERTION(_aggregator, "null aggregator");                               \
+  return _aggregator->QueryInterface(aIID, aInstancePtr)                      \
+}
+
+/**
+ * This implements query interface with two assumptions: First, the
+ * class in question implements nsISupports and its own interface and
+ * nothing else. Second, the implementation of the class's primary
+ * inheritance chain leads to its own interface.
+ *
+ * @param _class The name of the class implementing the method
+ * @param _classiiddef The name of the #define symbol that defines the IID
+ * for the class (e.g. NS_ISUPPORTS_IID)
+ */
+
+#define NS_IMPL_QUERY_HEAD(_class)                                            \
+NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr)      \
+{                                                                             \
+  NS_ASSERTION(aInstancePtr,                                                  \
+               "QueryInterface requires a non-NULL destination!");            \
+  nsISupports* foundInterface;
+
+#define NS_IMPL_QUERY_BODY(_interface)                                        \
+  if ( aIID.Equals(NS_GET_IID(_interface)) )                                  \
+    foundInterface = static_cast<_interface*>(this);                          \
+  else
+
+#define NS_IMPL_QUERY_BODY_CONDITIONAL(_interface, condition)                 \
+  if ( (condition) && aIID.Equals(NS_GET_IID(_interface)))                    \
+    foundInterface = static_cast<_interface*>(this);                          \
+  else
+
+#define NS_IMPL_QUERY_BODY_AMBIGUOUS(_interface, _implClass)                  \
+  if ( aIID.Equals(NS_GET_IID(_interface)) )                                  \
+    foundInterface = static_cast<_interface*>(                                \
+                                    static_cast<_implClass*>(this));          \
+  else
+
+#define NS_IMPL_QUERY_BODY_AGGREGATED(_interface, _aggregate)                 \
+  if ( aIID.Equals(NS_GET_IID(_interface)) )                                  \
+    foundInterface = static_cast<_interface*>(_aggregate);                    \
+  else
+
+#define NS_IMPL_QUERY_TAIL_GUTS                                               \
+    foundInterface = 0;                                                       \
+  nsresult status;                                                            \
+  if ( !foundInterface )                                                      \
+    {                                                                         \
+      /* nsISupports should be handled by this point. If not, fail. */        \
+      MOZ_ASSERT(!aIID.Equals(NS_GET_IID(nsISupports)));                      \
+      status = NS_NOINTERFACE;                                                \
+    }                                                                         \
+  else                                                                        \
+    {                                                                         \
+      NS_ADDREF(foundInterface);                                              \
+      status = NS_OK;                                                         \
+    }                                                                         \
+  *aInstancePtr = foundInterface;                                             \
+  return status;                                                              \
+}
+
+#define NS_IMPL_QUERY_TAIL_INHERITING(_baseclass)                             \
+    foundInterface = 0;                                                       \
+  nsresult status;                                                            \
+  if ( !foundInterface )                                                      \
+    status = _baseclass::QueryInterface(aIID, (void**)&foundInterface);       \
+  else                                                                        \
+    {                                                                         \
+      NS_ADDREF(foundInterface);                                              \
+      status = NS_OK;                                                         \
+    }                                                                         \
+  *aInstancePtr = foundInterface;                                             \
+  return status;                                                              \
+}
+
+#define NS_IMPL_QUERY_TAIL_USING_AGGREGATOR(_aggregator)                      \
+    foundInterface = 0;                                                       \
+  nsresult status;                                                            \
+  if ( !foundInterface ) {                                                    \
+    NS_ASSERTION(_aggregator, "null aggregator");                             \
+    status = _aggregator->QueryInterface(aIID, (void**)&foundInterface);      \
+  } else                                                                      \
+    {                                                                         \
+      NS_ADDREF(foundInterface);                                              \
+      status = NS_OK;                                                         \
+    }                                                                         \
+  *aInstancePtr = foundInterface;                                             \
+  return status;                                                              \
+}
+
+#define NS_IMPL_QUERY_TAIL(_supports_interface)                               \
+  NS_IMPL_QUERY_BODY_AMBIGUOUS(nsISupports, _supports_interface)              \
+  NS_IMPL_QUERY_TAIL_GUTS
+
+
+/*
+  This is the new scheme.  Using this notation now will allow us to switch to
+  a table driven mechanism when it's ready.  Note the difference between this
+  and the (currently) underlying NS_IMPL_QUERY_INTERFACE mechanism.  You must
+  explicitly mention |nsISupports| when using the interface maps.
+*/
+#define NS_INTERFACE_MAP_BEGIN(_implClass)      NS_IMPL_QUERY_HEAD(_implClass)
+#define NS_INTERFACE_MAP_ENTRY(_interface)      NS_IMPL_QUERY_BODY(_interface)
+#define NS_INTERFACE_MAP_ENTRY_CONDITIONAL(_interface, condition)             \
+  NS_IMPL_QUERY_BODY_CONDITIONAL(_interface, condition)
+#define NS_INTERFACE_MAP_ENTRY_AGGREGATED(_interface,_aggregate)              \
+  NS_IMPL_QUERY_BODY_AGGREGATED(_interface,_aggregate)
+
+#define NS_INTERFACE_MAP_END                    NS_IMPL_QUERY_TAIL_GUTS
+#define NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(_interface, _implClass)              \
+  NS_IMPL_QUERY_BODY_AMBIGUOUS(_interface, _implClass)
+#define NS_INTERFACE_MAP_END_INHERITING(_baseClass)                           \
+  NS_IMPL_QUERY_TAIL_INHERITING(_baseClass)
+#define NS_INTERFACE_MAP_END_AGGREGATED(_aggregator)                          \
+  NS_IMPL_QUERY_TAIL_USING_AGGREGATOR(_aggregator)
+
+#define NS_INTERFACE_TABLE0(_class)                                           \
+  NS_INTERFACE_TABLE_BEGIN                                                    \
+    NS_INTERFACE_TABLE_ENTRY(_class, nsISupports)                             \
+  NS_INTERFACE_TABLE_END
+
+#define NS_INTERFACE_TABLE(aClass, ...)                                       \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                             \
+  NS_INTERFACE_TABLE_BEGIN                                                    \
+    MOZ_FOR_EACH(NS_INTERFACE_TABLE_ENTRY, (aClass,), (__VA_ARGS__))          \
+    NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(aClass, nsISupports,                   \
+                                       MOZ_ARG_1(__VA_ARGS__))                \
+  NS_INTERFACE_TABLE_END
+
+#define NS_IMPL_QUERY_INTERFACE0(_class)                                      \
+  NS_INTERFACE_TABLE_HEAD(_class)                                             \
+  NS_INTERFACE_TABLE0(_class)                                                 \
+  NS_INTERFACE_TABLE_TAIL
+
+#define NS_IMPL_QUERY_INTERFACE(aClass, ...)                                  \
+  NS_INTERFACE_TABLE_HEAD(aClass)                                             \
+  NS_INTERFACE_TABLE(aClass, __VA_ARGS__)                                     \
+  NS_INTERFACE_TABLE_TAIL
+
+/**
+ * Declare that you're going to inherit from something that already
+ * implements nsISupports, but also implements an additional interface, thus
+ * causing an ambiguity. In this case you don't need another mRefCnt, you
+ * just need to forward the definitions to the appropriate superclass. E.g.
+ *
+ * class Bar : public Foo, public nsIBar {  // both provide nsISupports
+ * public:
+ *   NS_DECL_ISUPPORTS_INHERITED
+ *   ...other nsIBar and Bar methods...
+ * };
+ */
+#define NS_DECL_ISUPPORTS_INHERITED                                           \
+public:                                                                       \
+  NS_IMETHOD QueryInterface(REFNSIID aIID,                                    \
+                            void** aInstancePtr) override;                \
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;             \
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) override;            \
+
+/**
+ * These macros can be used in conjunction with NS_DECL_ISUPPORTS_INHERITED
+ * to implement the nsISupports methods, forwarding the invocations to a
+ * superclass that already implements nsISupports.
+ *
+ * Note that I didn't make these inlined because they're virtual methods.
+ */
+
+#define NS_IMPL_ADDREF_INHERITED(Class, Super)                                \
+NS_IMETHODIMP_(MozExternalRefCountType) Class::AddRef(void)                   \
+{                                                                             \
+  MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(Class)                                   \
+  nsrefcnt r = Super::AddRef();                                               \
+  NS_LOG_ADDREF(this, r, #Class, sizeof(*this));                              \
+  return r;                                                                   \
+}
+
+#define NS_IMPL_RELEASE_INHERITED(Class, Super)                               \
+NS_IMETHODIMP_(MozExternalRefCountType) Class::Release(void)                  \
+{                                                                             \
+  nsrefcnt r = Super::Release();                                              \
+  NS_LOG_RELEASE(this, r, #Class);                                            \
+  return r;                                                                   \
+}
+
+/**
+ * As above but not logging the addref/release; needed if the base
+ * class might be aggregated.
+ */
+#define NS_IMPL_NONLOGGING_ADDREF_INHERITED(Class, Super)                     \
+NS_IMETHODIMP_(MozExternalRefCountType) Class::AddRef(void)                   \
+{                                                                             \
+  MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(Class)                                   \
+  return Super::AddRef();                                                     \
+}
+
+#define NS_IMPL_NONLOGGING_RELEASE_INHERITED(Class, Super)                    \
+NS_IMETHODIMP_(MozExternalRefCountType) Class::Release(void)                  \
+{                                                                             \
+  return Super::Release();                                                    \
+}
+
+#define NS_INTERFACE_TABLE_INHERITED0(Class) /* Nothing to do here */
+
+#define NS_INTERFACE_TABLE_INHERITED(aClass, ...)                             \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                             \
+  NS_INTERFACE_TABLE_BEGIN                                                    \
+    MOZ_FOR_EACH(NS_INTERFACE_TABLE_ENTRY, (aClass,), (__VA_ARGS__))          \
+  NS_INTERFACE_TABLE_END
+
+#define NS_IMPL_QUERY_INTERFACE_INHERITED(aClass, aSuper, ...)                \
+  NS_INTERFACE_TABLE_HEAD(aClass)                                             \
+  NS_INTERFACE_TABLE_INHERITED(aClass, __VA_ARGS__)                           \
+  NS_INTERFACE_TABLE_TAIL_INHERITING(aSuper)
+
+/**
+ * Convenience macros for implementing all nsISupports methods for
+ * a simple class.
+ * @param _class The name of the class implementing the method
+ * @param _classiiddef The name of the #define symbol that defines the IID
+ * for the class (e.g. NS_ISUPPORTS_IID)
+ */
+
+#define NS_IMPL_ISUPPORTS0(_class)                                            \
+  NS_IMPL_ADDREF(_class)                                                      \
+  NS_IMPL_RELEASE(_class)                                                     \
+  NS_IMPL_QUERY_INTERFACE0(_class)
+
+#define NS_IMPL_ISUPPORTS(aClass, ...)                                        \
+  NS_IMPL_ADDREF(aClass)                                                      \
+  NS_IMPL_RELEASE(aClass)                                                     \
+  NS_IMPL_QUERY_INTERFACE(aClass, __VA_ARGS__)
+
+#define NS_IMPL_ISUPPORTS_INHERITED0(aClass, aSuper)                          \
+    NS_INTERFACE_TABLE_HEAD(aClass)                                           \
+    NS_INTERFACE_TABLE_TAIL_INHERITING(aSuper)                                \
+    NS_IMPL_ADDREF_INHERITED(aClass, aSuper)                                  \
+    NS_IMPL_RELEASE_INHERITED(aClass, aSuper)                                 \
+
+#define NS_IMPL_ISUPPORTS_INHERITED(aClass, aSuper, ...)                      \
+  NS_IMPL_QUERY_INTERFACE_INHERITED(aClass, aSuper, __VA_ARGS__)              \
+  NS_IMPL_ADDREF_INHERITED(aClass, aSuper)                                    \
+  NS_IMPL_RELEASE_INHERITED(aClass, aSuper)
+
+/*
+ * Macro to glue together a QI that starts with an interface table
+ * and segues into an interface map (e.g. it uses singleton classinfo
+ * or tearoffs).
+ */
+#define NS_INTERFACE_TABLE_TO_MAP_SEGUE \
+  if (rv == NS_OK) return rv; \
+  nsISupports* foundInterface;
+
+
+///////////////////////////////////////////////////////////////////////////////
+/**
+ *
+ * Threadsafe implementations of the ISupports convenience macros.
+ *
+ * @note  These are not available when linking against the standalone glue,
+ *        because the implementation requires PR_ symbols.
+ */
+#define NS_INTERFACE_MAP_END_THREADSAFE NS_IMPL_QUERY_TAIL_GUTS
+
+/**
+ * Macro to generate nsIClassInfo methods for classes which do not have
+ * corresponding nsIFactory implementations.
+ */
+#define NS_IMPL_THREADSAFE_CI(_class)                                         \
+NS_IMETHODIMP                                                                 \
+_class::GetInterfaces(uint32_t* _count, nsIID*** _array)                      \
+{                                                                             \
+  return NS_CI_INTERFACE_GETTER_NAME(_class)(_count, _array);                 \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetScriptableHelper(nsIXPCScriptable** _retval)                       \
+{                                                                             \
+  *_retval = nullptr;                                                         \
+  return NS_OK;                                                               \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetContractID(char** _contractID)                                     \
+{                                                                             \
+  *_contractID = nullptr;                                                     \
+  return NS_OK;                                                               \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetClassDescription(char** _classDescription)                         \
+{                                                                             \
+  *_classDescription = nullptr;                                               \
+  return NS_OK;                                                               \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetClassID(nsCID** _classID)                                          \
+{                                                                             \
+  *_classID = nullptr;                                                        \
+  return NS_OK;                                                               \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetFlags(uint32_t* _flags)                                            \
+{                                                                             \
+  *_flags = nsIClassInfo::THREADSAFE;                                         \
+  return NS_OK;                                                               \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetClassIDNoAlloc(nsCID* _classIDNoAlloc)                             \
+{                                                                             \
+  return NS_ERROR_NOT_AVAILABLE;                                              \
+}
+
+#endif
diff --git a/xpcom/glue/nsISupportsUtils.h b/xpcom/glue/nsISupportsUtils.h
new file mode 100644
index 0000000000..4d306d3d1a
--- /dev/null
+++ b/xpcom/glue/nsISupportsUtils.h
@@ -0,0 +1,145 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsISupportsUtils_h__
+#define nsISupportsUtils_h__
+
+#include "nscore.h"
+#include "nsISupportsBase.h"
+#include "nsError.h"
+#include "nsDebug.h"
+#include "nsISupportsImpl.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/TypeTraits.h"
+
+/**
+ * Macro for adding a reference to an interface.
+ * @param _ptr The interface pointer.
+ */
+#define NS_ADDREF(_ptr) \
+  (_ptr)->AddRef()
+
+/**
+ * Macro for adding a reference to this. This macro should be used
+ * because NS_ADDREF (when tracing) may require an ambiguous cast
+ * from the pointers primary type to nsISupports. This macro sidesteps
+ * that entire problem.
+ */
+#define NS_ADDREF_THIS() \
+  AddRef()
+
+
+// Making this a |inline| |template| allows |aExpr| to be evaluated only once,
+// yet still denies you the ability to |AddRef()| an |nsCOMPtr|.
+template<class T>
+inline void
+ns_if_addref(T aExpr)
+{
+  if (aExpr) {
+    aExpr->AddRef();
+  }
+}
+
+/**
+ * Macro for adding a reference to an interface that checks for nullptr.
+ * @param _expr The interface pointer.
+ */
+#define NS_IF_ADDREF(_expr) ns_if_addref(_expr)
+
+/*
+ * Given these declarations, it explicitly OK and efficient to end a `getter' with:
+ *
+ *    NS_IF_ADDREF(*result = mThing);
+ *
+ * even if |mThing| is an |nsCOMPtr|.  If |mThing| is an |nsCOMPtr|, however, it is still
+ * _illegal_ to say |NS_IF_ADDREF(mThing)|.
+ */
+
+/**
+ * Macro for releasing a reference to an interface.
+ * @param _ptr The interface pointer.
+ */
+#define NS_RELEASE(_ptr)                                                      \
+  do {                                                                        \
+    (_ptr)->Release();                                                        \
+    (_ptr) = 0;                                                               \
+  } while (0)
+
+/**
+ * Macro for releasing a reference to this interface.
+ */
+#define NS_RELEASE_THIS() \
+    Release()
+
+/**
+ * Macro for releasing a reference to an interface, except that this
+ * macro preserves the return value from the underlying Release call.
+ * The interface pointer argument will only be NULLed if the reference count
+ * goes to zero.
+ *
+ * @param _ptr The interface pointer.
+ * @param _rc  The reference count.
+ */
+#define NS_RELEASE2(_ptr, _rc)                                                \
+  do {                                                                        \
+    _rc = (_ptr)->Release();                                                  \
+    if (0 == (_rc)) (_ptr) = 0;                                               \
+  } while (0)
+
+/**
+ * Macro for releasing a reference to an interface that checks for nullptr;
+ * @param _ptr The interface pointer.
+ */
+#define NS_IF_RELEASE(_ptr)                                                   \
+  do {                                                                        \
+    if (_ptr) {                                                               \
+      (_ptr)->Release();                                                      \
+      (_ptr) = 0;                                                             \
+    }                                                                         \
+  } while (0)
+
+/*
+ * Often you have to cast an implementation pointer, e.g., |this|, to an
+ * |nsISupports*|, but because you have multiple inheritance, a simple cast
+ * is ambiguous.  One could simply say, e.g., (given a base |nsIBase|),
+ * |static_cast<nsIBase*>(this)|; but that disguises the fact that what
+ * you are really doing is disambiguating the |nsISupports|.  You could make
+ * that more obvious with a double cast, e.g., |static_cast<nsISupports*>
+                                                           (* static_cast<nsIBase*>(this))|, but that is bulky and harder to read...
+ *
+ * The following macro is clean, short, and obvious.  In the example above,
+ * you would use it like this: |NS_ISUPPORTS_CAST(nsIBase*, this)|.
+ */
+
+#define NS_ISUPPORTS_CAST(__unambiguousBase, __expr) \
+  static_cast<nsISupports*>(static_cast<__unambiguousBase>(__expr))
+
+// a type-safe shortcut for calling the |QueryInterface()| member function
+template<class T, class DestinationType>
+inline nsresult
+CallQueryInterface(T* aSource, DestinationType** aDestination)
+{
+  // We permit nsISupports-to-nsISupports here so that one can still obtain
+  // the canonical nsISupports pointer with CallQueryInterface.
+  static_assert(!mozilla::IsSame<T, DestinationType>::value ||
+                mozilla::IsSame<DestinationType, nsISupports>::value,
+                "don't use CallQueryInterface for compile-time-determinable casts");
+
+  NS_PRECONDITION(aSource, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return aSource->QueryInterface(NS_GET_TEMPLATE_IID(DestinationType),
+                                 reinterpret_cast<void**>(aDestination));
+}
+
+template <class SourceType, class DestinationType>
+inline nsresult
+CallQueryInterface(RefPtr<SourceType>& aSourcePtr, DestinationType** aDestPtr)
+{
+  return CallQueryInterface(aSourcePtr.get(), aDestPtr);
+}
+
+#endif /* __nsISupportsUtils_h */
diff --git a/xpcom/glue/nsIWeakReferenceUtils.h b/xpcom/glue/nsIWeakReferenceUtils.h
new file mode 100644
index 0000000000..1c84e00dfb
--- /dev/null
+++ b/xpcom/glue/nsIWeakReferenceUtils.h
@@ -0,0 +1,102 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsIWeakReferenceUtils_h__
+#define nsIWeakReferenceUtils_h__
+
+#include "nsCOMPtr.h"
+#include "nsIWeakReference.h"
+
+typedef nsCOMPtr<nsIWeakReference> nsWeakPtr;
+
+/**
+ *
+ */
+
+// a type-safe shortcut for calling the |QueryReferent()| member function
+// T must inherit from nsIWeakReference, but the cast may be ambiguous.
+template<class T, class DestinationType>
+inline nsresult
+CallQueryReferent(T* aSource, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aSource, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return aSource->QueryReferent(NS_GET_TEMPLATE_IID(DestinationType),
+                                reinterpret_cast<void**>(aDestination));
+}
+
+
+class MOZ_STACK_CLASS nsQueryReferent final : public nsCOMPtr_helper
+{
+public:
+  nsQueryReferent(nsIWeakReference* aWeakPtr, nsresult* aError)
+    : mWeakPtr(aWeakPtr)
+    , mErrorPtr(aError)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const
+    override;
+
+private:
+  nsIWeakReference* MOZ_NON_OWNING_REF mWeakPtr;
+  nsresult*          mErrorPtr;
+};
+
+inline const nsQueryReferent
+do_QueryReferent(nsIWeakReference* aRawPtr, nsresult* aError = 0)
+{
+  return nsQueryReferent(aRawPtr, aError);
+}
+
+
+/**
+ * Deprecated, use |do_GetWeakReference| instead.
+ */
+extern nsIWeakReference* NS_GetWeakReference(nsISupports*,
+                                             nsresult* aResult = 0);
+
+/**
+ * |do_GetWeakReference| is a convenience function that bundles up all the work needed
+ * to get a weak reference to an arbitrary object, i.e., the |QueryInterface|, test, and
+ * call through to |GetWeakReference|, and put it into your |nsCOMPtr|.
+ * It is specifically designed to cooperate with |nsCOMPtr| (or |nsWeakPtr|) like so:
+ * |nsWeakPtr myWeakPtr = do_GetWeakReference(aPtr);|.
+ */
+inline already_AddRefed<nsIWeakReference>
+do_GetWeakReference(nsISupports* aRawPtr, nsresult* aError = 0)
+{
+  return dont_AddRef(NS_GetWeakReference(aRawPtr, aError));
+}
+
+inline void
+do_GetWeakReference(nsIWeakReference* aRawPtr, nsresult* aError = 0)
+{
+  // This signature exists solely to _stop_ you from doing a bad thing.
+  //  Saying |do_GetWeakReference()| on a weak reference itself,
+  //  is very likely to be a programmer error.
+}
+
+template<class T>
+inline void
+do_GetWeakReference(already_AddRefed<T>&)
+{
+  // This signature exists solely to _stop_ you from doing the bad thing.
+  //  Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
+  //  someone else is an automatic leak.  See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
+}
+
+template<class T>
+inline void
+do_GetWeakReference(already_AddRefed<T>&, nsresult*)
+{
+  // This signature exists solely to _stop_ you from doing the bad thing.
+  //  Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
+  //  someone else is an automatic leak.  See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
+}
+
+#endif
diff --git a/xpcom/glue/nsInterfaceHashtable.h b/xpcom/glue/nsInterfaceHashtable.h
new file mode 100644
index 0000000000..14368af637
--- /dev/null
+++ b/xpcom/glue/nsInterfaceHashtable.h
@@ -0,0 +1,142 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsInterfaceHashtable_h__
+#define nsInterfaceHashtable_h__
+
+#include "nsBaseHashtable.h"
+#include "nsHashKeys.h"
+#include "nsCOMPtr.h"
+
+/**
+ * templated hashtable class maps keys to interface pointers.
+ * See nsBaseHashtable for complete declaration.
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param Interface the interface-type being wrapped
+ * @see nsDataHashtable, nsClassHashtable
+ */
+template<class KeyClass, class Interface>
+class nsInterfaceHashtable
+  : public nsBaseHashtable<KeyClass, nsCOMPtr<Interface>, Interface*>
+{
+public:
+  typedef typename KeyClass::KeyType KeyType;
+  typedef Interface* UserDataType;
+  typedef nsBaseHashtable<KeyClass, nsCOMPtr<Interface>, Interface*> base_type;
+
+  nsInterfaceHashtable() {}
+  explicit nsInterfaceHashtable(uint32_t aInitLength)
+    : nsBaseHashtable<KeyClass, nsCOMPtr<Interface>, Interface*>(aInitLength)
+  {
+  }
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   * @param aData This is an XPCOM getter, so aData is already_addrefed.
+   *   If the key doesn't exist, aData will be set to nullptr.
+   */
+  bool Get(KeyType aKey, UserDataType* aData) const;
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   */
+  already_AddRefed<Interface> Get(KeyType aKey) const;
+
+  /**
+   * Gets a weak reference to the hashtable entry.
+   * @param aFound If not nullptr, will be set to true if the entry is found,
+   *               to false otherwise.
+   * @return The entry, or nullptr if not found. Do not release this pointer!
+   */
+  Interface* GetWeak(KeyType aKey, bool* aFound = nullptr) const;
+};
+
+template<typename K, typename T>
+inline void
+ImplCycleCollectionUnlink(nsInterfaceHashtable<K, T>& aField)
+{
+  aField.Clear();
+}
+
+template<typename K, typename T>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            const nsInterfaceHashtable<K, T>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  for (auto iter = aField.ConstIter(); !iter.Done(); iter.Next()) {
+    CycleCollectionNoteChild(aCallback, iter.UserData(), aName, aFlags);
+  }
+}
+
+//
+// nsInterfaceHashtable definitions
+//
+
+template<class KeyClass, class Interface>
+bool
+nsInterfaceHashtable<KeyClass, Interface>::Get(KeyType aKey,
+                                               UserDataType* aInterface) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aInterface) {
+      *aInterface = ent->mData;
+
+      NS_IF_ADDREF(*aInterface);
+    }
+
+    return true;
+  }
+
+  // if the key doesn't exist, set *aInterface to null
+  // so that it is a valid XPCOM getter
+  if (aInterface) {
+    *aInterface = nullptr;
+  }
+
+  return false;
+}
+
+template<class KeyClass, class Interface>
+already_AddRefed<Interface>
+nsInterfaceHashtable<KeyClass, Interface>::Get(KeyType aKey) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+  if (!ent) {
+    return nullptr;
+  }
+
+  nsCOMPtr<Interface> copy = ent->mData;
+  return copy.forget();
+}
+
+template<class KeyClass, class Interface>
+Interface*
+nsInterfaceHashtable<KeyClass, Interface>::GetWeak(KeyType aKey,
+                                                   bool* aFound) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aFound) {
+      *aFound = true;
+    }
+
+    return ent->mData;
+  }
+
+  // Key does not exist, return nullptr and set aFound to false
+  if (aFound) {
+    *aFound = false;
+  }
+  return nullptr;
+}
+
+#endif // nsInterfaceHashtable_h__
diff --git a/xpcom/glue/nsJSThingHashtable.h b/xpcom/glue/nsJSThingHashtable.h
new file mode 100644
index 0000000000..8c1b1447d2
--- /dev/null
+++ b/xpcom/glue/nsJSThingHashtable.h
@@ -0,0 +1,61 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsJSThingHashtable_h__
+#define nsJSThingHashtable_h__
+
+#include "nsHashKeys.h"
+#include "nsBaseHashtable.h"
+
+namespace JS {
+template<class T>
+class Heap;
+} /* namespace JS */
+
+/**
+ * A wrapper for hash keys that sets ALLOW_MEMMOVE to false.
+ *
+ * This is used in the implementation of nsJSThingHashtable and is not intended
+ * to be used directly.
+ *
+ * It is necessary for hash tables containing JS::Heap<T> values as these must
+ * be copied rather than memmoved.
+ */
+template<class T>
+class nsHashKeyDisallowMemmove : public T
+{
+public:
+  explicit nsHashKeyDisallowMemmove(const typename T::KeyTypePointer aKey) : T(aKey) {}
+  enum { ALLOW_MEMMOVE = false };
+};
+
+
+/**
+ * Templated hashtable class for use on the heap where the values are JS GC things.
+ *
+ * Storing JS GC thing pointers on the heap requires wrapping them in a
+ * JS::Heap<T>, and this class takes care of that while presenting an interface
+ * in terms of the wrapped type T.
+ *
+ * For example, to store a hashtable mapping strings to JSObject pointers, you
+ * can declare a data member like this:
+ *
+ *   nsJSThingHashtable<nsStringHashKey, JSObject*> mStringToObjectMap;
+ *
+ * See nsBaseHashtable for complete declaration
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param DataType the datatype being wrapped, must be a JS GC thing.
+ * @see nsInterfaceHashtable, nsClassHashtable
+ */
+template<class KeyClass, class DataType>
+class nsJSThingHashtable
+  : public nsBaseHashtable<nsHashKeyDisallowMemmove<KeyClass>,
+                           JS::Heap<DataType>, DataType>
+{
+};
+
+#endif // nsJSThingHashtable_h__
diff --git a/xpcom/glue/nsMemory.cpp b/xpcom/glue/nsMemory.cpp
new file mode 100644
index 0000000000..3bf7c1f0fe
--- /dev/null
+++ b/xpcom/glue/nsMemory.cpp
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsXPCOM.h"
+#include "nsMemory.h"
+#include "nsIMemory.h"
+#include "nsXPCOMPrivate.h"
+#include "nsDebug.h"
+#include "nsISupportsUtils.h"
+#include "nsCOMPtr.h"
+
+////////////////////////////////////////////////////////////////////////////////
+// nsMemory static helper routines
+
+nsresult
+nsMemory::HeapMinimize(bool aImmediate)
+{
+  nsCOMPtr<nsIMemory> mem;
+  nsresult rv = NS_GetMemoryManager(getter_AddRefs(mem));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  return mem->HeapMinimize(aImmediate);
+}
+
+void*
+nsMemory::Clone(const void* aPtr, size_t aSize)
+{
+  void* newPtr = NS_Alloc(aSize);
+  if (newPtr) {
+    memcpy(newPtr, aPtr, aSize);
+  }
+  return newPtr;
+}
+
+nsIMemory*
+nsMemory::GetGlobalMemoryService()
+{
+  nsIMemory* mem;
+  nsresult rv = NS_GetMemoryManager(&mem);
+  if (NS_FAILED(rv)) {
+    return nullptr;
+  }
+
+  return mem;
+}
+
+//----------------------------------------------------------------------
+
diff --git a/xpcom/glue/nsMemory.h b/xpcom/glue/nsMemory.h
new file mode 100644
index 0000000000..6f19b81171
--- /dev/null
+++ b/xpcom/glue/nsMemory.h
@@ -0,0 +1,136 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMemory_h__
+#define nsMemory_h__
+
+#include "nsXPCOM.h"
+
+class nsIMemory;
+
+#define NS_MEMORY_CONTRACTID "@mozilla.org/xpcom/memory-service;1"
+#define NS_MEMORY_CID                                \
+{ /* 30a04e40-38e7-11d4-8cf5-0060b0fc14a3 */         \
+    0x30a04e40,                                      \
+    0x38e7,                                          \
+    0x11d4,                                          \
+    {0x8c, 0xf5, 0x00, 0x60, 0xb0, 0xfc, 0x14, 0xa3} \
+}
+
+
+/**
+ * Static helper routines to manage memory. These routines allow easy access
+ * to xpcom's built-in (global) nsIMemory implementation, without needing
+ * to go through the service manager to get it. However this requires clients
+ * to link with the xpcom DLL.
+ *
+ * This class is not threadsafe and is intented for use only on the main
+ * thread.
+ */
+class nsMemory
+{
+public:
+  static nsresult   HeapMinimize(bool aImmediate);
+  static void*      Clone(const void* aPtr, size_t aSize);
+  static nsIMemory* GetGlobalMemoryService();       // AddRefs
+};
+
+/**
+ * Macro to free all elements of an XPCOM array of a given size using
+ * freeFunc, then frees the array itself using free().
+ *
+ * Note that this macro (and its wrappers) can be used to deallocate a
+ * partially- or completely-built array while unwinding an error
+ * condition inside the XPCOM routine that was going to return the
+ * array.  For this to work on a partially-built array, your code
+ * needs to be building the array from index 0 upwards, and simply
+ * pass the number of elements that have already been built (and thus
+ * need to be freed) as |size|.
+ *
+ * Thanks to <alecf@netscape.com> for suggesting this form, which
+ * allows the macro to be used with NS_RELEASE / NS_RELEASE_IF in
+ * addition to free.
+ *
+ * @param size      Number of elements in the array.  If not a constant, this
+ *                  should be a int32_t.  Note that this means this macro
+ *                  will not work if size >= 2^31.
+ * @param array     The array to be freed.
+ * @param freeFunc  The function or macro to be used to free it.
+ *                  For arrays of nsISupports (or any class derived
+ *                  from it), NS_IF_RELEASE (or NS_RELEASE) should be
+ *                  passed as freeFunc.  For most (all?) other pointer
+ *                  types (including XPCOM strings and wstrings),
+ *                  free should be used.
+ */
+#define NS_FREE_XPCOM_POINTER_ARRAY(size, array, freeFunc)                    \
+    PR_BEGIN_MACRO                                                            \
+        int32_t iter_ = int32_t(size);                                        \
+        while (--iter_ >= 0)                                                  \
+            freeFunc((array)[iter_]);                                         \
+        NS_Free((array));                                                     \
+    PR_END_MACRO
+
+// convenience macros for commonly used calls.  mmmmm.  syntactic sugar.
+
+/**
+ * Macro to free arrays of non-refcounted objects allocated by the
+ * shared allocator (nsMemory) such as strings and wstrings.  A
+ * convenience wrapper around NS_FREE_XPCOM_POINTER_ARRAY.
+ *
+ * @param size      Number of elements in the array.  If not a constant, this
+ *                  should be a int32_t.  Note that this means this macro
+ *                  will not work if size >= 2^31.
+ * @param array     The array to be freed.
+ */
+#define NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(size, array)                    \
+    NS_FREE_XPCOM_POINTER_ARRAY((size), (array), NS_Free)
+
+/**
+ * Macro to free an array of pointers to nsISupports (or classes
+ * derived from it).  A convenience wrapper around
+ * NS_FREE_XPCOM_POINTER_ARRAY.
+ *
+ * Note that if you know that none of your nsISupports pointers are
+ * going to be 0, you can gain a bit of speed by calling
+ * NS_FREE_XPCOM_POINTER_ARRAY directly and using NS_RELEASE as your
+ * free function.
+ *
+ * @param size      Number of elements in the array.  If not a constant, this
+ *                  should be a int32_t.  Note that this means this macro
+ *                  will not work if size >= 2^31.
+ * @param array     The array to be freed.
+ */
+#define NS_FREE_XPCOM_ISUPPORTS_POINTER_ARRAY(size, array)                    \
+    NS_FREE_XPCOM_POINTER_ARRAY((size), (array), NS_IF_RELEASE)
+
+/**
+ * A macro, NS_ALIGNMENT_OF(t_) that determines the alignment
+ * requirements of a type.
+ */
+namespace mozilla {
+template<class T>
+struct AlignmentTestStruct
+{
+  char c;
+  T t;
+};
+} // namespace mozilla
+
+#define NS_ALIGNMENT_OF(t_) \
+  (sizeof(mozilla::AlignmentTestStruct<t_>) - sizeof(t_))
+
+/**
+ * An enumeration type used to represent a method of assignment.
+ */
+enum nsAssignmentType
+{
+  NS_ASSIGNMENT_COPY,   // copy by value
+  NS_ASSIGNMENT_DEPEND, // copy by reference
+  NS_ASSIGNMENT_ADOPT   // copy by reference (take ownership of resource)
+};
+
+#endif // nsMemory_h__
+
diff --git a/xpcom/glue/nsPointerHashKeys.h b/xpcom/glue/nsPointerHashKeys.h
new file mode 100644
index 0000000000..a89843101c
--- /dev/null
+++ b/xpcom/glue/nsPointerHashKeys.h
@@ -0,0 +1,48 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Definitions for nsPtrHashKey<T> and nsVoidPtrHashKey.  */
+
+#ifndef nsPointerHashKeys_h
+#define nsPointerHashKeys_h
+
+#include "nscore.h"
+
+#include "mozilla/Attributes.h"
+
+/**
+ * hashkey wrapper using T* KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+template<class T>
+class nsPtrHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef T* KeyType;
+  typedef const T* KeyTypePointer;
+
+  explicit nsPtrHashKey(const T* aKey) : mKey(const_cast<T*>(aKey)) {}
+  nsPtrHashKey(const nsPtrHashKey<T>& aToCopy) : mKey(aToCopy.mKey) {}
+  ~nsPtrHashKey() {}
+
+  KeyType GetKey() const { return mKey; }
+  bool KeyEquals(KeyTypePointer aKey) const { return aKey == mKey; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return NS_PTR_TO_UINT32(aKey) >> 2;
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+protected:
+  T* MOZ_NON_OWNING_REF mKey;
+};
+
+typedef nsPtrHashKey<const void> nsVoidPtrHashKey;
+
+#endif // nsPointerHashKeys_h
diff --git a/xpcom/glue/nsProxyRelease.cpp b/xpcom/glue/nsProxyRelease.cpp
new file mode 100644
index 0000000000..1a8150cc6f
--- /dev/null
+++ b/xpcom/glue/nsProxyRelease.cpp
@@ -0,0 +1,21 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsProxyRelease.h"
+#include "nsThreadUtils.h"
+
+namespace detail {
+
+/* static */ void
+ProxyReleaseChooser<true>::ProxyReleaseISupports(nsIEventTarget* aTarget,
+                                                 nsISupports* aDoomed,
+                                                 bool aAlwaysProxy)
+{
+  ::detail::ProxyRelease<nsISupports>(aTarget, dont_AddRef(aDoomed),
+                                      aAlwaysProxy);
+}
+
+} // namespace detail
diff --git a/xpcom/glue/nsProxyRelease.h b/xpcom/glue/nsProxyRelease.h
new file mode 100644
index 0000000000..d99f970b9f
--- /dev/null
+++ b/xpcom/glue/nsProxyRelease.h
@@ -0,0 +1,353 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsProxyRelease_h__
+#define nsProxyRelease_h__
+
+#include "nsIEventTarget.h"
+#include "nsIThread.h"
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "MainThreadUtils.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Likely.h"
+#include "mozilla/Move.h"
+#include "mozilla/TypeTraits.h"
+#include "mozilla/Unused.h"
+
+#ifdef XPCOM_GLUE_AVOID_NSPR
+#error NS_ProxyRelease implementation depends on NSPR.
+#endif
+
+namespace detail {
+
+template<typename T>
+class ProxyReleaseEvent : public mozilla::Runnable
+{
+public:
+  explicit ProxyReleaseEvent(already_AddRefed<T> aDoomed)
+  : mDoomed(aDoomed.take()) {}
+
+  NS_IMETHOD Run() override
+  {
+    NS_IF_RELEASE(mDoomed);
+    return NS_OK;
+  }
+
+private:
+  T* MOZ_OWNING_REF mDoomed;
+};
+
+template<typename T>
+void
+ProxyRelease(nsIEventTarget* aTarget, already_AddRefed<T> aDoomed, bool aAlwaysProxy)
+{
+  // Auto-managing release of the pointer.
+  RefPtr<T> doomed = aDoomed;
+  nsresult rv;
+
+  if (!doomed || !aTarget) {
+    return;
+  }
+
+  if (!aAlwaysProxy) {
+    bool onCurrentThread = false;
+    rv = aTarget->IsOnCurrentThread(&onCurrentThread);
+    if (NS_SUCCEEDED(rv) && onCurrentThread) {
+      return;
+    }
+  }
+
+  nsCOMPtr<nsIRunnable> ev = new ProxyReleaseEvent<T>(doomed.forget());
+
+  rv = aTarget->Dispatch(ev, NS_DISPATCH_NORMAL);
+  if (NS_FAILED(rv)) {
+    NS_WARNING("failed to post proxy release event, leaking!");
+    // It is better to leak the aDoomed object than risk crashing as
+    // a result of deleting it on the wrong thread.
+  }
+}
+
+template<bool nsISupportsBased>
+struct ProxyReleaseChooser
+{
+  template<typename T>
+  static void ProxyRelease(nsIEventTarget* aTarget,
+                           already_AddRefed<T> aDoomed,
+                           bool aAlwaysProxy)
+  {
+    ::detail::ProxyRelease(aTarget, mozilla::Move(aDoomed), aAlwaysProxy);
+  }
+};
+
+template<>
+struct ProxyReleaseChooser<true>
+{
+  // We need an intermediate step for handling classes with ambiguous
+  // inheritance to nsISupports.
+  template<typename T>
+  static void ProxyRelease(nsIEventTarget* aTarget,
+                           already_AddRefed<T> aDoomed,
+                           bool aAlwaysProxy)
+  {
+    ProxyReleaseISupports(aTarget, ToSupports(aDoomed.take()), aAlwaysProxy);
+  }
+
+  static void ProxyReleaseISupports(nsIEventTarget* aTarget,
+                                    nsISupports* aDoomed,
+                                    bool aAlwaysProxy);
+};
+
+} // namespace detail
+
+/**
+ * Ensures that the delete of a smart pointer occurs on the target thread.
+ *
+ * @param aTarget
+ *        the target thread where the doomed object should be released.
+ * @param aDoomed
+ *        the doomed object; the object to be released on the target thread.
+ * @param aAlwaysProxy
+ *        normally, if NS_ProxyRelease is called on the target thread, then the
+ *        doomed object will be released directly. However, if this parameter is
+ *        true, then an event will always be posted to the target thread for
+ *        asynchronous release.
+ */
+template<class T>
+inline NS_HIDDEN_(void)
+NS_ProxyRelease(nsIEventTarget* aTarget, already_AddRefed<T> aDoomed,
+                bool aAlwaysProxy = false)
+{
+  ::detail::ProxyReleaseChooser<mozilla::IsBaseOf<nsISupports, T>::value>
+    ::ProxyRelease(aTarget, mozilla::Move(aDoomed), aAlwaysProxy);
+}
+
+/**
+ * Ensures that the delete of a smart pointer occurs on the main thread.
+ *
+ * @param aDoomed
+ *        the doomed object; the object to be released on the main thread.
+ * @param aAlwaysProxy
+ *        normally, if NS_ReleaseOnMainThread is called on the main thread,
+ *        then the doomed object will be released directly. However, if this
+ *        parameter is true, then an event will always be posted to the main
+ *        thread for asynchronous release.
+ */
+template<class T>
+inline NS_HIDDEN_(void)
+NS_ReleaseOnMainThread(already_AddRefed<T> aDoomed,
+                       bool aAlwaysProxy = false)
+{
+  // NS_ProxyRelease treats a null event target as "the current thread".  So a
+  // handle on the main thread is only necessary when we're not already on the
+  // main thread or the release must happen asynchronously.
+  nsCOMPtr<nsIThread> mainThread;
+  if (!NS_IsMainThread() || aAlwaysProxy) {
+    nsresult rv = NS_GetMainThread(getter_AddRefs(mainThread));
+
+    if (NS_FAILED(rv)) {
+      MOZ_ASSERT_UNREACHABLE("Could not get main thread; leaking an object!");
+      mozilla::Unused << aDoomed.take();
+      return;
+    }
+  }
+
+  NS_ProxyRelease(mainThread, mozilla::Move(aDoomed), aAlwaysProxy);
+}
+
+/**
+ * Class to safely handle main-thread-only pointers off the main thread.
+ *
+ * Classes like XPCWrappedJS are main-thread-only, which means that it is
+ * forbidden to call methods on instances of these classes off the main thread.
+ * For various reasons (see bug 771074), this restriction recently began to
+ * apply to AddRef/Release as well.
+ *
+ * This presents a problem for consumers that wish to hold a callback alive
+ * on non-main-thread code. A common example of this is the proxy callback
+ * pattern, where non-main-thread code holds a strong-reference to the callback
+ * object, and dispatches new Runnables (also with a strong reference) to the
+ * main thread in order to execute the callback. This involves several AddRef
+ * and Release calls on the other thread, which is (now) verboten.
+ *
+ * The basic idea of this class is to introduce a layer of indirection.
+ * nsMainThreadPtrHolder is a threadsafe reference-counted class that internally
+ * maintains one strong reference to the main-thread-only object. It must be
+ * instantiated on the main thread (so that the AddRef of the underlying object
+ * happens on the main thread), but consumers may subsequently pass references
+ * to the holder anywhere they please. These references are meant to be opaque
+ * when accessed off-main-thread (assertions enforce this).
+ *
+ * The semantics of RefPtr<nsMainThreadPtrHolder<T> > would be cumbersome, so
+ * we also introduce nsMainThreadPtrHandle<T>, which is conceptually identical
+ * to the above (though it includes various convenience methods). The basic
+ * pattern is as follows.
+ *
+ * // On the main thread:
+ * nsCOMPtr<nsIFooCallback> callback = ...;
+ * nsMainThreadPtrHandle<nsIFooCallback> callbackHandle =
+ *   new nsMainThreadPtrHolder<nsIFooCallback>(callback);
+ * // Pass callbackHandle to structs/classes that might be accessed on other
+ * // threads.
+ *
+ * All structs and classes that might be accessed on other threads should store
+ * an nsMainThreadPtrHandle<T> rather than an nsCOMPtr<T>.
+ */
+template<class T>
+class nsMainThreadPtrHolder final
+{
+public:
+  // We can only acquire a pointer on the main thread. We to fail fast for
+  // threading bugs, so by default we assert if our pointer is used or acquired
+  // off-main-thread. But some consumers need to use the same pointer for
+  // multiple classes, some of which are main-thread-only and some of which
+  // aren't. So we allow them to explicitly disable this strict checking.
+  explicit nsMainThreadPtrHolder(T* aPtr, bool aStrict = true)
+    : mRawPtr(nullptr)
+    , mStrict(aStrict)
+  {
+    // We can only AddRef our pointer on the main thread, which means that the
+    // holder must be constructed on the main thread.
+    MOZ_ASSERT(!mStrict || NS_IsMainThread());
+    NS_IF_ADDREF(mRawPtr = aPtr);
+  }
+  explicit nsMainThreadPtrHolder(already_AddRefed<T> aPtr, bool aString = true)
+    : mRawPtr(aPtr.take())
+    , mStrict(aString)
+  {
+    // Since we don't need to AddRef the pointer, this constructor is safe to
+    // call on any thread.
+  }
+
+private:
+  // We can be released on any thread.
+  ~nsMainThreadPtrHolder()
+  {
+    if (NS_IsMainThread()) {
+      NS_IF_RELEASE(mRawPtr);
+    } else if (mRawPtr) {
+      NS_ReleaseOnMainThread(dont_AddRef(mRawPtr));
+    }
+  }
+
+public:
+  T* get()
+  {
+    // Nobody should be touching the raw pointer off-main-thread.
+    if (mStrict && MOZ_UNLIKELY(!NS_IsMainThread())) {
+      NS_ERROR("Can't dereference nsMainThreadPtrHolder off main thread");
+      MOZ_CRASH();
+    }
+    return mRawPtr;
+  }
+
+  bool operator==(const nsMainThreadPtrHolder<T>& aOther) const
+  {
+    return mRawPtr == aOther.mRawPtr;
+  }
+  bool operator!() const
+  {
+    return !mRawPtr;
+  }
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(nsMainThreadPtrHolder<T>)
+
+private:
+  // Our wrapped pointer.
+  T* mRawPtr;
+
+  // Whether to strictly enforce thread invariants in this class.
+  bool mStrict;
+
+  // Copy constructor and operator= not implemented. Once constructed, the
+  // holder is immutable.
+  T& operator=(nsMainThreadPtrHolder& aOther);
+  nsMainThreadPtrHolder(const nsMainThreadPtrHolder& aOther);
+};
+
+template<class T>
+class nsMainThreadPtrHandle
+{
+  RefPtr<nsMainThreadPtrHolder<T>> mPtr;
+
+public:
+  nsMainThreadPtrHandle() : mPtr(nullptr) {}
+  MOZ_IMPLICIT nsMainThreadPtrHandle(decltype(nullptr)) : mPtr(nullptr) {}
+  explicit nsMainThreadPtrHandle(nsMainThreadPtrHolder<T>* aHolder)
+    : mPtr(aHolder)
+  {
+  }
+  explicit nsMainThreadPtrHandle(
+      already_AddRefed<nsMainThreadPtrHolder<T>> aHolder)
+    : mPtr(aHolder)
+  {
+  }
+  nsMainThreadPtrHandle(const nsMainThreadPtrHandle& aOther)
+    : mPtr(aOther.mPtr)
+  {
+  }
+  nsMainThreadPtrHandle& operator=(const nsMainThreadPtrHandle& aOther)
+  {
+    mPtr = aOther.mPtr;
+    return *this;
+  }
+  nsMainThreadPtrHandle& operator=(nsMainThreadPtrHolder<T>* aHolder)
+  {
+    mPtr = aHolder;
+    return *this;
+  }
+
+  // These all call through to nsMainThreadPtrHolder, and thus implicitly
+  // assert that we're on the main thread. Off-main-thread consumers must treat
+  // these handles as opaque.
+  T* get()
+  {
+    if (mPtr) {
+      return mPtr.get()->get();
+    }
+    return nullptr;
+  }
+  const T* get() const
+  {
+    if (mPtr) {
+      return mPtr.get()->get();
+    }
+    return nullptr;
+  }
+
+  operator T*() { return get(); }
+  T* operator->() MOZ_NO_ADDREF_RELEASE_ON_RETURN { return get(); }
+
+  // These are safe to call on other threads with appropriate external locking.
+  bool operator==(const nsMainThreadPtrHandle<T>& aOther) const
+  {
+    if (!mPtr || !aOther.mPtr) {
+      return mPtr == aOther.mPtr;
+    }
+    return *mPtr == *aOther.mPtr;
+  }
+  bool operator!=(const nsMainThreadPtrHandle<T>& aOther) const
+  {
+    return !operator==(aOther);
+  }
+  bool operator==(decltype(nullptr)) const { return mPtr == nullptr; }
+  bool operator!=(decltype(nullptr)) const { return mPtr != nullptr; }
+  bool operator!() const {
+    return !mPtr || !*mPtr;
+  }
+};
+
+namespace mozilla {
+
+template<typename T>
+using PtrHolder = nsMainThreadPtrHolder<T>;
+
+template<typename T>
+using PtrHandle = nsMainThreadPtrHandle<T>;
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/glue/nsQuickSort.cpp b/xpcom/glue/nsQuickSort.cpp
new file mode 100644
index 0000000000..f409b875e4
--- /dev/null
+++ b/xpcom/glue/nsQuickSort.cpp
@@ -0,0 +1,187 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+
+/*-
+ * Copyright (c) 1992, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/* We need this because Solaris' version of qsort is broken and
+ * causes array bounds reads.
+ */
+
+#include <stdlib.h>
+#include "nsAlgorithm.h"
+#include "nsQuickSort.h"
+
+extern "C" {
+
+#if !defined(DEBUG) && (defined(__cplusplus) || defined(__gcc))
+# ifndef INLINE
+#  define INLINE inline
+# endif
+#else
+# define INLINE
+#endif
+
+typedef int		 cmp_t(const void *, const void *, void *);
+static INLINE char	*med3(char *, char *, char *, cmp_t *, void *);
+static INLINE void	swapfunc(char *, char *, int, int);
+
+/*
+ * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
+ */
+#define swapcode(TYPE, parmi, parmj, n) { 		\
+	long i = (n) / sizeof (TYPE); 			\
+	TYPE *pi = (TYPE *) (parmi); 			\
+	TYPE *pj = (TYPE *) (parmj); 			\
+	do { 						\
+		TYPE	t = *pi;			\
+		*pi++ = *pj;				\
+		*pj++ = t;				\
+        } while (--i > 0);				\
+}
+
+#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
+	es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
+
+static INLINE void
+swapfunc(char *a, char *b, int n, int swaptype)
+{
+	if(swaptype <= 1)
+		swapcode(long, a, b, n)
+	else
+		swapcode(char, a, b, n)
+}
+
+#define swap(a, b)					\
+	if (swaptype == 0) {				\
+		long t = *(long *)(a);			\
+		*(long *)(a) = *(long *)(b);		\
+		*(long *)(b) = t;			\
+	} else						\
+		swapfunc((char *)a, (char*)b, (int)es, swaptype)
+
+#define vecswap(a, b, n) 	if ((n) > 0) swapfunc((char *)a, (char *)b, (int)n, swaptype)
+
+static INLINE char *
+med3(char *a, char *b, char *c, cmp_t* cmp, void *data)
+{
+	return cmp(a, b, data) < 0 ?
+	       (cmp(b, c, data) < 0 ? b : (cmp(a, c, data) < 0 ? c : a ))
+              :(cmp(b, c, data) > 0 ? b : (cmp(a, c, data) < 0 ? a : c ));
+}
+
+void NS_QuickSort (
+	void *a,
+	unsigned int n,
+    unsigned int es,
+	cmp_t *cmp,
+	void *data
+    )
+{
+	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
+	int d, r, swaptype;
+
+loop:	SWAPINIT(a, es);
+	/* Use insertion sort when input is small */
+	if (n < 7) {
+		for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
+			for (pl = pm; pl > (char *)a && cmp(pl - es, pl, data) > 0;
+			     pl -= es)
+				swap(pl, pl - es);
+		return;
+	}
+	/* Choose pivot */
+	pm = (char *)a + (n / 2) * es;
+	if (n > 7) {
+		pl = (char *)a;
+		pn = (char *)a + (n - 1) * es;
+		if (n > 40) {
+			d = (n / 8) * es;
+			pl = med3(pl, pl + d, pl + 2 * d, cmp, data);
+			pm = med3(pm - d, pm, pm + d, cmp, data);
+			pn = med3(pn - 2 * d, pn - d, pn, cmp, data);
+		}
+		pm = med3(pl, pm, pn, cmp, data);
+	}
+	swap(a, pm);
+	pa = pb = (char *)a + es;
+
+	pc = pd = (char *)a + (n - 1) * es;
+	/* loop invariants:
+	 * [a, pa) = pivot
+	 * [pa, pb) < pivot
+	 * [pb, pc + es) unprocessed
+	 * [pc + es, pd + es) > pivot
+	 * [pd + es, pn) = pivot
+	 */
+	for (;;) {
+		while (pb <= pc && (r = cmp(pb, a, data)) <= 0) {
+			if (r == 0) {
+				swap(pa, pb);
+				pa += es;
+			}
+			pb += es;
+		}
+		while (pb <= pc && (r = cmp(pc, a, data)) >= 0) {
+			if (r == 0) {
+				swap(pc, pd);
+				pd -= es;
+			}
+			pc -= es;
+		}
+		if (pb > pc)
+			break;
+		swap(pb, pc);
+		pb += es;
+		pc -= es;
+	}
+	/* Move pivot values */
+	pn = (char *)a + n * es;
+	r = XPCOM_MIN(pa - (char *)a, pb - pa);
+	vecswap(a, pb - r, r);
+	r = XPCOM_MIN<size_t>(pd - pc, pn - pd - es);
+	vecswap(pb, pn - r, r);
+	/* Recursively process partitioned items */
+	if ((r = pb - pa) > (int)es)
+        NS_QuickSort(a, r / es, es, cmp, data);
+	if ((r = pd - pc) > (int)es) {
+		/* Iterate rather than recurse to save stack space */
+		a = pn - r;
+		n = r / es;
+		goto loop;
+	}
+/*		NS_QuickSort(pn - r, r / es, es, cmp, data);*/
+}
+
+}
+
+#undef INLINE
+#undef swapcode
+#undef SWAPINIT
+#undef swap
+#undef vecswap
diff --git a/xpcom/glue/nsQuickSort.h b/xpcom/glue/nsQuickSort.h
new file mode 100644
index 0000000000..e8d8ed8709
--- /dev/null
+++ b/xpcom/glue/nsQuickSort.h
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/* We need this because Solaris' version of qsort is broken and
+ * causes array bounds reads.
+ */
+
+#ifndef nsQuickSort_h___
+#define nsQuickSort_h___
+
+#include "nscore.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Parameters:
+ *  1. the array to sort
+ *  2. the number of elements in the array
+ *  3. the size of each array element
+ *  4. comparison function taking two elements and parameter #5 and
+ *     returning an integer:
+ *      + less than zero if the first element should be before the second
+ *      + 0 if the order of the elements does not matter
+ *      + greater than zero if the second element should be before the first
+ *  5. extra data to pass to comparison function
+ */
+void NS_QuickSort(void*, unsigned int, unsigned int,
+                  int (*)(const void*, const void*, void*),
+                  void*);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* nsQuickSort_h___ */
diff --git a/xpcom/glue/nsRefPtrHashtable.h b/xpcom/glue/nsRefPtrHashtable.h
new file mode 100644
index 0000000000..0ff1e0181d
--- /dev/null
+++ b/xpcom/glue/nsRefPtrHashtable.h
@@ -0,0 +1,191 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsRefPtrHashtable_h__
+#define nsRefPtrHashtable_h__
+
+#include "nsBaseHashtable.h"
+#include "nsHashKeys.h"
+#include "nsAutoPtr.h"
+
+/**
+ * templated hashtable class maps keys to reference pointers.
+ * See nsBaseHashtable for complete declaration.
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param PtrType the reference-type being wrapped
+ * @see nsDataHashtable, nsClassHashtable
+ */
+template<class KeyClass, class PtrType>
+class nsRefPtrHashtable
+  : public nsBaseHashtable<KeyClass, RefPtr<PtrType>, PtrType*>
+{
+public:
+  typedef typename KeyClass::KeyType KeyType;
+  typedef PtrType* UserDataType;
+  typedef nsBaseHashtable<KeyClass, RefPtr<PtrType>, PtrType*> base_type;
+
+  nsRefPtrHashtable() {}
+  explicit nsRefPtrHashtable(uint32_t aInitLength)
+    : nsBaseHashtable<KeyClass, RefPtr<PtrType>, PtrType*>(aInitLength)
+  {
+  }
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   * @param aData This is an XPCOM getter, so aData is already_addrefed.
+   *   If the key doesn't exist, aData will be set to nullptr.
+   */
+  bool Get(KeyType aKey, UserDataType* aData) const;
+
+  /**
+   * Gets a weak reference to the hashtable entry.
+   * @param aFound If not nullptr, will be set to true if the entry is found,
+   *               to false otherwise.
+   * @return The entry, or nullptr if not found. Do not release this pointer!
+   */
+  PtrType* GetWeak(KeyType aKey, bool* aFound = nullptr) const;
+
+  // Overload Put, rather than overriding it.
+  using base_type::Put;
+
+  void Put(KeyType aKey, already_AddRefed<PtrType> aData);
+
+  MOZ_MUST_USE bool Put(KeyType aKey, already_AddRefed<PtrType> aData,
+                        const mozilla::fallible_t&);
+
+  // Overload Remove, rather than overriding it.
+  using base_type::Remove;
+
+  /**
+   * Remove the data for the associated key, swapping the current value into
+   * pData, thereby avoiding calls to AddRef and Release.
+   * @param aKey the key to remove from the hashtable
+   * @param aData This is an XPCOM getter, so aData is already_addrefed.
+   *   If the key doesn't exist, aData will be set to nullptr. Must be non-null.
+   */
+  bool Remove(KeyType aKey, UserDataType* aData);
+};
+
+template<typename K, typename T>
+inline void
+ImplCycleCollectionUnlink(nsRefPtrHashtable<K, T>& aField)
+{
+  aField.Clear();
+}
+
+template<typename K, typename T>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsRefPtrHashtable<K, T>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  for (auto iter = aField.ConstIter(); !iter.Done(); iter.Next()) {
+    CycleCollectionNoteChild(aCallback, iter.UserData(), aName, aFlags);
+  }
+}
+
+//
+// nsRefPtrHashtable definitions
+//
+
+template<class KeyClass, class PtrType>
+bool
+nsRefPtrHashtable<KeyClass, PtrType>::Get(KeyType aKey,
+                                          UserDataType* aRefPtr) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aRefPtr) {
+      *aRefPtr = ent->mData;
+
+      NS_IF_ADDREF(*aRefPtr);
+    }
+
+    return true;
+  }
+
+  // if the key doesn't exist, set *aRefPtr to null
+  // so that it is a valid XPCOM getter
+  if (aRefPtr) {
+    *aRefPtr = nullptr;
+  }
+
+  return false;
+}
+
+template<class KeyClass, class PtrType>
+PtrType*
+nsRefPtrHashtable<KeyClass, PtrType>::GetWeak(KeyType aKey, bool* aFound) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aFound) {
+      *aFound = true;
+    }
+
+    return ent->mData;
+  }
+
+  // Key does not exist, return nullptr and set aFound to false
+  if (aFound) {
+    *aFound = false;
+  }
+
+  return nullptr;
+}
+
+template<class KeyClass, class PtrType>
+void
+nsRefPtrHashtable<KeyClass, PtrType>::Put(KeyType aKey,
+                                          already_AddRefed<PtrType> aData)
+{
+  if (!Put(aKey, mozilla::Move(aData), mozilla::fallible)) {
+    NS_ABORT_OOM(this->mTable.EntrySize() * this->mTable.EntryCount());
+  }
+}
+
+template<class KeyClass, class PtrType>
+bool
+nsRefPtrHashtable<KeyClass, PtrType>::Put(KeyType aKey,
+                                          already_AddRefed<PtrType> aData,
+                                          const mozilla::fallible_t&)
+{
+  typename base_type::EntryType* ent = this->PutEntry(aKey);
+
+  if (!ent) {
+    return false;
+  }
+
+  ent->mData = aData;
+
+  return true;
+}
+
+template<class KeyClass, class PtrType>
+bool
+nsRefPtrHashtable<KeyClass, PtrType>::Remove(KeyType aKey,
+                                             UserDataType* aRefPtr)
+{
+  MOZ_ASSERT(aRefPtr);
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    ent->mData.forget(aRefPtr);
+    this->Remove(aKey);
+    return true;
+  }
+
+  // If the key doesn't exist, set *aRefPtr to null
+  // so that it is a valid XPCOM getter.
+  *aRefPtr = nullptr;
+  return false;
+}
+
+#endif // nsRefPtrHashtable_h__
diff --git a/xpcom/glue/nsServiceManagerUtils.h b/xpcom/glue/nsServiceManagerUtils.h
new file mode 100644
index 0000000000..d1ea408a2a
--- /dev/null
+++ b/xpcom/glue/nsServiceManagerUtils.h
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsServiceManagerUtils_h__
+#define nsServiceManagerUtils_h__
+
+#include "nsIServiceManager.h"
+#include "nsCOMPtr.h"
+
+inline const nsGetServiceByCID
+do_GetService(const nsCID& aCID)
+{
+  return nsGetServiceByCID(aCID);
+}
+
+inline const nsGetServiceByCIDWithError
+do_GetService(const nsCID& aCID, nsresult* aError)
+{
+  return nsGetServiceByCIDWithError(aCID, aError);
+}
+
+inline const nsGetServiceByContractID
+do_GetService(const char* aContractID)
+{
+  return nsGetServiceByContractID(aContractID);
+}
+
+inline const nsGetServiceByContractIDWithError
+do_GetService(const char* aContractID, nsresult* aError)
+{
+  return nsGetServiceByContractIDWithError(aContractID, aError);
+}
+
+class MOZ_STACK_CLASS nsGetServiceFromCategory final : public nsCOMPtr_helper
+{
+public:
+  nsGetServiceFromCategory(const char* aCategory, const char* aEntry,
+                           nsresult* aErrorPtr)
+    : mCategory(aCategory)
+    , mEntry(aEntry)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const
+    override;
+protected:
+  const char*                 mCategory;
+  const char*                 mEntry;
+  nsresult*                   mErrorPtr;
+};
+
+inline const nsGetServiceFromCategory
+do_GetServiceFromCategory(const char* aCategory, const char* aEntry,
+                          nsresult* aError = 0)
+{
+  return nsGetServiceFromCategory(aCategory, aEntry, aError);
+}
+
+nsresult CallGetService(const nsCID& aClass, const nsIID& aIID, void** aResult);
+
+nsresult CallGetService(const char* aContractID, const nsIID& aIID,
+                        void** aResult);
+
+// type-safe shortcuts for calling |GetService|
+template<class DestinationType>
+inline nsresult
+CallGetService(const nsCID& aClass,
+               DestinationType** aDestination)
+{
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallGetService(aClass,
+                        NS_GET_TEMPLATE_IID(DestinationType),
+                        reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallGetService(const char* aContractID,
+               DestinationType** aDestination)
+{
+  NS_PRECONDITION(aContractID, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallGetService(aContractID,
+                        NS_GET_TEMPLATE_IID(DestinationType),
+                        reinterpret_cast<void**>(aDestination));
+}
+
+#endif
diff --git a/xpcom/glue/nsStringAPI.cpp b/xpcom/glue/nsStringAPI.cpp
new file mode 100644
index 0000000000..e5114a149a
--- /dev/null
+++ b/xpcom/glue/nsStringAPI.cpp
@@ -0,0 +1,1304 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nscore.h"
+#include "nsCRTGlue.h"
+#include "prprf.h"
+#include "nsStringAPI.h"
+#include "nsXPCOMStrings.h"
+#include "nsDebug.h"
+
+#include "mozilla/Sprintf.h"
+
+#include <stdio.h>
+
+// nsAString
+
+uint32_t
+nsAString::BeginReading(const char_type** aBegin, const char_type** aEnd) const
+{
+  uint32_t len = NS_StringGetData(*this, aBegin);
+  if (aEnd) {
+    *aEnd = *aBegin + len;
+  }
+
+  return len;
+}
+
+const nsAString::char_type*
+nsAString::BeginReading() const
+{
+  const char_type* data;
+  NS_StringGetData(*this, &data);
+  return data;
+}
+
+const nsAString::char_type*
+nsAString::EndReading() const
+{
+  const char_type* data;
+  uint32_t len = NS_StringGetData(*this, &data);
+  return data + len;
+}
+
+uint32_t
+nsAString::BeginWriting(char_type** aBegin, char_type** aEnd, uint32_t aNewSize)
+{
+  uint32_t len = NS_StringGetMutableData(*this, aNewSize, aBegin);
+  if (aEnd) {
+    *aEnd = *aBegin + len;
+  }
+
+  return len;
+}
+
+nsAString::char_type*
+nsAString::BeginWriting(uint32_t aLen)
+{
+  char_type* data;
+  NS_StringGetMutableData(*this, aLen, &data);
+  return data;
+}
+
+nsAString::char_type*
+nsAString::EndWriting()
+{
+  char_type* data;
+  uint32_t len = NS_StringGetMutableData(*this, UINT32_MAX, &data);
+  return data + len;
+}
+
+bool
+nsAString::SetLength(uint32_t aLen)
+{
+  char_type* data;
+  NS_StringGetMutableData(*this, aLen, &data);
+  return data != nullptr;
+}
+
+void
+nsAString::AssignLiteral(const char* aStr)
+{
+  uint32_t len = strlen(aStr);
+  char16_t* buf = BeginWriting(len);
+  if (!buf) {
+    return;
+  }
+
+  for (; *aStr; ++aStr, ++buf) {
+    *buf = *aStr;
+  }
+}
+
+void
+nsAString::AppendLiteral(const char* aASCIIStr)
+{
+  uint32_t appendLen = strlen(aASCIIStr);
+
+  uint32_t thisLen = Length();
+  char16_t* begin;
+  char16_t* end;
+  BeginWriting(&begin, &end, appendLen + thisLen);
+  if (!begin) {
+    return;
+  }
+
+  for (begin += thisLen; begin < end; ++begin, ++aASCIIStr) {
+    *begin = *aASCIIStr;
+  }
+}
+
+void
+nsAString::StripChars(const char* aSet)
+{
+  nsString copy(*this);
+
+  const char_type* source;
+  const char_type* sourceEnd;
+  copy.BeginReading(&source, &sourceEnd);
+
+  char_type* dest;
+  BeginWriting(&dest);
+  if (!dest) {
+    return;
+  }
+
+  char_type* curDest = dest;
+
+  for (; source < sourceEnd; ++source) {
+    const char* test;
+    for (test = aSet; *test; ++test) {
+      if (*source == char_type(*test)) {
+        break;
+      }
+    }
+
+    if (!*test) {
+      // not stripped, copy this char
+      *curDest = *source;
+      ++curDest;
+    }
+  }
+
+  SetLength(curDest - dest);
+}
+
+void
+nsAString::Trim(const char* aSet, bool aLeading, bool aTrailing)
+{
+  NS_ASSERTION(aLeading || aTrailing, "Ineffective Trim");
+
+  const char16_t* start;
+  const char16_t* end;
+  uint32_t cutLen;
+
+  if (aLeading) {
+    BeginReading(&start, &end);
+    for (cutLen = 0; start < end; ++start, ++cutLen) {
+      const char* test;
+      for (test = aSet; *test; ++test) {
+        if (*test == *start) {
+          break;
+        }
+      }
+      if (!*test) {
+        break;
+      }
+    }
+    if (cutLen) {
+      NS_StringCutData(*this, 0, cutLen);
+    }
+  }
+  if (aTrailing) {
+    uint32_t len = BeginReading(&start, &end);
+    --end;
+    for (cutLen = 0; end >= start; --end, ++cutLen) {
+      const char* test;
+      for (test = aSet; *test; ++test) {
+        if (*test == *end) {
+          break;
+        }
+      }
+      if (!*test) {
+        break;
+      }
+    }
+    if (cutLen) {
+      NS_StringCutData(*this, len - cutLen, cutLen);
+    }
+  }
+}
+
+int32_t
+nsAString::DefaultComparator(const char_type* aStrA, const char_type* aStrB,
+                             uint32_t aLen)
+{
+  for (const char_type* end = aStrA + aLen; aStrA < end; ++aStrA, ++aStrB) {
+    if (*aStrA == *aStrB) {
+      continue;
+    }
+
+    return *aStrA < *aStrB ? -1 : 1;
+  }
+
+  return 0;
+}
+
+int32_t
+nsAString::Compare(const char_type* aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  uint32_t selflen = NS_StringGetData(*this, &cself);
+  uint32_t otherlen = NS_strlen(aOther);
+  uint32_t comparelen = selflen <= otherlen ? selflen : otherlen;
+
+  int32_t result = aComparator(cself, aOther, comparelen);
+  if (result == 0) {
+    if (selflen < otherlen) {
+      return -1;
+    } else if (selflen > otherlen) {
+      return 1;
+    }
+  }
+  return result;
+}
+
+int32_t
+nsAString::Compare(const self_type& aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  const char_type* cother;
+  uint32_t selflen = NS_StringGetData(*this, &cself);
+  uint32_t otherlen = NS_StringGetData(aOther, &cother);
+  uint32_t comparelen = selflen <= otherlen ? selflen : otherlen;
+
+  int32_t result = aComparator(cself, cother, comparelen);
+  if (result == 0) {
+    if (selflen < otherlen) {
+      return -1;
+    } else if (selflen > otherlen) {
+      return 1;
+    }
+  }
+  return result;
+}
+
+bool
+nsAString::Equals(const char_type* aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  uint32_t selflen = NS_StringGetData(*this, &cself);
+  uint32_t otherlen = NS_strlen(aOther);
+
+  if (selflen != otherlen) {
+    return false;
+  }
+
+  return aComparator(cself, aOther, selflen) == 0;
+}
+
+bool
+nsAString::Equals(const self_type& aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  const char_type* cother;
+  uint32_t selflen = NS_StringGetData(*this, &cself);
+  uint32_t otherlen = NS_StringGetData(aOther, &cother);
+
+  if (selflen != otherlen) {
+    return false;
+  }
+
+  return aComparator(cself, cother, selflen) == 0;
+}
+
+bool
+nsAString::EqualsLiteral(const char* aASCIIString) const
+{
+  const char16_t* begin;
+  const char16_t* end;
+  BeginReading(&begin, &end);
+
+  for (; begin < end; ++begin, ++aASCIIString) {
+    if (!*aASCIIString || !NS_IsAscii(*begin) ||
+        (char)*begin != *aASCIIString) {
+      return false;
+    }
+  }
+
+  return *aASCIIString == '\0';
+}
+
+bool
+nsAString::LowerCaseEqualsLiteral(const char* aASCIIString) const
+{
+  const char16_t* begin;
+  const char16_t* end;
+  BeginReading(&begin, &end);
+
+  for (; begin < end; ++begin, ++aASCIIString) {
+    if (!*aASCIIString || !NS_IsAscii(*begin) ||
+        NS_ToLower((char)*begin) != *aASCIIString) {
+      return false;
+    }
+  }
+
+  return *aASCIIString == '\0';
+}
+
+int32_t
+nsAString::Find(const self_type& aStr, uint32_t aOffset,
+                ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  if (aOffset > selflen) {
+    return -1;
+  }
+
+  const char_type* other;
+  uint32_t otherlen = aStr.BeginReading(&other);
+
+  if (otherlen > selflen - aOffset) {
+    return -1;
+  }
+
+  // We want to stop searching otherlen characters before the end of the string
+  end -= otherlen;
+
+  for (const char_type* cur = begin + aOffset; cur <= end; ++cur) {
+    if (!aComparator(cur, other, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+static bool
+ns_strnmatch(const char16_t* aStr, const char* aSubstring, uint32_t aLen)
+{
+  for (; aLen; ++aStr, ++aSubstring, --aLen) {
+    if (!NS_IsAscii(*aStr)) {
+      return false;
+    }
+
+    if ((char)*aStr != *aSubstring) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+static bool
+ns_strnimatch(const char16_t* aStr, const char* aSubstring, uint32_t aLen)
+{
+  for (; aLen; ++aStr, ++aSubstring, --aLen) {
+    if (!NS_IsAscii(*aStr)) {
+      return false;
+    }
+
+    if (NS_ToLower((char)*aStr) != NS_ToLower(*aSubstring)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+int32_t
+nsAString::Find(const char* aStr, uint32_t aOffset, bool aIgnoreCase) const
+{
+  bool (*match)(const char16_t*, const char*, uint32_t) =
+    aIgnoreCase ? ns_strnimatch : ns_strnmatch;
+
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  if (aOffset > selflen) {
+    return -1;
+  }
+
+  uint32_t otherlen = strlen(aStr);
+
+  if (otherlen > selflen - aOffset) {
+    return -1;
+  }
+
+  // We want to stop searching otherlen characters before the end of the string
+  end -= otherlen;
+
+  for (const char_type* cur = begin + aOffset; cur <= end; ++cur) {
+    if (match(cur, aStr, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsAString::RFind(const self_type& aStr, int32_t aOffset,
+                 ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  const char_type* other;
+  uint32_t otherlen = aStr.BeginReading(&other);
+
+  if (selflen < otherlen) {
+    return -1;
+  }
+
+  if (aOffset < 0 || uint32_t(aOffset) > (selflen - otherlen)) {
+    end -= otherlen;
+  } else {
+    end = begin + aOffset;
+  }
+
+  for (const char_type* cur = end; cur >= begin; --cur) {
+    if (!aComparator(cur, other, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsAString::RFind(const char* aStr, int32_t aOffset, bool aIgnoreCase) const
+{
+  bool (*match)(const char16_t*, const char*, uint32_t) =
+    aIgnoreCase ? ns_strnimatch : ns_strnmatch;
+
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+  uint32_t otherlen = strlen(aStr);
+
+  if (selflen < otherlen) {
+    return -1;
+  }
+
+  if (aOffset < 0 || uint32_t(aOffset) > (selflen - otherlen)) {
+    end -= otherlen;
+  } else {
+    end = begin + aOffset;
+  }
+
+  for (const char_type* cur = end; cur >= begin; --cur) {
+    if (match(cur, aStr, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsAString::FindChar(char_type aChar, uint32_t aOffset) const
+{
+  const char_type* start;
+  const char_type* end;
+  uint32_t len = BeginReading(&start, &end);
+  if (aOffset > len) {
+    return -1;
+  }
+
+  const char_type* cur;
+
+  for (cur = start + aOffset; cur < end; ++cur) {
+    if (*cur == aChar) {
+      return cur - start;
+    }
+  }
+
+  return -1;
+}
+
+int32_t
+nsAString::RFindChar(char_type aChar) const
+{
+  const char16_t* start;
+  const char16_t* end;
+  BeginReading(&start, &end);
+
+  do {
+    --end;
+
+    if (*end == aChar) {
+      return end - start;
+    }
+
+  } while (end >= start);
+
+  return -1;
+}
+
+void
+nsAString::AppendInt(int aInt, int32_t aRadix)
+{
+  const char* fmt;
+  switch (aRadix) {
+    case 8:
+      fmt = "%o";
+      break;
+
+    case 10:
+      fmt = "%d";
+      break;
+
+    case 16:
+      fmt = "%x";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix");
+      fmt = "";
+  }
+
+  char buf[20];
+  int len = SprintfLiteral(buf, fmt, aInt);
+  Append(NS_ConvertASCIItoUTF16(buf, len));
+}
+
+// Strings
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+int32_t
+nsAString::ToInteger(nsresult* aErrorCode, uint32_t aRadix) const
+{
+  NS_ConvertUTF16toUTF8 narrow(*this);
+
+  const char* fmt;
+  switch (aRadix) {
+    case 10:
+      fmt = "%i";
+      break;
+
+    case 16:
+      fmt = "%x";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix!");
+      *aErrorCode = NS_ERROR_INVALID_ARG;
+      return 0;
+  }
+
+  int32_t result = 0;
+  if (PR_sscanf(narrow.get(), fmt, &result) == 1) {
+    *aErrorCode = NS_OK;
+  } else {
+    *aErrorCode = NS_ERROR_FAILURE;
+  }
+
+  return result;
+}
+
+int64_t
+nsAString::ToInteger64(nsresult* aErrorCode, uint32_t aRadix) const
+{
+  NS_ConvertUTF16toUTF8 narrow(*this);
+
+  const char* fmt;
+  switch (aRadix) {
+    case 10:
+      fmt = "%lli";
+      break;
+
+    case 16:
+      fmt = "%llx";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix!");
+      *aErrorCode = NS_ERROR_INVALID_ARG;
+      return 0;
+  }
+
+  int64_t result = 0;
+  if (PR_sscanf(narrow.get(), fmt, &result) == 1) {
+    *aErrorCode = NS_OK;
+  } else {
+    *aErrorCode = NS_ERROR_FAILURE;
+  }
+
+  return result;
+}
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+// nsACString
+
+uint32_t
+nsACString::BeginReading(const char_type** aBegin, const char_type** aEnd) const
+{
+  uint32_t len = NS_CStringGetData(*this, aBegin);
+  if (aEnd) {
+    *aEnd = *aBegin + len;
+  }
+
+  return len;
+}
+
+const nsACString::char_type*
+nsACString::BeginReading() const
+{
+  const char_type* data;
+  NS_CStringGetData(*this, &data);
+  return data;
+}
+
+const nsACString::char_type*
+nsACString::EndReading() const
+{
+  const char_type* data;
+  uint32_t len = NS_CStringGetData(*this, &data);
+  return data + len;
+}
+
+uint32_t
+nsACString::BeginWriting(char_type** aBegin, char_type** aEnd,
+                         uint32_t aNewSize)
+{
+  uint32_t len = NS_CStringGetMutableData(*this, aNewSize, aBegin);
+  if (aEnd) {
+    *aEnd = *aBegin + len;
+  }
+
+  return len;
+}
+
+nsACString::char_type*
+nsACString::BeginWriting(uint32_t aLen)
+{
+  char_type* data;
+  NS_CStringGetMutableData(*this, aLen, &data);
+  return data;
+}
+
+nsACString::char_type*
+nsACString::EndWriting()
+{
+  char_type* data;
+  uint32_t len = NS_CStringGetMutableData(*this, UINT32_MAX, &data);
+  return data + len;
+}
+
+bool
+nsACString::SetLength(uint32_t aLen)
+{
+  char_type* data;
+  NS_CStringGetMutableData(*this, aLen, &data);
+  return data != nullptr;
+}
+
+void
+nsACString::StripChars(const char* aSet)
+{
+  nsCString copy(*this);
+
+  const char_type* source;
+  const char_type* sourceEnd;
+  copy.BeginReading(&source, &sourceEnd);
+
+  char_type* dest;
+  BeginWriting(&dest);
+  if (!dest) {
+    return;
+  }
+
+  char_type* curDest = dest;
+
+  for (; source < sourceEnd; ++source) {
+    const char* test;
+    for (test = aSet; *test; ++test) {
+      if (*source == char_type(*test)) {
+        break;
+      }
+    }
+
+    if (!*test) {
+      // not stripped, copy this char
+      *curDest = *source;
+      ++curDest;
+    }
+  }
+
+  SetLength(curDest - dest);
+}
+
+void
+nsACString::Trim(const char* aSet, bool aLeading, bool aTrailing)
+{
+  NS_ASSERTION(aLeading || aTrailing, "Ineffective Trim");
+
+  const char* start;
+  const char* end;
+  uint32_t cutLen;
+
+  if (aLeading) {
+    BeginReading(&start, &end);
+    for (cutLen = 0; start < end; ++start, ++cutLen) {
+      const char* test;
+      for (test = aSet; *test; ++test) {
+        if (*test == *start) {
+          break;
+        }
+      }
+      if (!*test) {
+        break;
+      }
+    }
+    if (cutLen) {
+      NS_CStringCutData(*this, 0, cutLen);
+    }
+  }
+  if (aTrailing) {
+    uint32_t len = BeginReading(&start, &end);
+    --end;
+    for (cutLen = 0; end >= start; --end, ++cutLen) {
+      const char* test;
+      for (test = aSet; *test; ++test) {
+        if (*test == *end) {
+          break;
+        }
+      }
+      if (!*test) {
+        break;
+      }
+    }
+    if (cutLen) {
+      NS_CStringCutData(*this, len - cutLen, cutLen);
+    }
+  }
+}
+
+int32_t
+nsACString::DefaultComparator(const char_type* aStrA, const char_type* aStrB,
+                              uint32_t aLen)
+{
+  return memcmp(aStrA, aStrB, aLen);
+}
+
+int32_t
+nsACString::Compare(const char_type* aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  uint32_t selflen = NS_CStringGetData(*this, &cself);
+  uint32_t otherlen = strlen(aOther);
+  uint32_t comparelen = selflen <= otherlen ? selflen : otherlen;
+
+  int32_t result = aComparator(cself, aOther, comparelen);
+  if (result == 0) {
+    if (selflen < otherlen) {
+      return -1;
+    } else if (selflen > otherlen) {
+      return 1;
+    }
+  }
+  return result;
+}
+
+int32_t
+nsACString::Compare(const self_type& aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  const char_type* cother;
+  uint32_t selflen = NS_CStringGetData(*this, &cself);
+  uint32_t otherlen = NS_CStringGetData(aOther, &cother);
+  uint32_t comparelen = selflen <= otherlen ? selflen : otherlen;
+
+  int32_t result = aComparator(cself, cother, comparelen);
+  if (result == 0) {
+    if (selflen < otherlen) {
+      return -1;
+    } else if (selflen > otherlen) {
+      return 1;
+    }
+  }
+  return result;
+}
+
+bool
+nsACString::Equals(const char_type* aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  uint32_t selflen = NS_CStringGetData(*this, &cself);
+  uint32_t otherlen = strlen(aOther);
+
+  if (selflen != otherlen) {
+    return false;
+  }
+
+  return aComparator(cself, aOther, selflen) == 0;
+}
+
+bool
+nsACString::Equals(const self_type& aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  const char_type* cother;
+  uint32_t selflen = NS_CStringGetData(*this, &cself);
+  uint32_t otherlen = NS_CStringGetData(aOther, &cother);
+
+  if (selflen != otherlen) {
+    return false;
+  }
+
+  return aComparator(cself, cother, selflen) == 0;
+}
+
+int32_t
+nsACString::Find(const self_type& aStr, uint32_t aOffset,
+                 ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  if (aOffset > selflen) {
+    return -1;
+  }
+
+  const char_type* other;
+  uint32_t otherlen = aStr.BeginReading(&other);
+
+  if (otherlen > selflen - aOffset) {
+    return -1;
+  }
+
+  // We want to stop searching otherlen characters before the end of the string
+  end -= otherlen;
+
+  for (const char_type* cur = begin + aOffset; cur <= end; ++cur) {
+    if (!aComparator(cur, other, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsACString::Find(const char_type* aStr, ComparatorFunc aComparator) const
+{
+  return Find(aStr, strlen(aStr), aComparator);
+}
+
+int32_t
+nsACString::Find(const char_type* aStr, uint32_t aLen,
+                 ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  if (aLen == 0) {
+    NS_WARNING("Searching for zero-length string.");
+    return -1;
+  }
+
+  if (aLen > selflen) {
+    return -1;
+  }
+
+  // We want to stop searching otherlen characters before the end of the string
+  end -= aLen;
+
+  for (const char_type* cur = begin; cur <= end; ++cur) {
+    if (!aComparator(cur, aStr, aLen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsACString::RFind(const self_type& aStr, int32_t aOffset,
+                  ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  const char_type* other;
+  uint32_t otherlen = aStr.BeginReading(&other);
+
+  if (selflen < otherlen) {
+    return -1;
+  }
+
+  if (aOffset < 0 || uint32_t(aOffset) > (selflen - otherlen)) {
+    end -= otherlen;
+  } else {
+    end = begin + aOffset;
+  }
+
+  for (const char_type* cur = end; cur >= begin; --cur) {
+    if (!aComparator(cur, other, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsACString::RFind(const char_type* aStr, ComparatorFunc aComparator) const
+{
+  return RFind(aStr, strlen(aStr), aComparator);
+}
+
+int32_t
+nsACString::RFind(const char_type* aStr, int32_t aLen,
+                  ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  if (aLen <= 0) {
+    NS_WARNING("Searching for zero-length string.");
+    return -1;
+  }
+
+  if (uint32_t(aLen) > selflen) {
+    return -1;
+  }
+
+  // We want to start searching otherlen characters before the end of the string
+  end -= aLen;
+
+  for (const char_type* cur = end; cur >= begin; --cur) {
+    if (!aComparator(cur, aStr, aLen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsACString::FindChar(char_type aChar, uint32_t aOffset) const
+{
+  const char_type* start;
+  const char_type* end;
+  uint32_t len = BeginReading(&start, &end);
+  if (aOffset > len) {
+    return -1;
+  }
+
+  const char_type* cur;
+
+  for (cur = start + aOffset; cur < end; ++cur) {
+    if (*cur == aChar) {
+      return cur - start;
+    }
+  }
+
+  return -1;
+}
+
+int32_t
+nsACString::RFindChar(char_type aChar) const
+{
+  const char* start;
+  const char* end;
+  BeginReading(&start, &end);
+
+  for (; end >= start; --end) {
+    if (*end == aChar) {
+      return end - start;
+    }
+  }
+
+  return -1;
+}
+
+void
+nsACString::AppendInt(int aInt, int32_t aRadix)
+{
+  const char* fmt;
+  switch (aRadix) {
+    case 8:
+      fmt = "%o";
+      break;
+
+    case 10:
+      fmt = "%d";
+      break;
+
+    case 16:
+      fmt = "%x";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix");
+      fmt = "";
+  }
+
+  char buf[20];
+  int len = SprintfLiteral(buf, fmt, aInt);
+  Append(buf, len);
+}
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+int32_t
+nsACString::ToInteger(nsresult* aErrorCode, uint32_t aRadix) const
+{
+  const char* fmt;
+  switch (aRadix) {
+    case 10:
+      fmt = "%i";
+      break;
+
+    case 16:
+      fmt = "%x";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix!");
+      *aErrorCode = NS_ERROR_INVALID_ARG;
+      return 0;
+  }
+
+  int32_t result = 0;
+  if (PR_sscanf(nsCString(*this).get(), fmt, &result) == 1) {
+    *aErrorCode = NS_OK;
+  } else {
+    *aErrorCode = NS_ERROR_FAILURE;
+  }
+
+  return result;
+}
+
+int64_t
+nsACString::ToInteger64(nsresult* aErrorCode, uint32_t aRadix) const
+{
+  const char* fmt;
+  switch (aRadix) {
+    case 10:
+      fmt = "%lli";
+      break;
+
+    case 16:
+      fmt = "%llx";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix!");
+      *aErrorCode = NS_ERROR_INVALID_ARG;
+      return 0;
+  }
+
+  int64_t result = 0;
+  if (PR_sscanf(nsCString(*this).get(), fmt, &result) == 1) {
+    *aErrorCode = NS_OK;
+  } else {
+    *aErrorCode = NS_ERROR_FAILURE;
+  }
+
+  return result;
+}
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+// Substrings
+
+nsDependentSubstring::nsDependentSubstring(const abstract_string_type& aStr,
+                                           uint32_t aStartPos)
+{
+  const char16_t* data;
+  uint32_t len = NS_StringGetData(aStr, &data);
+
+  if (aStartPos > len) {
+    aStartPos = len;
+  }
+
+  NS_StringContainerInit2(*this, data + aStartPos, len - aStartPos,
+                          NS_STRING_CONTAINER_INIT_DEPEND |
+                          NS_STRING_CONTAINER_INIT_SUBSTRING);
+}
+
+nsDependentSubstring::nsDependentSubstring(const abstract_string_type& aStr,
+                                           uint32_t aStartPos,
+                                           uint32_t aLength)
+{
+  const char16_t* data;
+  uint32_t len = NS_StringGetData(aStr, &data);
+
+  if (aStartPos > len) {
+    aStartPos = len;
+  }
+
+  if (aStartPos + aLength > len) {
+    aLength = len - aStartPos;
+  }
+
+  NS_StringContainerInit2(*this, data + aStartPos, aLength,
+                          NS_STRING_CONTAINER_INIT_DEPEND |
+                            NS_STRING_CONTAINER_INIT_SUBSTRING);
+}
+
+nsDependentCSubstring::nsDependentCSubstring(const abstract_string_type& aStr,
+                                             uint32_t aStartPos)
+{
+  const char* data;
+  uint32_t len = NS_CStringGetData(aStr, &data);
+
+  if (aStartPos > len) {
+    aStartPos = len;
+  }
+
+  NS_CStringContainerInit2(*this, data + aStartPos, len - aStartPos,
+                           NS_CSTRING_CONTAINER_INIT_DEPEND |
+                           NS_CSTRING_CONTAINER_INIT_SUBSTRING);
+}
+
+nsDependentCSubstring::nsDependentCSubstring(const abstract_string_type& aStr,
+                                             uint32_t aStartPos,
+                                             uint32_t aLength)
+{
+  const char* data;
+  uint32_t len = NS_CStringGetData(aStr, &data);
+
+  if (aStartPos > len) {
+    aStartPos = len;
+  }
+
+  if (aStartPos + aLength > len) {
+    aLength = len - aStartPos;
+  }
+
+  NS_CStringContainerInit2(*this, data + aStartPos, aLength,
+                           NS_CSTRING_CONTAINER_INIT_DEPEND |
+                           NS_CSTRING_CONTAINER_INIT_SUBSTRING);
+}
+
+// Utils
+
+char*
+ToNewUTF8String(const nsAString& aSource)
+{
+  nsCString temp;
+  CopyUTF16toUTF8(aSource, temp);
+  return NS_CStringCloneData(temp);
+}
+
+void
+CompressWhitespace(nsAString& aString)
+{
+  char16_t* start;
+  uint32_t len = NS_StringGetMutableData(aString, UINT32_MAX, &start);
+  char16_t* end = start + len;
+  char16_t* from = start;
+  char16_t* to = start;
+
+  // Skip any leading whitespace
+  while (from < end && NS_IsAsciiWhitespace(*from)) {
+    from++;
+  }
+
+  while (from < end) {
+    char16_t theChar = *from++;
+
+    if (NS_IsAsciiWhitespace(theChar)) {
+      // We found a whitespace char, so skip over any more
+      while (from < end && NS_IsAsciiWhitespace(*from)) {
+        from++;
+      }
+
+      // Turn all whitespace into spaces
+      theChar = ' ';
+    }
+
+    *to++ = theChar;
+  }
+
+  // Drop any trailing space
+  if (to > start && to[-1] == ' ') {
+    to--;
+  }
+
+  // Re-terminate the string
+  *to = '\0';
+
+  // Set the new length
+  aString.SetLength(to - start);
+}
+
+uint32_t
+ToLowerCase(nsACString& aStr)
+{
+  char* begin;
+  char* end;
+  uint32_t len = aStr.BeginWriting(&begin, &end);
+
+  for (; begin < end; ++begin) {
+    *begin = NS_ToLower(*begin);
+  }
+
+  return len;
+}
+
+uint32_t
+ToUpperCase(nsACString& aStr)
+{
+  char* begin;
+  char* end;
+  uint32_t len = aStr.BeginWriting(&begin, &end);
+
+  for (; begin < end; ++begin) {
+    *begin = NS_ToUpper(*begin);
+  }
+
+  return len;
+}
+
+uint32_t
+ToLowerCase(const nsACString& aSrc, nsACString& aDest)
+{
+  const char* begin;
+  const char* end;
+  uint32_t len = aSrc.BeginReading(&begin, &end);
+
+  char* dest;
+  NS_CStringGetMutableData(aDest, len, &dest);
+
+  for (; begin < end; ++begin, ++dest) {
+    *dest = NS_ToLower(*begin);
+  }
+
+  return len;
+}
+
+uint32_t
+ToUpperCase(const nsACString& aSrc, nsACString& aDest)
+{
+  const char* begin;
+  const char* end;
+  uint32_t len = aSrc.BeginReading(&begin, &end);
+
+  char* dest;
+  NS_CStringGetMutableData(aDest, len, &dest);
+
+  for (; begin < end; ++begin, ++dest) {
+    *dest = NS_ToUpper(*begin);
+  }
+
+  return len;
+}
+
+int32_t
+CaseInsensitiveCompare(const char* aStrA, const char* aStrB,
+                       uint32_t aLen)
+{
+  for (const char* aend = aStrA + aLen; aStrA < aend; ++aStrA, ++aStrB) {
+    char la = NS_ToLower(*aStrA);
+    char lb = NS_ToLower(*aStrB);
+
+    if (la == lb) {
+      continue;
+    }
+
+    return la < lb ? -1 : 1;
+  }
+
+  return 0;
+}
+
+bool
+ParseString(const nsACString& aSource, char aDelimiter,
+            nsTArray<nsCString>& aArray)
+{
+  int32_t start = 0;
+  int32_t end = aSource.Length();
+
+  uint32_t oldLength = aArray.Length();
+
+  for (;;) {
+    int32_t delimiter = aSource.FindChar(aDelimiter, start);
+    if (delimiter < 0) {
+      delimiter = end;
+    }
+
+    if (delimiter != start) {
+      if (!aArray.AppendElement(Substring(aSource, start, delimiter - start))) {
+        aArray.RemoveElementsAt(oldLength, aArray.Length() - oldLength);
+        return false;
+      }
+    }
+
+    if (delimiter == end) {
+      break;
+    }
+    start = ++delimiter;
+    if (start == end) {
+      break;
+    }
+  }
+
+  return true;
+}
diff --git a/xpcom/glue/nsStringAPI.h b/xpcom/glue/nsStringAPI.h
new file mode 100644
index 0000000000..d5e3686957
--- /dev/null
+++ b/xpcom/glue/nsStringAPI.h
@@ -0,0 +1,1596 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * This header provides wrapper classes around the frozen string API
+ * which are roughly equivalent to the internal string classes.
+ */
+
+#ifdef MOZILLA_INTERNAL_API
+#error nsStringAPI.h is only usable from non-MOZILLA_INTERNAL_API code!
+#endif
+
+#ifndef nsStringAPI_h__
+#define nsStringAPI_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Char16.h"
+
+#include "nsXPCOMStrings.h"
+#include "nsISupportsImpl.h"
+#include "mozilla/Logging.h"
+#include "nsTArray.h"
+
+/**
+ * Comparison function for use with nsACString::Equals
+ */
+NS_HIDDEN_(int32_t) CaseInsensitiveCompare(const char* aStrA, const char* aStrB,
+                                           uint32_t aLength);
+
+class nsAString
+{
+public:
+  typedef char16_t  char_type;
+  typedef nsAString self_type;
+  typedef uint32_t  size_type;
+  typedef uint32_t  index_type;
+
+  /**
+   * Returns the length, beginning, and end of a string in one operation.
+   */
+  NS_HIDDEN_(uint32_t) BeginReading(const char_type** aBegin,
+                                    const char_type** aEnd = nullptr) const;
+
+  NS_HIDDEN_(const char_type*) BeginReading() const;
+  NS_HIDDEN_(const char_type*) EndReading() const;
+
+  NS_HIDDEN_(char_type) CharAt(uint32_t aPos) const
+  {
+    NS_ASSERTION(aPos < Length(), "Out of bounds");
+    return BeginReading()[aPos];
+  }
+  NS_HIDDEN_(char_type) operator [](uint32_t aPos) const
+  {
+    return CharAt(aPos);
+  }
+  NS_HIDDEN_(char_type) First() const
+  {
+    return CharAt(0);
+  }
+  NS_HIDDEN_(char_type) Last() const
+  {
+    const char_type* data;
+    uint32_t dataLen = NS_StringGetData(*this, &data);
+    return data[dataLen - 1];
+  }
+
+  /**
+   * Get the length, begin writing, and optionally set the length of a
+   * string all in one operation.
+   *
+   * @param   newSize Size the string to this length. Pass UINT32_MAX
+   *                  to leave the length unchanged.
+   * @return  The new length of the string, or 0 if resizing failed.
+   */
+  NS_HIDDEN_(uint32_t) BeginWriting(char_type** aBegin,
+                                    char_type** aEnd = nullptr,
+                                    uint32_t aNewSize = UINT32_MAX);
+
+  NS_HIDDEN_(char_type*) BeginWriting(uint32_t = UINT32_MAX);
+  NS_HIDDEN_(char_type*) EndWriting();
+
+  NS_HIDDEN_(bool) SetLength(uint32_t aLen);
+
+  NS_HIDDEN_(size_type) Length() const
+  {
+    const char_type* data;
+    return NS_StringGetData(*this, &data);
+  }
+
+  NS_HIDDEN_(bool) IsEmpty() const { return Length() == 0; }
+
+  NS_HIDDEN_(void) SetIsVoid(bool aVal) { NS_StringSetIsVoid(*this, aVal); }
+  NS_HIDDEN_(bool) IsVoid() const { return NS_StringGetIsVoid(*this); }
+
+  NS_HIDDEN_(void) Assign(const self_type& aString)
+  {
+    NS_StringCopy(*this, aString);
+  }
+  NS_HIDDEN_(void) Assign(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_StringSetData(*this, aData, aLength);
+  }
+  NS_HIDDEN_(void) Assign(char_type aChar)
+  {
+    NS_StringSetData(*this, &aChar, 1);
+  }
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  NS_HIDDEN_(void) Assign(char16ptr_t aData, size_type aLength = UINT32_MAX)
+  {
+    NS_StringSetData(*this, aData, aLength);
+  }
+#endif
+
+  NS_HIDDEN_(void) AssignLiteral(const char* aStr);
+  NS_HIDDEN_(void) AssignASCII(const char* aStr)
+  {
+    AssignLiteral(aStr);
+  }
+
+  NS_HIDDEN_(self_type&) operator=(const self_type& aString)
+  {
+    Assign(aString);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator=(const char_type* aPtr)
+  {
+    Assign(aPtr);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  NS_HIDDEN_(self_type&) operator=(char16ptr_t aPtr)
+  {
+    Assign(aPtr);
+    return *this;
+  }
+#endif
+
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           const char_type* aData,
+                           size_type aLength = size_type(-1))
+  {
+    NS_StringSetDataRange(*this, aCutStart, aCutLength, aData, aLength);
+  }
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           char_type aChar)
+  {
+    Replace(aCutStart, aCutLength, &aChar, 1);
+  }
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           const self_type& aReadable)
+  {
+    const char_type* data;
+    uint32_t dataLen = NS_StringGetData(aReadable, &data);
+    NS_StringSetDataRange(*this, aCutStart, aCutLength, data, dataLen);
+  }
+  NS_HIDDEN_(void) SetCharAt(char_type aChar, index_type aPos)
+  {
+    Replace(aPos, 1, &aChar, 1);
+  }
+
+  NS_HIDDEN_(void) Append(char_type aChar)
+  {
+    Replace(size_type(-1), 0, aChar);
+  }
+  NS_HIDDEN_(void) Append(const char_type* aData,
+                          size_type aLength = size_type(-1))
+  {
+    Replace(size_type(-1), 0, aData, aLength);
+  }
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  NS_HIDDEN_(void) Append(char16ptr_t aData, size_type aLength = size_type(-1))
+  {
+    Append(static_cast<const char16_t*>(aData), aLength);
+  }
+#endif
+  NS_HIDDEN_(void) Append(const self_type& aReadable)
+  {
+    Replace(size_type(-1), 0, aReadable);
+  }
+  NS_HIDDEN_(void) AppendLiteral(const char* aASCIIStr);
+  NS_HIDDEN_(void) AppendASCII(const char* aASCIIStr)
+  {
+    AppendLiteral(aASCIIStr);
+  }
+
+  NS_HIDDEN_(self_type&) operator+=(char_type aChar)
+  {
+    Append(aChar);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator+=(const char_type* aData)
+  {
+    Append(aData);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator+=(const self_type& aReadable)
+  {
+    Append(aReadable);
+    return *this;
+  }
+
+  NS_HIDDEN_(void) Insert(char_type aChar, index_type aPos)
+  {
+    Replace(aPos, 0, aChar);
+  }
+  NS_HIDDEN_(void) Insert(const char_type* aData, index_type aPos,
+                          size_type aLength = size_type(-1))
+  {
+    Replace(aPos, 0, aData, aLength);
+  }
+  NS_HIDDEN_(void) Insert(const self_type& aReadable, index_type aPos)
+  {
+    Replace(aPos, 0, aReadable);
+  }
+
+  NS_HIDDEN_(void) Cut(index_type aCutStart, size_type aCutLength)
+  {
+    Replace(aCutStart, aCutLength, nullptr, 0);
+  }
+
+  NS_HIDDEN_(void) Truncate(size_type aNewLength = 0)
+  {
+    NS_ASSERTION(aNewLength <= Length(), "Truncate cannot make string longer");
+    SetLength(aNewLength);
+  }
+
+  /**
+   * Remove all occurences of characters in aSet from the string.
+   */
+  NS_HIDDEN_(void) StripChars(const char* aSet);
+
+  /**
+   * Strip whitespace characters from the string.
+   */
+  NS_HIDDEN_(void) StripWhitespace() { StripChars("\b\t\r\n "); }
+
+  NS_HIDDEN_(void) Trim(const char* aSet, bool aLeading = true,
+                        bool aTrailing = true);
+
+  /**
+   * Compare strings of characters. Return 0 if the characters are equal,
+   */
+  typedef int32_t (*ComparatorFunc)(const char_type* aStrA,
+                                    const char_type* aStrB,
+                                    uint32_t aLength);
+
+  static NS_HIDDEN_(int32_t) DefaultComparator(const char_type* aStrA,
+                                               const char_type* aStrB,
+                                               uint32_t aLength);
+
+  NS_HIDDEN_(int32_t) Compare(const char_type* aOther,
+                              ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(int32_t) Compare(const self_type& aOther,
+                              ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) Equals(const char_type* aOther,
+                          ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) Equals(const self_type& aOther,
+                          ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) operator<(const self_type& aOther) const
+  {
+    return Compare(aOther) < 0;
+  }
+  NS_HIDDEN_(bool) operator<(const char_type* aOther) const
+  {
+    return Compare(aOther) < 0;
+  }
+
+  NS_HIDDEN_(bool) operator<=(const self_type& aOther) const
+  {
+    return Compare(aOther) <= 0;
+  }
+  NS_HIDDEN_(bool) operator<=(const char_type* aOther) const
+  {
+    return Compare(aOther) <= 0;
+  }
+
+  NS_HIDDEN_(bool) operator==(const self_type& aOther) const
+  {
+    return Equals(aOther);
+  }
+  NS_HIDDEN_(bool) operator==(const char_type* aOther) const
+  {
+    return Equals(aOther);
+  }
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  NS_HIDDEN_(bool) operator==(char16ptr_t aOther) const
+  {
+    return Equals(aOther);
+  }
+#endif
+
+  NS_HIDDEN_(bool) operator>=(const self_type& aOther) const
+  {
+    return Compare(aOther) >= 0;
+  }
+  NS_HIDDEN_(bool) operator>=(const char_type* aOther) const
+  {
+    return Compare(aOther) >= 0;
+  }
+
+  NS_HIDDEN_(bool) operator>(const self_type& aOther) const
+  {
+    return Compare(aOther) > 0;
+  }
+  NS_HIDDEN_(bool) operator>(const char_type* aOther) const
+  {
+    return Compare(aOther) > 0;
+  }
+
+  NS_HIDDEN_(bool) operator!=(const self_type& aOther) const
+  {
+    return !Equals(aOther);
+  }
+  NS_HIDDEN_(bool) operator!=(const char_type* aOther) const
+  {
+    return !Equals(aOther);
+  }
+
+  NS_HIDDEN_(bool) EqualsLiteral(const char* aASCIIString) const;
+  NS_HIDDEN_(bool) EqualsASCII(const char* aASCIIString) const
+  {
+    return EqualsLiteral(aASCIIString);
+  }
+
+  /**
+   * Case-insensitive match this string to a lowercase ASCII string.
+   */
+  NS_HIDDEN_(bool) LowerCaseEqualsLiteral(const char* aASCIIString) const;
+
+  /**
+   * Find the first occurrence of aStr in this string.
+   *
+   * @return the offset of aStr, or -1 if not found
+   */
+  NS_HIDDEN_(int32_t) Find(const self_type& aStr,
+                           ComparatorFunc aComparator = DefaultComparator) const
+  {
+    return Find(aStr, 0, aComparator);
+  }
+
+  /**
+   * Find the first occurrence of aStr in this string, beginning at aOffset.
+   *
+   * @return the offset of aStr, or -1 if not found
+   */
+  NS_HIDDEN_(int32_t) Find(const self_type& aStr, uint32_t aOffset,
+                           ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find an ASCII string within this string.
+   *
+   * @return the offset of aStr, or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) Find(const char* aStr, bool aIgnoreCase = false) const
+  {
+    return Find(aStr, 0, aIgnoreCase);
+  }
+
+  NS_HIDDEN_(int32_t) Find(const char* aStr, uint32_t aOffset,
+                           bool aIgnoreCase = false) const;
+
+  /**
+   * Find the last occurrence of aStr in this string.
+   *
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const self_type& aStr,
+                            ComparatorFunc aComparator = DefaultComparator) const
+  {
+    return RFind(aStr, -1, aComparator);
+  }
+
+  /**
+   * Find the last occurrence of aStr in this string, beginning at aOffset.
+   *
+   * @param aOffset the offset from the beginning of the string to begin
+   *        searching. If aOffset < 0, search from end of this string.
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const self_type& aStr, int32_t aOffset,
+                            ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find the last occurrence of an ASCII string within this string.
+   *
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const char* aStr, bool aIgnoreCase = false) const
+  {
+    return RFind(aStr, -1, aIgnoreCase);
+  }
+
+  /**
+   * Find the last occurrence of an ASCII string beginning at aOffset.
+   *
+   * @param aOffset the offset from the beginning of the string to begin
+   *        searching. If aOffset < 0, search from end of this string.
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const char* aStr, int32_t aOffset,
+                            bool aIgnoreCase) const;
+
+  /**
+   * Search for the offset of the first occurrence of a character in a
+   * string.
+   *
+   * @param aOffset the offset from the beginning of the string to begin
+   *        searching
+   * @return The offset of the character from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) FindChar(char_type aChar, uint32_t aOffset = 0) const;
+
+  /**
+   * Search for the offset of the last occurrence of a character in a
+   * string.
+   *
+   * @return The offset of the character from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFindChar(char_type aChar) const;
+
+  /**
+   * Append a string representation of a number.
+   */
+  NS_HIDDEN_(void) AppendInt(int aInt, int32_t aRadix = 10);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+  /**
+   * Convert this string to an integer.
+   *
+   * @param aErrorCode pointer to contain result code.
+   * @param aRadix must be 10 or 16
+   */
+  NS_HIDDEN_(int32_t) ToInteger(nsresult* aErrorCode,
+                                uint32_t aRadix = 10) const;
+  /**
+   * Convert this string to a 64-bit integer.
+   *
+   * @param aErrorCode pointer to contain result code.
+   * @param aRadix must be 10 or 16
+   */
+  NS_HIDDEN_(int64_t) ToInteger64(nsresult* aErrorCode,
+                                  uint32_t aRadix = 10) const;
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+protected:
+  // Prevent people from allocating a nsAString directly.
+  ~nsAString() {}
+};
+
+class nsACString
+{
+public:
+  typedef char       char_type;
+  typedef nsACString self_type;
+  typedef uint32_t   size_type;
+  typedef uint32_t   index_type;
+
+  /**
+   * Returns the length, beginning, and end of a string in one operation.
+   */
+  NS_HIDDEN_(uint32_t) BeginReading(const char_type** aBegin,
+                                    const char_type** aEnd = nullptr) const;
+
+  NS_HIDDEN_(const char_type*) BeginReading() const;
+  NS_HIDDEN_(const char_type*) EndReading() const;
+
+  NS_HIDDEN_(char_type) CharAt(uint32_t aPos) const
+  {
+    NS_ASSERTION(aPos < Length(), "Out of bounds");
+    return BeginReading()[aPos];
+  }
+  NS_HIDDEN_(char_type) operator [](uint32_t aPos) const
+  {
+    return CharAt(aPos);
+  }
+  NS_HIDDEN_(char_type) First() const
+  {
+    return CharAt(0);
+  }
+  NS_HIDDEN_(char_type) Last() const
+  {
+    const char_type* data;
+    uint32_t dataLen = NS_CStringGetData(*this, &data);
+    return data[dataLen - 1];
+  }
+
+  /**
+   * Get the length, begin writing, and optionally set the length of a
+   * string all in one operation.
+   *
+   * @param   newSize Size the string to this length. Pass UINT32_MAX
+   *                  to leave the length unchanged.
+   * @return  The new length of the string, or 0 if resizing failed.
+   */
+  NS_HIDDEN_(uint32_t) BeginWriting(char_type** aBegin,
+                                    char_type** aEnd = nullptr,
+                                    uint32_t aNewSize = UINT32_MAX);
+
+  NS_HIDDEN_(char_type*) BeginWriting(uint32_t aLen = UINT32_MAX);
+  NS_HIDDEN_(char_type*) EndWriting();
+
+  NS_HIDDEN_(bool) SetLength(uint32_t aLen);
+
+  NS_HIDDEN_(size_type) Length() const
+  {
+    const char_type* data;
+    return NS_CStringGetData(*this, &data);
+  }
+
+  NS_HIDDEN_(bool) IsEmpty() const { return Length() == 0; }
+
+  NS_HIDDEN_(void) SetIsVoid(bool aVal) { NS_CStringSetIsVoid(*this, aVal); }
+  NS_HIDDEN_(bool) IsVoid() const { return NS_CStringGetIsVoid(*this); }
+
+  NS_HIDDEN_(void) Assign(const self_type& aString)
+  {
+    NS_CStringCopy(*this, aString);
+  }
+  NS_HIDDEN_(void) Assign(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_CStringSetData(*this, aData, aLength);
+  }
+  NS_HIDDEN_(void) Assign(char_type aChar)
+  {
+    NS_CStringSetData(*this, &aChar, 1);
+  }
+  NS_HIDDEN_(void) AssignLiteral(const char_type* aData)
+  {
+    Assign(aData);
+  }
+  NS_HIDDEN_(void) AssignASCII(const char_type* aData)
+  {
+    Assign(aData);
+  }
+
+  NS_HIDDEN_(self_type&) operator=(const self_type& aString)
+  {
+    Assign(aString);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator=(const char_type* aPtr)
+  {
+    Assign(aPtr);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           const char_type* aData,
+                           size_type aLength = size_type(-1))
+  {
+    NS_CStringSetDataRange(*this, aCutStart, aCutLength, aData, aLength);
+  }
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           char_type aChar)
+  {
+    Replace(aCutStart, aCutLength, &aChar, 1);
+  }
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           const self_type& aReadable)
+  {
+    const char_type* data;
+    uint32_t dataLen = NS_CStringGetData(aReadable, &data);
+    NS_CStringSetDataRange(*this, aCutStart, aCutLength, data, dataLen);
+  }
+  NS_HIDDEN_(void) SetCharAt(char_type aChar, index_type aPos)
+  {
+    Replace(aPos, 1, &aChar, 1);
+  }
+
+  NS_HIDDEN_(void) Append(char_type aChar)
+  {
+    Replace(size_type(-1), 0, aChar);
+  }
+  NS_HIDDEN_(void) Append(const char_type* aData,
+                          size_type aLength = size_type(-1))
+  {
+    Replace(size_type(-1), 0, aData, aLength);
+  }
+  NS_HIDDEN_(void) Append(const self_type& aReadable)
+  {
+    Replace(size_type(-1), 0, aReadable);
+  }
+  NS_HIDDEN_(void) AppendLiteral(const char* aASCIIStr)
+  {
+    Append(aASCIIStr);
+  }
+  NS_HIDDEN_(void) AppendASCII(const char* aASCIIStr)
+  {
+    Append(aASCIIStr);
+  }
+
+  NS_HIDDEN_(self_type&) operator+=(char_type aChar)
+  {
+    Append(aChar);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator+=(const char_type* aData)
+  {
+    Append(aData);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator+=(const self_type& aReadable)
+  {
+    Append(aReadable);
+    return *this;
+  }
+
+  NS_HIDDEN_(void) Insert(char_type aChar, index_type aPos)
+  {
+    Replace(aPos, 0, aChar);
+  }
+  NS_HIDDEN_(void) Insert(const char_type* aData, index_type aPos,
+                          size_type aLength = size_type(-1))
+  {
+    Replace(aPos, 0, aData, aLength);
+  }
+  NS_HIDDEN_(void) Insert(const self_type& aReadable, index_type aPos)
+  {
+    Replace(aPos, 0, aReadable);
+  }
+
+  NS_HIDDEN_(void) Cut(index_type aCutStart, size_type aCutLength)
+  {
+    Replace(aCutStart, aCutLength, nullptr, 0);
+  }
+
+  NS_HIDDEN_(void) Truncate(size_type aNewLength = 0)
+  {
+    NS_ASSERTION(aNewLength <= Length(), "Truncate cannot make string longer");
+    SetLength(aNewLength);
+  }
+
+  /**
+   * Remove all occurences of characters in aSet from the string.
+   */
+  NS_HIDDEN_(void) StripChars(const char* aSet);
+
+  /**
+   * Strip whitespace characters from the string.
+   */
+  NS_HIDDEN_(void) StripWhitespace() { StripChars("\b\t\r\n "); }
+
+  NS_HIDDEN_(void) Trim(const char* aSet, bool aLeading = true,
+                        bool aTrailing = true);
+
+  /**
+   * Compare strings of characters. Return 0 if the characters are equal,
+   */
+  typedef int32_t (*ComparatorFunc)(const char_type* a,
+                                    const char_type* b,
+                                    uint32_t length);
+
+  static NS_HIDDEN_(int32_t) DefaultComparator(const char_type* aStrA,
+                                               const char_type* aStrB,
+                                               uint32_t aLength);
+
+  NS_HIDDEN_(int32_t) Compare(const char_type* aOther,
+                              ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(int32_t) Compare(const self_type& aOther,
+                              ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) Equals(const char_type* aOther,
+                          ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) Equals(const self_type& aOther,
+                          ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) operator<(const self_type& aOther) const
+  {
+    return Compare(aOther) < 0;
+  }
+  NS_HIDDEN_(bool) operator<(const char_type* aOther) const
+  {
+    return Compare(aOther) < 0;
+  }
+
+  NS_HIDDEN_(bool) operator<=(const self_type& aOther) const
+  {
+    return Compare(aOther) <= 0;
+  }
+  NS_HIDDEN_(bool) operator<=(const char_type* aOther) const
+  {
+    return Compare(aOther) <= 0;
+  }
+
+  NS_HIDDEN_(bool) operator==(const self_type& aOther) const
+  {
+    return Equals(aOther);
+  }
+  NS_HIDDEN_(bool) operator==(const char_type* aOther) const
+  {
+    return Equals(aOther);
+  }
+
+  NS_HIDDEN_(bool) operator>=(const self_type& aOther) const
+  {
+    return Compare(aOther) >= 0;
+  }
+  NS_HIDDEN_(bool) operator>=(const char_type* aOther) const
+  {
+    return Compare(aOther) >= 0;
+  }
+
+  NS_HIDDEN_(bool) operator>(const self_type& aOther) const
+  {
+    return Compare(aOther) > 0;
+  }
+  NS_HIDDEN_(bool) operator>(const char_type* aOther) const
+  {
+    return Compare(aOther) > 0;
+  }
+
+  NS_HIDDEN_(bool) operator!=(const self_type& aOther) const
+  {
+    return !Equals(aOther);
+  }
+  NS_HIDDEN_(bool) operator!=(const char_type* aOther) const
+  {
+    return !Equals(aOther);
+  }
+
+  NS_HIDDEN_(bool) EqualsLiteral(const char_type* aOther) const
+  {
+    return Equals(aOther);
+  }
+  NS_HIDDEN_(bool) EqualsASCII(const char_type* aOther) const
+  {
+    return Equals(aOther);
+  }
+
+  /**
+   * Case-insensitive match this string to a lowercase ASCII string.
+   */
+  NS_HIDDEN_(bool) LowerCaseEqualsLiteral(const char* aASCIIString) const
+  {
+    return Equals(aASCIIString, CaseInsensitiveCompare);
+  }
+
+  /**
+   * Find the first occurrence of aStr in this string.
+   *
+   * @return the offset of aStr, or -1 if not found
+   */
+  NS_HIDDEN_(int32_t) Find(const self_type& aStr,
+                           ComparatorFunc aComparator = DefaultComparator) const
+  {
+    return Find(aStr, 0, aComparator);
+  }
+
+  /**
+   * Find the first occurrence of aStr in this string, beginning at aOffset.
+   *
+   * @return the offset of aStr, or -1 if not found
+   */
+  NS_HIDDEN_(int32_t) Find(const self_type& aStr, uint32_t aOffset,
+                           ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find the first occurrence of aStr in this string.
+   *
+   * @return the offset of aStr, or -1 if not found
+   */
+  NS_HIDDEN_(int32_t) Find(const char_type* aStr,
+                           ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(int32_t) Find(const char_type* aStr, uint32_t aLen,
+                           ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find the last occurrence of aStr in this string.
+   *
+   * @return The offset of the character from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const self_type& aStr,
+                            ComparatorFunc aComparator = DefaultComparator) const
+  {
+    return RFind(aStr, -1, aComparator);
+  }
+
+  /**
+   * Find the last occurrence of aStr in this string, beginning at aOffset.
+   *
+   * @param aOffset the offset from the beginning of the string to begin
+   *        searching. If aOffset < 0, search from end of this string.
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const self_type& aStr, int32_t aOffset,
+                            ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find the last occurrence of aStr in this string.
+   *
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const char_type* aStr,
+                            ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find the last occurrence of an ASCII string in this string,
+   * beginning at aOffset.
+   *
+   * @param aLen is the length of aStr
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const char_type* aStr, int32_t aLen,
+                            ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Search for the offset of the first occurrence of a character in a
+   * string.
+   *
+   * @param aOffset the offset from the beginning of the string to begin
+   *        searching
+   * @return The offset of the character from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) FindChar(char_type aChar, uint32_t aOffset = 0) const;
+
+  /**
+   * Search for the offset of the last occurrence of a character in a
+   * string.
+   *
+   * @return The offset of the character from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFindChar(char_type aChar) const;
+
+  /**
+   * Append a string representation of a number.
+   */
+  NS_HIDDEN_(void) AppendInt(int aInt, int32_t aRadix = 10);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+  /**
+   * Convert this string to an integer.
+   *
+   * @param aErrorCode pointer to contain result code.
+   * @param aRadix must be 10 or 16
+   */
+  NS_HIDDEN_(int32_t) ToInteger(nsresult* aErrorCode,
+                                uint32_t aRadix = 10) const;
+  /**
+   * Convert this string to a 64-bit integer.
+   *
+   * @param aErrorCode pointer to contain result code.
+   * @param aRadix must be 10 or 16
+   */
+  NS_HIDDEN_(int64_t) ToInteger64(nsresult* aErrorCode,
+                                  uint32_t aRadix = 10) const;
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+protected:
+  // Prevent people from allocating a nsAString directly.
+  ~nsACString() {}
+};
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Below we define nsStringContainer and nsCStringContainer.  These classes
+ * have unspecified structure.  In most cases, your code should use
+ * nsString/nsCString instead of these classes; if you prefer C-style
+ * programming, then look no further.
+ */
+
+class nsStringContainer
+  : public nsAString
+  , private nsStringContainer_base
+{
+};
+
+class nsCStringContainer
+  : public nsACString
+  , private nsStringContainer_base
+{
+};
+
+/**
+ * The following classes are C++ helper classes that make the frozen string
+ * API easier to use.
+ */
+
+/**
+ * Rename symbols to avoid conflicting with internal versions.
+ */
+#define nsString                       nsString_external
+#define nsCString                      nsCString_external
+#define nsDependentString              nsDependentString_external
+#define nsDependentCString             nsDependentCString_external
+#define NS_ConvertASCIItoUTF16         NS_ConvertASCIItoUTF16_external
+#define NS_ConvertUTF8toUTF16          NS_ConvertUTF8toUTF16_external
+#define NS_ConvertUTF16toUTF8          NS_ConvertUTF16toUTF8_external
+#define NS_LossyConvertUTF16toASCII    NS_LossyConvertUTF16toASCII_external
+#define nsGetterCopies                 nsGetterCopies_external
+#define nsCGetterCopies                nsCGetterCopies_external
+#define nsDependentSubstring           nsDependentSubstring_external
+#define nsDependentCSubstring          nsDependentCSubstring_external
+
+/**
+ * basic strings
+ */
+
+class nsString : public nsStringContainer
+{
+public:
+  typedef nsString         self_type;
+  typedef nsAString        abstract_string_type;
+
+  nsString()
+  {
+    NS_StringContainerInit(*this);
+  }
+
+  nsString(const self_type& aString)
+  {
+    NS_StringContainerInit(*this);
+    NS_StringCopy(*this, aString);
+  }
+
+  explicit nsString(const abstract_string_type& aReadable)
+  {
+    NS_StringContainerInit(*this);
+    NS_StringCopy(*this, aReadable);
+  }
+
+  explicit nsString(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_StringContainerInit2(*this, aData, aLength, 0);
+  }
+
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  explicit nsString(char16ptr_t aData, size_type aLength = UINT32_MAX)
+    : nsString(static_cast<const char16_t*>(aData), aLength)
+  {
+  }
+#endif
+
+  ~nsString()
+  {
+    NS_StringContainerFinish(*this);
+  }
+
+  char16ptr_t get() const
+  {
+    return char16ptr_t(BeginReading());
+  }
+
+  self_type& operator=(const self_type& aString)
+  {
+    Assign(aString);
+    return *this;
+  }
+  self_type& operator=(const abstract_string_type& aReadable)
+  {
+    Assign(aReadable);
+    return *this;
+  }
+  self_type& operator=(const char_type* aPtr)
+  {
+    Assign(aPtr);
+    return *this;
+  }
+  self_type& operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+
+  void Adopt(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_StringContainerFinish(*this);
+    NS_StringContainerInit2(*this, aData, aLength,
+                            NS_STRING_CONTAINER_INIT_ADOPT);
+  }
+
+protected:
+  nsString(const char_type* aData, size_type aLength, uint32_t aFlags)
+  {
+    NS_StringContainerInit2(*this, aData, aLength, aFlags);
+  }
+};
+
+class nsCString : public nsCStringContainer
+{
+public:
+  typedef nsCString        self_type;
+  typedef nsACString       abstract_string_type;
+
+  nsCString()
+  {
+    NS_CStringContainerInit(*this);
+  }
+
+  nsCString(const self_type& aString)
+  {
+    NS_CStringContainerInit(*this);
+    NS_CStringCopy(*this, aString);
+  }
+
+  explicit nsCString(const abstract_string_type& aReadable)
+  {
+    NS_CStringContainerInit(*this);
+    NS_CStringCopy(*this, aReadable);
+  }
+
+  explicit nsCString(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_CStringContainerInit(*this);
+    NS_CStringSetData(*this, aData, aLength);
+  }
+
+  ~nsCString()
+  {
+    NS_CStringContainerFinish(*this);
+  }
+
+  const char_type* get() const
+  {
+    return BeginReading();
+  }
+
+  self_type& operator=(const self_type& aString)
+  {
+    Assign(aString);
+    return *this;
+  }
+  self_type& operator=(const abstract_string_type& aReadable)
+  {
+    Assign(aReadable);
+    return *this;
+  }
+  self_type& operator=(const char_type* aPtr)
+  {
+    Assign(aPtr);
+    return *this;
+  }
+  self_type& operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+
+  void Adopt(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_CStringContainerFinish(*this);
+    NS_CStringContainerInit2(*this, aData, aLength,
+                             NS_CSTRING_CONTAINER_INIT_ADOPT);
+  }
+
+protected:
+  nsCString(const char_type* aData, size_type aLength, uint32_t aFlags)
+  {
+    NS_CStringContainerInit2(*this, aData, aLength, aFlags);
+  }
+};
+
+
+/**
+ * dependent strings
+ */
+
+class nsDependentString : public nsString
+{
+public:
+  typedef nsDependentString         self_type;
+
+  nsDependentString() {}
+
+  explicit nsDependentString(const char_type* aData,
+                             size_type aLength = UINT32_MAX)
+    : nsString(aData, aLength, NS_CSTRING_CONTAINER_INIT_DEPEND)
+  {
+  }
+
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  explicit nsDependentString(char16ptr_t aData, size_type aLength = UINT32_MAX)
+    : nsDependentString(static_cast<const char16_t*>(aData), aLength)
+  {
+  }
+#endif
+
+  void Rebind(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_StringContainerFinish(*this);
+    NS_StringContainerInit2(*this, aData, aLength,
+                            NS_STRING_CONTAINER_INIT_DEPEND);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+class nsDependentCString : public nsCString
+{
+public:
+  typedef nsDependentCString        self_type;
+
+  nsDependentCString() {}
+
+  explicit nsDependentCString(const char_type* aData,
+                              size_type aLength = UINT32_MAX)
+    : nsCString(aData, aLength, NS_CSTRING_CONTAINER_INIT_DEPEND)
+  {
+  }
+
+  void Rebind(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_CStringContainerFinish(*this);
+    NS_CStringContainerInit2(*this, aData, aLength,
+                             NS_CSTRING_CONTAINER_INIT_DEPEND);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+
+/**
+ * conversion classes
+ */
+
+inline void
+CopyUTF16toUTF8(const nsAString& aSource, nsACString& aDest)
+{
+  NS_UTF16ToCString(aSource, NS_CSTRING_ENCODING_UTF8, aDest);
+}
+
+inline void
+CopyUTF8toUTF16(const nsACString& aSource, nsAString& aDest)
+{
+  NS_CStringToUTF16(aSource, NS_CSTRING_ENCODING_UTF8, aDest);
+}
+
+inline void
+LossyCopyUTF16toASCII(const nsAString& aSource, nsACString& aDest)
+{
+  NS_UTF16ToCString(aSource, NS_CSTRING_ENCODING_ASCII, aDest);
+}
+
+inline void
+CopyASCIItoUTF16(const nsACString& aSource, nsAString& aDest)
+{
+  NS_CStringToUTF16(aSource, NS_CSTRING_ENCODING_ASCII, aDest);
+}
+
+char*
+ToNewUTF8String(const nsAString& aSource);
+
+class NS_ConvertASCIItoUTF16 : public nsString
+{
+public:
+  typedef NS_ConvertASCIItoUTF16    self_type;
+
+  explicit NS_ConvertASCIItoUTF16(const nsACString& aStr)
+  {
+    NS_CStringToUTF16(aStr, NS_CSTRING_ENCODING_ASCII, *this);
+  }
+
+  explicit NS_ConvertASCIItoUTF16(const char* aData,
+                                  uint32_t aLength = UINT32_MAX)
+  {
+    NS_CStringToUTF16(nsDependentCString(aData, aLength),
+                      NS_CSTRING_ENCODING_ASCII, *this);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+class NS_ConvertUTF8toUTF16 : public nsString
+{
+public:
+  typedef NS_ConvertUTF8toUTF16    self_type;
+
+  explicit NS_ConvertUTF8toUTF16(const nsACString& aStr)
+  {
+    NS_CStringToUTF16(aStr, NS_CSTRING_ENCODING_UTF8, *this);
+  }
+
+  explicit NS_ConvertUTF8toUTF16(const char* aData,
+                                 uint32_t aLength = UINT32_MAX)
+  {
+    NS_CStringToUTF16(nsDependentCString(aData, aLength),
+                      NS_CSTRING_ENCODING_UTF8, *this);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+class NS_ConvertUTF16toUTF8 : public nsCString
+{
+public:
+  typedef NS_ConvertUTF16toUTF8    self_type;
+
+  explicit NS_ConvertUTF16toUTF8(const nsAString& aStr)
+  {
+    NS_UTF16ToCString(aStr, NS_CSTRING_ENCODING_UTF8, *this);
+  }
+
+  explicit NS_ConvertUTF16toUTF8(const char16ptr_t aData,
+                                 uint32_t aLength = UINT32_MAX)
+  {
+    NS_UTF16ToCString(nsDependentString(aData, aLength),
+                      NS_CSTRING_ENCODING_UTF8, *this);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+class NS_LossyConvertUTF16toASCII : public nsCString
+{
+public:
+  typedef NS_LossyConvertUTF16toASCII    self_type;
+
+  explicit NS_LossyConvertUTF16toASCII(const nsAString& aStr)
+  {
+    NS_UTF16ToCString(aStr, NS_CSTRING_ENCODING_ASCII, *this);
+  }
+
+  explicit NS_LossyConvertUTF16toASCII(const char16ptr_t aData,
+                                       uint32_t aLength = UINT32_MAX)
+  {
+    NS_UTF16ToCString(nsDependentString(aData, aLength),
+                      NS_CSTRING_ENCODING_ASCII, *this);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+
+/**
+ * literal strings
+ */
+static_assert(sizeof(char16_t) == 2, "size of char16_t must be 2");
+static_assert(char16_t(-1) > char16_t(0), "char16_t must be unsigned");
+
+#define NS_MULTILINE_LITERAL_STRING(s) \
+  nsDependentString(reinterpret_cast<const nsAString::char_type*>(s), \
+                    uint32_t((sizeof(s) / 2) - 1))
+#define NS_MULTILINE_LITERAL_STRING_INIT(n, s) \
+  n(reinterpret_cast<const nsAString::char_type*>(s), \
+    uint32_t((sizeof(s) / 2) - 1))
+#define NS_NAMED_MULTILINE_LITERAL_STRING(n,s) \
+  const nsDependentString n(reinterpret_cast<const nsAString::char_type*>(s), \
+                            uint32_t((sizeof(s) / 2) - 1))
+typedef nsDependentString nsLiteralString;
+
+#define NS_LITERAL_STRING(s) \
+  static_cast<const nsString&>(NS_MULTILINE_LITERAL_STRING(u"" s))
+#define NS_LITERAL_STRING_INIT(n, s) \
+  NS_MULTILINE_LITERAL_STRING_INIT(n, (u"" s))
+#define NS_NAMED_LITERAL_STRING(n, s) \
+  NS_NAMED_MULTILINE_LITERAL_STRING(n, (u"" s))
+
+#define NS_LITERAL_CSTRING(s) \
+  static_cast<const nsDependentCString&>(nsDependentCString(s, uint32_t(sizeof(s) - 1)))
+#define NS_LITERAL_CSTRING_INIT(n, s) \
+  n(s, uint32_t(sizeof(s)-1))
+#define NS_NAMED_LITERAL_CSTRING(n, s) \
+  const nsDependentCString n(s, uint32_t(sizeof(s)-1))
+
+typedef nsDependentCString nsLiteralCString;
+
+
+/**
+ * getter_Copies support
+ *
+ *    NS_IMETHOD GetBlah(char16_t**);
+ *
+ *    void some_function()
+ *    {
+ *      nsString blah;
+ *      GetBlah(getter_Copies(blah));
+ *      // ...
+ *    }
+ */
+
+class nsGetterCopies
+{
+public:
+  typedef char16_t char_type;
+
+  explicit nsGetterCopies(nsString& aStr)
+    : mString(aStr)
+    , mData(nullptr)
+  {
+  }
+
+  ~nsGetterCopies() { mString.Adopt(mData); }
+
+  operator char_type**() { return &mData; }
+
+private:
+  nsString&  mString;
+  char_type* mData;
+};
+
+inline nsGetterCopies
+getter_Copies(nsString& aString)
+{
+  return nsGetterCopies(aString);
+}
+
+class nsCGetterCopies
+{
+public:
+  typedef char char_type;
+
+  explicit nsCGetterCopies(nsCString& aStr)
+    : mString(aStr)
+    , mData(nullptr)
+  {
+  }
+
+  ~nsCGetterCopies() { mString.Adopt(mData); }
+
+  operator char_type**() { return &mData; }
+
+private:
+  nsCString& mString;
+  char_type* mData;
+};
+
+inline nsCGetterCopies
+getter_Copies(nsCString& aString)
+{
+  return nsCGetterCopies(aString);
+}
+
+
+/**
+* substrings
+*/
+
+class nsDependentSubstring : public nsStringContainer
+{
+public:
+  typedef nsDependentSubstring self_type;
+  typedef nsAString            abstract_string_type;
+
+  ~nsDependentSubstring() { NS_StringContainerFinish(*this); }
+  nsDependentSubstring() { NS_StringContainerInit(*this); }
+
+  nsDependentSubstring(const char_type* aStart, uint32_t aLength)
+  {
+    NS_StringContainerInit2(*this, aStart, aLength,
+                            NS_STRING_CONTAINER_INIT_DEPEND |
+                            NS_STRING_CONTAINER_INIT_SUBSTRING);
+  }
+
+  nsDependentSubstring(const abstract_string_type& aStr,
+                       uint32_t aStartPos);
+  nsDependentSubstring(const abstract_string_type& aStr,
+                       uint32_t aStartPos, uint32_t aLength);
+
+  void Rebind(const char_type* aStart, uint32_t aLength)
+  {
+    NS_StringContainerFinish(*this);
+    NS_StringContainerInit2(*this, aStart, aLength,
+                            NS_STRING_CONTAINER_INIT_DEPEND |
+                            NS_STRING_CONTAINER_INIT_SUBSTRING);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+class nsDependentCSubstring : public nsCStringContainer
+{
+public:
+  typedef nsDependentCSubstring self_type;
+  typedef nsACString            abstract_string_type;
+
+  ~nsDependentCSubstring() { NS_CStringContainerFinish(*this); }
+  nsDependentCSubstring() { NS_CStringContainerInit(*this); }
+
+  nsDependentCSubstring(const char_type* aStart, uint32_t aLength)
+  {
+    NS_CStringContainerInit2(*this, aStart, aLength,
+                             NS_CSTRING_CONTAINER_INIT_DEPEND |
+                             NS_CSTRING_CONTAINER_INIT_SUBSTRING);
+  }
+
+  nsDependentCSubstring(const abstract_string_type& aStr,
+                        uint32_t aStartPos);
+  nsDependentCSubstring(const abstract_string_type& aStr,
+                        uint32_t aStartPos, uint32_t aLength);
+
+  void Rebind(const char_type* aStart, uint32_t aLength)
+  {
+    NS_CStringContainerFinish(*this);
+    NS_CStringContainerInit2(*this, aStart, aLength,
+                             NS_CSTRING_CONTAINER_INIT_DEPEND |
+                             NS_CSTRING_CONTAINER_INIT_SUBSTRING);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+
+/**
+ * Various nsDependentC?Substring constructor functions
+ */
+
+// char16_t
+inline const nsDependentSubstring
+Substring(const nsAString& aStr, uint32_t aStartPos)
+{
+  return nsDependentSubstring(aStr, aStartPos);
+}
+
+inline const nsDependentSubstring
+Substring(const nsAString& aStr, uint32_t aStartPos, uint32_t aLength)
+{
+  return nsDependentSubstring(aStr, aStartPos, aLength);
+}
+
+inline const nsDependentSubstring
+Substring(const char16_t* aStart, const char16_t* aEnd)
+{
+  MOZ_ASSERT(uint32_t(aEnd - aStart) == uintptr_t(aEnd - aStart),
+             "string too long");
+  return nsDependentSubstring(aStart, uint32_t(aEnd - aStart));
+}
+
+inline const nsDependentSubstring
+Substring(const char16_t* aStart, uint32_t aLength)
+{
+  return nsDependentSubstring(aStart, aLength);
+}
+
+inline const nsDependentSubstring
+StringHead(const nsAString& aStr, uint32_t aCount)
+{
+  return nsDependentSubstring(aStr, 0, aCount);
+}
+
+inline const nsDependentSubstring
+StringTail(const nsAString& aStr, uint32_t aCount)
+{
+  return nsDependentSubstring(aStr, aStr.Length() - aCount, aCount);
+}
+
+// char
+inline const nsDependentCSubstring
+Substring(const nsACString& aStr, uint32_t aStartPos)
+{
+  return nsDependentCSubstring(aStr, aStartPos);
+}
+
+inline const nsDependentCSubstring
+Substring(const nsACString& aStr, uint32_t aStartPos, uint32_t aLength)
+{
+  return nsDependentCSubstring(aStr, aStartPos, aLength);
+}
+
+inline const nsDependentCSubstring
+Substring(const char* aStart, const char* aEnd)
+{
+  MOZ_ASSERT(uint32_t(aEnd - aStart) == uintptr_t(aEnd - aStart),
+             "string too long");
+  return nsDependentCSubstring(aStart, uint32_t(aEnd - aStart));
+}
+
+inline const nsDependentCSubstring
+Substring(const char* aStart, uint32_t aLength)
+{
+  return nsDependentCSubstring(aStart, aLength);
+}
+
+inline const nsDependentCSubstring
+StringHead(const nsACString& aStr, uint32_t aCount)
+{
+  return nsDependentCSubstring(aStr, 0, aCount);
+}
+
+inline const nsDependentCSubstring
+StringTail(const nsACString& aStr, uint32_t aCount)
+{
+  return nsDependentCSubstring(aStr, aStr.Length() - aCount, aCount);
+}
+
+
+inline bool
+StringBeginsWith(const nsAString& aSource, const nsAString& aSubstring,
+                 nsAString::ComparatorFunc aComparator = nsAString::DefaultComparator)
+{
+  return aSubstring.Length() <= aSource.Length() &&
+    StringHead(aSource, aSubstring.Length()).Equals(aSubstring, aComparator);
+}
+
+inline bool
+StringEndsWith(const nsAString& aSource, const nsAString& aSubstring,
+               nsAString::ComparatorFunc aComparator = nsAString::DefaultComparator)
+{
+  return aSubstring.Length() <= aSource.Length() &&
+    StringTail(aSource, aSubstring.Length()).Equals(aSubstring, aComparator);
+}
+
+inline bool
+StringBeginsWith(const nsACString& aSource, const nsACString& aSubstring,
+                 nsACString::ComparatorFunc aComparator = nsACString::DefaultComparator)
+{
+  return aSubstring.Length() <= aSource.Length() &&
+    StringHead(aSource, aSubstring.Length()).Equals(aSubstring, aComparator);
+}
+
+inline bool
+StringEndsWith(const nsACString& aSource, const nsACString& aSubstring,
+               nsACString::ComparatorFunc aComparator = nsACString::DefaultComparator)
+{
+  return aSubstring.Length() <= aSource.Length() &&
+    StringTail(aSource, aSubstring.Length()).Equals(aSubstring, aComparator);
+}
+
+/**
+ * Trim whitespace from the beginning and end of a string; then compress
+ * remaining runs of whitespace characters to a single space.
+ */
+NS_HIDDEN_(void) CompressWhitespace(nsAString& aString);
+
+#define EmptyCString() nsCString()
+#define EmptyString() nsString()
+
+/**
+ * Convert an ASCII string to all upper/lowercase (a-z,A-Z only). As a bonus,
+ * returns the string length.
+ */
+NS_HIDDEN_(uint32_t) ToLowerCase(nsACString& aStr);
+
+NS_HIDDEN_(uint32_t) ToUpperCase(nsACString& aStr);
+
+NS_HIDDEN_(uint32_t) ToLowerCase(const nsACString& aSrc, nsACString& aDest);
+
+NS_HIDDEN_(uint32_t) ToUpperCase(const nsACString& aSrc, nsACString& aDest);
+
+/**
+ * The following declarations are *deprecated*, and are included here only
+ * to make porting from existing code that doesn't use the frozen string API
+ * easier. They may disappear in the future.
+ */
+
+inline char*
+ToNewCString(const nsACString& aStr)
+{
+  return NS_CStringCloneData(aStr);
+}
+
+inline char16_t*
+ToNewUnicode(const nsAString& aStr)
+{
+  return NS_StringCloneData(aStr);
+}
+
+typedef nsString PromiseFlatString;
+typedef nsCString PromiseFlatCString;
+
+typedef nsCString nsAutoCString;
+typedef nsString nsAutoString;
+
+NS_HIDDEN_(bool) ParseString(const nsACString& aAstring, char aDelimiter,
+                             nsTArray<nsCString>& aArray);
+
+#endif // nsStringAPI_h__
diff --git a/xpcom/glue/nsStringGlue.h b/xpcom/glue/nsStringGlue.h
new file mode 100644
index 0000000000..a444eb8a19
--- /dev/null
+++ b/xpcom/glue/nsStringGlue.h
@@ -0,0 +1,24 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsString.h"
+
+/**
+ * @file nsStringGlue.h
+ * This header exists solely to #include the proper internal/frozen string
+ * headers, depending on whether MOZILLA_INTERNAL_API is defined.
+ */
+
+#ifndef nsStringGlue_h__
+#define nsStringGlue_h__
+
+#ifdef MOZILLA_INTERNAL_API
+#include "nsString.h"
+#include "nsReadableUtils.h"
+#else
+#include "nsStringAPI.h"
+#endif
+
+#endif // nsStringGlue_h__
diff --git a/xpcom/glue/nsTArray-inl.h b/xpcom/glue/nsTArray-inl.h
new file mode 100644
index 0000000000..af57c9866f
--- /dev/null
+++ b/xpcom/glue/nsTArray-inl.h
@@ -0,0 +1,463 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTArray_h__
+#  error "Don't include this file directly"
+#endif
+
+template<class Alloc, class Copy>
+nsTArray_base<Alloc, Copy>::nsTArray_base()
+  : mHdr(EmptyHdr())
+{
+  MOZ_COUNT_CTOR(nsTArray_base);
+}
+
+template<class Alloc, class Copy>
+nsTArray_base<Alloc, Copy>::~nsTArray_base()
+{
+  if (mHdr != EmptyHdr() && !UsesAutoArrayBuffer()) {
+    Alloc::Free(mHdr);
+  }
+  MOZ_COUNT_DTOR(nsTArray_base);
+}
+
+template<class Alloc, class Copy>
+const nsTArrayHeader*
+nsTArray_base<Alloc, Copy>::GetAutoArrayBufferUnsafe(size_t aElemAlign) const
+{
+  // Assuming |this| points to an nsAutoArray, we want to get a pointer to
+  // mAutoBuf.  So just cast |this| to nsAutoArray* and read &mAutoBuf!
+
+  const void* autoBuf =
+    &reinterpret_cast<const AutoTArray<nsTArray<uint32_t>, 1>*>(this)->mAutoBuf;
+
+  // If we're on a 32-bit system and aElemAlign is 8, we need to adjust our
+  // pointer to take into account the extra alignment in the auto array.
+
+  static_assert(sizeof(void*) != 4 ||
+                (MOZ_ALIGNOF(mozilla::AlignedElem<8>) == 8 &&
+                 sizeof(AutoTArray<mozilla::AlignedElem<8>, 1>) ==
+                   sizeof(void*) + sizeof(nsTArrayHeader) +
+                   4 + sizeof(mozilla::AlignedElem<8>)),
+                "auto array padding wasn't what we expected");
+
+  // We don't support alignments greater than 8 bytes.
+  MOZ_ASSERT(aElemAlign <= 4 || aElemAlign == 8,
+             "unsupported alignment.");
+  if (sizeof(void*) == 4 && aElemAlign == 8) {
+    autoBuf = reinterpret_cast<const char*>(autoBuf) + 4;
+  }
+
+  return reinterpret_cast<const Header*>(autoBuf);
+}
+
+template<class Alloc, class Copy>
+bool
+nsTArray_base<Alloc, Copy>::UsesAutoArrayBuffer() const
+{
+  if (!mHdr->mIsAutoArray) {
+    return false;
+  }
+
+  // This is nuts.  If we were sane, we'd pass aElemAlign as a parameter to
+  // this function.  Unfortunately this function is called in nsTArray_base's
+  // destructor, at which point we don't know elem_type's alignment.
+  //
+  // We'll fall on our face and return true when we should say false if
+  //
+  //   * we're not using our auto buffer,
+  //   * aElemAlign == 4, and
+  //   * mHdr == GetAutoArrayBuffer(8).
+  //
+  // This could happen if |*this| lives on the heap and malloc allocated our
+  // buffer on the heap adjacent to |*this|.
+  //
+  // However, we can show that this can't happen.  If |this| is an auto array
+  // (as we ensured at the beginning of the method), GetAutoArrayBuffer(8)
+  // always points to memory owned by |*this|, because (as we assert below)
+  //
+  //   * GetAutoArrayBuffer(8) is at most 4 bytes past GetAutoArrayBuffer(4), and
+  //   * sizeof(nsTArrayHeader) > 4.
+  //
+  // Since AutoTArray always contains an nsTArrayHeader,
+  // GetAutoArrayBuffer(8) will always point inside the auto array object,
+  // even if it doesn't point at the beginning of the header.
+  //
+  // Note that this means that we can't store elements with alignment 16 in an
+  // nsTArray, because GetAutoArrayBuffer(16) could lie outside the memory
+  // owned by this AutoTArray.  We statically assert that elem_type's
+  // alignment is 8 bytes or less in AutoTArray.
+
+  static_assert(sizeof(nsTArrayHeader) > 4,
+                "see comment above");
+
+#ifdef DEBUG
+  ptrdiff_t diff = reinterpret_cast<const char*>(GetAutoArrayBuffer(8)) -
+                   reinterpret_cast<const char*>(GetAutoArrayBuffer(4));
+  MOZ_ASSERT(diff >= 0 && diff <= 4,
+             "GetAutoArrayBuffer doesn't do what we expect.");
+#endif
+
+  return mHdr == GetAutoArrayBuffer(4) || mHdr == GetAutoArrayBuffer(8);
+}
+
+// defined in nsTArray.cpp
+bool IsTwiceTheRequiredBytesRepresentableAsUint32(size_t aCapacity,
+                                                  size_t aElemSize);
+
+template<class Alloc, class Copy>
+template<typename ActualAlloc>
+typename ActualAlloc::ResultTypeProxy
+nsTArray_base<Alloc, Copy>::EnsureCapacity(size_type aCapacity,
+                                           size_type aElemSize)
+{
+  // This should be the most common case so test this first
+  if (aCapacity <= mHdr->mCapacity) {
+    return ActualAlloc::SuccessResult();
+  }
+
+  // If the requested memory allocation exceeds size_type(-1)/2, then
+  // our doubling algorithm may not be able to allocate it.
+  // Additionally, if it exceeds uint32_t(-1) then we couldn't fit in the
+  // Header::mCapacity member. Just bail out in cases like that.  We don't want
+  // to be allocating 2 GB+ arrays anyway.
+  if (!IsTwiceTheRequiredBytesRepresentableAsUint32(aCapacity, aElemSize)) {
+    ActualAlloc::SizeTooBig((size_t)aCapacity * aElemSize);
+    return ActualAlloc::FailureResult();
+  }
+
+  size_t reqSize = sizeof(Header) + aCapacity * aElemSize;
+
+  if (mHdr == EmptyHdr()) {
+    // Malloc() new data
+    Header* header = static_cast<Header*>(ActualAlloc::Malloc(reqSize));
+    if (!header) {
+      return ActualAlloc::FailureResult();
+    }
+    header->mLength = 0;
+    header->mCapacity = aCapacity;
+    header->mIsAutoArray = 0;
+    mHdr = header;
+
+    return ActualAlloc::SuccessResult();
+  }
+
+  // We increase our capacity so that the allocated buffer grows exponentially,
+  // which gives us amortized O(1) appending. Below the threshold, we use
+  // powers-of-two. Above the threshold, we grow by at least 1.125, rounding up
+  // to the nearest MiB.
+  const size_t slowGrowthThreshold = 8 * 1024 * 1024;
+
+  size_t bytesToAlloc;
+  if (reqSize >= slowGrowthThreshold) {
+    size_t currSize = sizeof(Header) + Capacity() * aElemSize;
+    size_t minNewSize = currSize + (currSize >> 3); // multiply by 1.125
+    bytesToAlloc = reqSize > minNewSize ? reqSize : minNewSize;
+
+    // Round up to the next multiple of MiB.
+    const size_t MiB = 1 << 20;
+    bytesToAlloc = MiB * ((bytesToAlloc + MiB - 1) / MiB);
+  } else {
+    // Round up to the next power of two.
+    bytesToAlloc = mozilla::RoundUpPow2(reqSize);
+  }
+
+  Header* header;
+  if (UsesAutoArrayBuffer() || !Copy::allowRealloc) {
+    // Malloc() and copy
+    header = static_cast<Header*>(ActualAlloc::Malloc(bytesToAlloc));
+    if (!header) {
+      return ActualAlloc::FailureResult();
+    }
+
+    Copy::MoveNonOverlappingRegionWithHeader(header, mHdr, Length(), aElemSize);
+
+    if (!UsesAutoArrayBuffer()) {
+      ActualAlloc::Free(mHdr);
+    }
+  } else {
+    // Realloc() existing data
+    header = static_cast<Header*>(ActualAlloc::Realloc(mHdr, bytesToAlloc));
+    if (!header) {
+      return ActualAlloc::FailureResult();
+    }
+  }
+
+  // How many elements can we fit in bytesToAlloc?
+  size_t newCapacity = (bytesToAlloc - sizeof(Header)) / aElemSize;
+  MOZ_ASSERT(newCapacity >= aCapacity, "Didn't enlarge the array enough!");
+  header->mCapacity = newCapacity;
+
+  mHdr = header;
+
+  return ActualAlloc::SuccessResult();
+}
+
+// We don't need use Alloc template parameter specified here because failure to
+// shrink the capacity will leave the array unchanged.
+template<class Alloc, class Copy>
+void
+nsTArray_base<Alloc, Copy>::ShrinkCapacity(size_type aElemSize,
+                                           size_t aElemAlign)
+{
+  if (mHdr == EmptyHdr() || UsesAutoArrayBuffer()) {
+    return;
+  }
+
+  if (mHdr->mLength >= mHdr->mCapacity) { // should never be greater than...
+    return;
+  }
+
+  size_type length = Length();
+
+  if (IsAutoArray() && GetAutoArrayBuffer(aElemAlign)->mCapacity >= length) {
+    Header* header = GetAutoArrayBuffer(aElemAlign);
+
+    // Move the data, but don't copy the header to avoid overwriting mCapacity.
+    header->mLength = length;
+    Copy::MoveNonOverlappingRegion(header + 1, mHdr + 1, length, aElemSize);
+
+    nsTArrayFallibleAllocator::Free(mHdr);
+    mHdr = header;
+    return;
+  }
+
+  if (length == 0) {
+    MOZ_ASSERT(!IsAutoArray(), "autoarray should have fit 0 elements");
+    nsTArrayFallibleAllocator::Free(mHdr);
+    mHdr = EmptyHdr();
+    return;
+  }
+
+  size_type size = sizeof(Header) + length * aElemSize;
+  void* ptr = nsTArrayFallibleAllocator::Realloc(mHdr, size);
+  if (!ptr) {
+    return;
+  }
+  mHdr = static_cast<Header*>(ptr);
+  mHdr->mCapacity = length;
+}
+
+template<class Alloc, class Copy>
+template<typename ActualAlloc>
+void
+nsTArray_base<Alloc, Copy>::ShiftData(index_type aStart,
+                                      size_type aOldLen, size_type aNewLen,
+                                      size_type aElemSize, size_t aElemAlign)
+{
+  if (aOldLen == aNewLen) {
+    return;
+  }
+
+  // Determine how many elements need to be shifted
+  size_type num = mHdr->mLength - (aStart + aOldLen);
+
+  // Compute the resulting length of the array
+  mHdr->mLength += aNewLen - aOldLen;
+  if (mHdr->mLength == 0) {
+    ShrinkCapacity(aElemSize, aElemAlign);
+  } else {
+    // Maybe nothing needs to be shifted
+    if (num == 0) {
+      return;
+    }
+    // Perform shift (change units to bytes first)
+    aStart *= aElemSize;
+    aNewLen *= aElemSize;
+    aOldLen *= aElemSize;
+    char* baseAddr = reinterpret_cast<char*>(mHdr + 1) + aStart;
+    Copy::MoveOverlappingRegion(baseAddr + aNewLen, baseAddr + aOldLen, num, aElemSize);
+  }
+}
+
+template<class Alloc, class Copy>
+template<typename ActualAlloc>
+bool
+nsTArray_base<Alloc, Copy>::InsertSlotsAt(index_type aIndex, size_type aCount,
+                                          size_type aElemSize,
+                                          size_t aElemAlign)
+{
+  MOZ_ASSERT(aIndex <= Length(), "Bogus insertion index");
+  size_type newLen = Length() + aCount;
+
+  EnsureCapacity<ActualAlloc>(newLen, aElemSize);
+
+  // Check for out of memory conditions
+  if (Capacity() < newLen) {
+    return false;
+  }
+
+  // Move the existing elements as needed.  Note that this will
+  // change our mLength, so no need to call IncrementLength.
+  ShiftData<ActualAlloc>(aIndex, 0, aCount, aElemSize, aElemAlign);
+
+  return true;
+}
+
+// nsTArray_base::IsAutoArrayRestorer is an RAII class which takes
+// |nsTArray_base &array| in its constructor.  When it's destructed, it ensures
+// that
+//
+//   * array.mIsAutoArray has the same value as it did when we started, and
+//   * if array has an auto buffer and mHdr would otherwise point to sEmptyHdr,
+//     array.mHdr points to array's auto buffer.
+
+template<class Alloc, class Copy>
+nsTArray_base<Alloc, Copy>::IsAutoArrayRestorer::IsAutoArrayRestorer(
+      nsTArray_base<Alloc, Copy>& aArray,
+      size_t aElemAlign)
+  : mArray(aArray)
+  , mElemAlign(aElemAlign)
+  , mIsAuto(aArray.IsAutoArray())
+{
+}
+
+template<class Alloc, class Copy>
+nsTArray_base<Alloc, Copy>::IsAutoArrayRestorer::~IsAutoArrayRestorer()
+{
+  // Careful: We don't want to set mIsAutoArray = 1 on sEmptyHdr.
+  if (mIsAuto && mArray.mHdr == mArray.EmptyHdr()) {
+    // Call GetAutoArrayBufferUnsafe() because GetAutoArrayBuffer() asserts
+    // that mHdr->mIsAutoArray is true, which surely isn't the case here.
+    mArray.mHdr = mArray.GetAutoArrayBufferUnsafe(mElemAlign);
+    mArray.mHdr->mLength = 0;
+  } else if (mArray.mHdr != mArray.EmptyHdr()) {
+    mArray.mHdr->mIsAutoArray = mIsAuto;
+  }
+}
+
+template<class Alloc, class Copy>
+template<typename ActualAlloc, class Allocator>
+typename ActualAlloc::ResultTypeProxy
+nsTArray_base<Alloc, Copy>::SwapArrayElements(nsTArray_base<Allocator,
+                                                            Copy>& aOther,
+                                              size_type aElemSize,
+                                              size_t aElemAlign)
+{
+
+  // EnsureNotUsingAutoArrayBuffer will set mHdr = sEmptyHdr even if we have an
+  // auto buffer.  We need to point mHdr back to our auto buffer before we
+  // return, otherwise we'll forget that we have an auto buffer at all!
+  // IsAutoArrayRestorer takes care of this for us.
+
+  IsAutoArrayRestorer ourAutoRestorer(*this, aElemAlign);
+  typename nsTArray_base<Allocator, Copy>::IsAutoArrayRestorer
+    otherAutoRestorer(aOther, aElemAlign);
+
+  // If neither array uses an auto buffer which is big enough to store the
+  // other array's elements, then ensure that both arrays use malloc'ed storage
+  // and swap their mHdr pointers.
+  if ((!UsesAutoArrayBuffer() || Capacity() < aOther.Length()) &&
+      (!aOther.UsesAutoArrayBuffer() || aOther.Capacity() < Length())) {
+
+    if (!EnsureNotUsingAutoArrayBuffer<ActualAlloc>(aElemSize) ||
+        !aOther.template EnsureNotUsingAutoArrayBuffer<ActualAlloc>(aElemSize)) {
+      return ActualAlloc::FailureResult();
+    }
+
+    Header* temp = mHdr;
+    mHdr = aOther.mHdr;
+    aOther.mHdr = temp;
+
+    return ActualAlloc::SuccessResult();
+  }
+
+  // Swap the two arrays by copying, since at least one is using an auto
+  // buffer which is large enough to hold all of the aOther's elements.  We'll
+  // copy the shorter array into temporary storage.
+  //
+  // (We could do better than this in some circumstances.  Suppose we're
+  // swapping arrays X and Y.  X has space for 2 elements in its auto buffer,
+  // but currently has length 4, so it's using malloc'ed storage.  Y has length
+  // 2.  When we swap X and Y, we don't need to use a temporary buffer; we can
+  // write Y straight into X's auto buffer, write X's malloc'ed buffer on top
+  // of Y, and then switch X to using its auto buffer.)
+
+  if (!ActualAlloc::Successful(EnsureCapacity<ActualAlloc>(aOther.Length(), aElemSize)) ||
+      !Allocator::Successful(aOther.template EnsureCapacity<Allocator>(Length(), aElemSize))) {
+    return ActualAlloc::FailureResult();
+  }
+
+  // The EnsureCapacity calls above shouldn't have caused *both* arrays to
+  // switch from their auto buffers to malloc'ed space.
+  MOZ_ASSERT(UsesAutoArrayBuffer() || aOther.UsesAutoArrayBuffer(),
+             "One of the arrays should be using its auto buffer.");
+
+  size_type smallerLength = XPCOM_MIN(Length(), aOther.Length());
+  size_type largerLength = XPCOM_MAX(Length(), aOther.Length());
+  void* smallerElements;
+  void* largerElements;
+  if (Length() <= aOther.Length()) {
+    smallerElements = Hdr() + 1;
+    largerElements = aOther.Hdr() + 1;
+  } else {
+    smallerElements = aOther.Hdr() + 1;
+    largerElements = Hdr() + 1;
+  }
+
+  // Allocate temporary storage for the smaller of the two arrays.  We want to
+  // allocate this space on the stack, if it's not too large.  Sounds like a
+  // job for AutoTArray!  (One of the two arrays we're swapping is using an
+  // auto buffer, so we're likely not allocating a lot of space here.  But one
+  // could, in theory, allocate a huge AutoTArray on the heap.)
+  AutoTArray<nsTArray_Impl<uint8_t, ActualAlloc>, 64> temp;
+  if (!ActualAlloc::Successful(temp.template EnsureCapacity<ActualAlloc>(smallerLength,
+                                                                         aElemSize))) {
+    return ActualAlloc::FailureResult();
+  }
+
+  Copy::MoveNonOverlappingRegion(temp.Elements(), smallerElements, smallerLength, aElemSize);
+  Copy::MoveNonOverlappingRegion(smallerElements, largerElements, largerLength, aElemSize);
+  Copy::MoveNonOverlappingRegion(largerElements, temp.Elements(), smallerLength, aElemSize);
+
+  // Swap the arrays' lengths.
+  MOZ_ASSERT((aOther.Length() == 0 || mHdr != EmptyHdr()) &&
+             (Length() == 0 || aOther.mHdr != EmptyHdr()),
+             "Don't set sEmptyHdr's length.");
+  size_type tempLength = Length();
+
+  // Avoid writing to EmptyHdr, since it can trigger false
+  // positives with TSan.
+  if (mHdr != EmptyHdr()) {
+    mHdr->mLength = aOther.Length();
+  }
+  if (aOther.mHdr != EmptyHdr()) {
+    aOther.mHdr->mLength = tempLength;
+  }
+
+  return ActualAlloc::SuccessResult();
+}
+
+template<class Alloc, class Copy>
+template<typename ActualAlloc>
+bool
+nsTArray_base<Alloc, Copy>::EnsureNotUsingAutoArrayBuffer(size_type aElemSize)
+{
+  if (UsesAutoArrayBuffer()) {
+
+    // If you call this on a 0-length array, we'll set that array's mHdr to
+    // sEmptyHdr, in flagrant violation of the AutoTArray invariants.  It's
+    // up to you to set it back!  (If you don't, the AutoTArray will forget
+    // that it has an auto buffer.)
+    if (Length() == 0) {
+      mHdr = EmptyHdr();
+      return true;
+    }
+
+    size_type size = sizeof(Header) + Length() * aElemSize;
+
+    Header* header = static_cast<Header*>(ActualAlloc::Malloc(size));
+    if (!header) {
+      return false;
+    }
+
+    Copy::MoveNonOverlappingRegionWithHeader(header, mHdr, Length(), aElemSize);
+    header->mCapacity = Length();
+    mHdr = header;
+  }
+
+  return true;
+}
diff --git a/xpcom/glue/nsTArray.cpp b/xpcom/glue/nsTArray.cpp
new file mode 100644
index 0000000000..fd8422ec7e
--- /dev/null
+++ b/xpcom/glue/nsTArray.cpp
@@ -0,0 +1,29 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <string.h>
+#include "nsTArray.h"
+#include "nsXPCOM.h"
+#include "nsDebug.h"
+#include "mozilla/CheckedInt.h"
+#include "mozilla/IntegerPrintfMacros.h"
+
+nsTArrayHeader nsTArrayHeader::sEmptyHdr = { 0, 0, 0 };
+
+bool
+IsTwiceTheRequiredBytesRepresentableAsUint32(size_t aCapacity, size_t aElemSize)
+{
+  using mozilla::CheckedUint32;
+  return ((CheckedUint32(aCapacity) * aElemSize) * 2).isValid();
+}
+
+MOZ_NORETURN MOZ_COLD void
+InvalidArrayIndex_CRASH(size_t aIndex, size_t aLength)
+{
+  MOZ_CRASH_UNSAFE_PRINTF(
+    "ElementAt(aIndex = %" PRIu64 ", aLength = %" PRIu64 ")",
+    static_cast<uint64_t>(aIndex), static_cast<uint64_t>(aLength));
+}
diff --git a/xpcom/glue/nsTArray.h b/xpcom/glue/nsTArray.h
new file mode 100644
index 0000000000..ca74a41f76
--- /dev/null
+++ b/xpcom/glue/nsTArray.h
@@ -0,0 +1,2371 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTArray_h__
+#define nsTArray_h__
+
+#include "nsTArrayForwardDeclare.h"
+#include "mozilla/Alignment.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/BinarySearch.h"
+#include "mozilla/fallible.h"
+#include "mozilla/Function.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Move.h"
+#include "mozilla/ReverseIterator.h"
+#include "mozilla/TypeTraits.h"
+
+#include <string.h>
+
+#include "nsCycleCollectionNoteChild.h"
+#include "nsAlgorithm.h"
+#include "nscore.h"
+#include "nsQuickSort.h"
+#include "nsDebug.h"
+#include "nsISupportsImpl.h"
+#include "nsRegionFwd.h"
+#include <initializer_list>
+#include <new>
+
+namespace JS {
+template<class T>
+class Heap;
+class ObjectPtr;
+} /* namespace JS */
+
+class nsRegion;
+namespace mozilla {
+namespace layers {
+struct TileClient;
+} // namespace layers
+} // namespace mozilla
+
+namespace mozilla {
+struct SerializedStructuredCloneBuffer;
+} // namespace mozilla
+
+namespace mozilla {
+namespace dom {
+namespace ipc {
+class StructuredCloneData;
+} // namespace ipc
+} // namespace dom
+} // namespace mozilla
+
+namespace mozilla {
+namespace dom {
+class ClonedMessageData;
+class MessagePortMessage;
+namespace indexedDB {
+struct StructuredCloneReadInfo;
+class SerializedStructuredCloneReadInfo;
+class ObjectStoreCursorResponse;
+} // namespace indexedDB
+} // namespace dom
+} // namespace mozilla
+
+class JSStructuredCloneData;
+
+//
+// nsTArray is a resizable array class, like std::vector.
+//
+// Unlike std::vector, which follows C++'s construction/destruction rules,
+// nsTArray assumes that your "T" can be memmoved()'ed safely.
+//
+// The public classes defined in this header are
+//
+//   nsTArray<T>,
+//   FallibleTArray<T>,
+//   AutoTArray<T, N>, and
+//
+// nsTArray and AutoTArray are infallible by default. To opt-in to fallible
+// behaviour, use the `mozilla::fallible` parameter and check the return value.
+//
+// If you just want to declare the nsTArray types (e.g., if you're in a header
+// file and don't need the full nsTArray definitions) consider including
+// nsTArrayForwardDeclare.h instead of nsTArray.h.
+//
+// The template parameter (i.e., T in nsTArray<T>) specifies the type of the
+// elements and has the following requirements:
+//
+//   T MUST be safely memmove()'able.
+//   T MUST define a copy-constructor.
+//   T MAY define operator< for sorting.
+//   T MAY define operator== for searching.
+//
+// (Note that the memmove requirement may be relaxed for certain types - see
+// nsTArray_CopyChooser below.)
+//
+// For methods taking a Comparator instance, the Comparator must be a class
+// defining the following methods:
+//
+//   class Comparator {
+//     public:
+//       /** @return True if the elements are equals; false otherwise. */
+//       bool Equals(const elem_type& a, const Item& b) const;
+//
+//       /** @return True if (a < b); false otherwise. */
+//       bool LessThan(const elem_type& a, const Item& b) const;
+//   };
+//
+// The Equals method is used for searching, and the LessThan method is used for
+// searching and sorting.  The |Item| type above can be arbitrary, but must
+// match the Item type passed to the sort or search function.
+//
+
+
+//
+// nsTArrayFallibleResult and nsTArrayInfallibleResult types are proxy types
+// which are used because you cannot use a templated type which is bound to
+// void as an argument to a void function.  In order to work around that, we
+// encode either a void or a boolean inside these proxy objects, and pass them
+// to the aforementioned function instead, and then use the type information to
+// decide what to do in the function.
+//
+// Note that public nsTArray methods should never return a proxy type.  Such
+// types are only meant to be used in the internal nsTArray helper methods.
+// Public methods returning non-proxy types cannot be called from other
+// nsTArray members.
+//
+struct nsTArrayFallibleResult
+{
+  // Note: allows implicit conversions from and to bool
+  MOZ_IMPLICIT nsTArrayFallibleResult(bool aResult) : mResult(aResult) {}
+
+  MOZ_IMPLICIT operator bool() { return mResult; }
+
+private:
+  bool mResult;
+};
+
+struct nsTArrayInfallibleResult
+{
+};
+
+//
+// nsTArray*Allocators must all use the same |free()|, to allow swap()'ing
+// between fallible and infallible variants.
+//
+
+struct nsTArrayFallibleAllocatorBase
+{
+  typedef bool ResultType;
+  typedef nsTArrayFallibleResult ResultTypeProxy;
+
+  static ResultType Result(ResultTypeProxy aResult) { return aResult; }
+  static bool Successful(ResultTypeProxy aResult) { return aResult; }
+  static ResultTypeProxy SuccessResult() { return true; }
+  static ResultTypeProxy FailureResult() { return false; }
+  static ResultType ConvertBoolToResultType(bool aValue) { return aValue; }
+};
+
+struct nsTArrayInfallibleAllocatorBase
+{
+  typedef void ResultType;
+  typedef nsTArrayInfallibleResult ResultTypeProxy;
+
+  static ResultType Result(ResultTypeProxy aResult) {}
+  static bool Successful(ResultTypeProxy) { return true; }
+  static ResultTypeProxy SuccessResult() { return ResultTypeProxy(); }
+
+  static ResultTypeProxy FailureResult()
+  {
+    NS_RUNTIMEABORT("Infallible nsTArray should never fail");
+    return ResultTypeProxy();
+  }
+
+  static ResultType ConvertBoolToResultType(bool aValue)
+  {
+    if (!aValue) {
+      NS_RUNTIMEABORT("infallible nsTArray should never convert false to ResultType");
+    }
+  }
+};
+
+struct nsTArrayFallibleAllocator : nsTArrayFallibleAllocatorBase
+{
+  static void* Malloc(size_t aSize) { return malloc(aSize); }
+  static void* Realloc(void* aPtr, size_t aSize)
+  {
+    return realloc(aPtr, aSize);
+  }
+
+  static void Free(void* aPtr) { free(aPtr); }
+  static void SizeTooBig(size_t) {}
+};
+
+#if defined(MOZALLOC_HAVE_XMALLOC)
+#include "mozilla/mozalloc_abort.h"
+
+struct nsTArrayInfallibleAllocator : nsTArrayInfallibleAllocatorBase
+{
+  static void* Malloc(size_t aSize) { return moz_xmalloc(aSize); }
+  static void* Realloc(void* aPtr, size_t aSize)
+  {
+    return moz_xrealloc(aPtr, aSize);
+  }
+
+  static void Free(void* aPtr) { free(aPtr); }
+  static void SizeTooBig(size_t aSize) { NS_ABORT_OOM(aSize); }
+};
+
+#else
+#include <stdlib.h>
+
+struct nsTArrayInfallibleAllocator : nsTArrayInfallibleAllocatorBase
+{
+  static void* Malloc(size_t aSize)
+  {
+    void* ptr = malloc(aSize);
+    if (MOZ_UNLIKELY(!ptr)) {
+      NS_ABORT_OOM(aSize);
+    }
+    return ptr;
+  }
+
+  static void* Realloc(void* aPtr, size_t aSize)
+  {
+    void* newptr = realloc(aPtr, aSize);
+    if (MOZ_UNLIKELY(!newptr && aSize)) {
+      NS_ABORT_OOM(aSize);
+    }
+    return newptr;
+  }
+
+  static void Free(void* aPtr) { free(aPtr); }
+  static void SizeTooBig(size_t aSize) { NS_ABORT_OOM(aSize); }
+};
+
+#endif
+
+// nsTArray_base stores elements into the space allocated beyond
+// sizeof(*this).  This is done to minimize the size of the nsTArray
+// object when it is empty.
+struct nsTArrayHeader
+{
+  static nsTArrayHeader sEmptyHdr;
+
+  uint32_t mLength;
+  uint32_t mCapacity : 31;
+  uint32_t mIsAutoArray : 1;
+};
+
+// This class provides a SafeElementAt method to nsTArray<T*> which does
+// not take a second default value parameter.
+template<class E, class Derived>
+struct nsTArray_SafeElementAtHelper
+{
+  typedef E*       elem_type;
+  typedef size_t   index_type;
+
+  // No implementation is provided for these two methods, and that is on
+  // purpose, since we don't support these functions on non-pointer type
+  // instantiations.
+  elem_type& SafeElementAt(index_type aIndex);
+  const elem_type& SafeElementAt(index_type aIndex) const;
+};
+
+template<class E, class Derived>
+struct nsTArray_SafeElementAtHelper<E*, Derived>
+{
+  typedef E*       elem_type;
+  //typedef const E* const_elem_type;   XXX: see below
+  typedef size_t   index_type;
+
+  elem_type SafeElementAt(index_type aIndex)
+  {
+    return static_cast<Derived*>(this)->SafeElementAt(aIndex, nullptr);
+  }
+
+  // XXX: Probably should return const_elem_type, but callsites must be fixed.
+  // Also, the use of const_elem_type for nsTArray<xpcGCCallback> in
+  // xpcprivate.h causes build failures on Windows because xpcGCCallback is a
+  // function pointer and MSVC doesn't like qualifying it with |const|.
+  elem_type SafeElementAt(index_type aIndex) const
+  {
+    return static_cast<const Derived*>(this)->SafeElementAt(aIndex, nullptr);
+  }
+};
+
+// E is the base type that the smart pointer is templated over; the
+// smart pointer can act as E*.
+template<class E, class Derived>
+struct nsTArray_SafeElementAtSmartPtrHelper
+{
+  typedef E*       elem_type;
+  typedef const E* const_elem_type;
+  typedef size_t   index_type;
+
+  elem_type SafeElementAt(index_type aIndex)
+  {
+    return static_cast<Derived*>(this)->SafeElementAt(aIndex, nullptr);
+  }
+
+  // XXX: Probably should return const_elem_type, but callsites must be fixed.
+  elem_type SafeElementAt(index_type aIndex) const
+  {
+    return static_cast<const Derived*>(this)->SafeElementAt(aIndex, nullptr);
+  }
+};
+
+template<class T> class nsCOMPtr;
+
+template<class E, class Derived>
+struct nsTArray_SafeElementAtHelper<nsCOMPtr<E>, Derived>
+  : public nsTArray_SafeElementAtSmartPtrHelper<E, Derived>
+{
+};
+
+template<class E, class Derived>
+struct nsTArray_SafeElementAtHelper<RefPtr<E>, Derived>
+  : public nsTArray_SafeElementAtSmartPtrHelper<E, Derived>
+{
+};
+
+namespace mozilla {
+template<class T> class OwningNonNull;
+} // namespace mozilla
+
+template<class E, class Derived>
+struct nsTArray_SafeElementAtHelper<mozilla::OwningNonNull<E>, Derived>
+{
+  typedef E*       elem_type;
+  typedef const E* const_elem_type;
+  typedef size_t   index_type;
+
+  elem_type SafeElementAt(index_type aIndex)
+  {
+    if (aIndex < static_cast<Derived*>(this)->Length()) {
+      return static_cast<Derived*>(this)->ElementAt(aIndex);
+    }
+    return nullptr;
+  }
+
+  // XXX: Probably should return const_elem_type, but callsites must be fixed.
+  elem_type SafeElementAt(index_type aIndex) const
+  {
+    if (aIndex < static_cast<const Derived*>(this)->Length()) {
+      return static_cast<const Derived*>(this)->ElementAt(aIndex);
+    }
+    return nullptr;
+  }
+};
+
+// Servo bindings.
+extern "C" void Gecko_EnsureTArrayCapacity(void* aArray,
+                                           size_t aCapacity,
+                                           size_t aElementSize);
+extern "C" void Gecko_ClearPODTArray(void* aArray,
+                                     size_t aElementSize,
+                                     size_t aElementAlign);
+
+MOZ_NORETURN MOZ_COLD void
+InvalidArrayIndex_CRASH(size_t aIndex, size_t aLength);
+
+//
+// This class serves as a base class for nsTArray.  It shouldn't be used
+// directly.  It holds common implementation code that does not depend on the
+// element type of the nsTArray.
+//
+template<class Alloc, class Copy>
+class nsTArray_base
+{
+  // Allow swapping elements with |nsTArray_base|s created using a
+  // different allocator.  This is kosher because all allocators use
+  // the same free().
+  template<class Allocator, class Copier>
+  friend class nsTArray_base;
+  friend void Gecko_EnsureTArrayCapacity(void* aArray, size_t aCapacity,
+                                         size_t aElemSize);
+  friend void Gecko_ClearPODTArray(void* aTArray, size_t aElementSize,
+                                   size_t aElementAlign);
+
+protected:
+  typedef nsTArrayHeader Header;
+
+public:
+  typedef size_t size_type;
+  typedef size_t index_type;
+
+  // @return The number of elements in the array.
+  size_type Length() const { return mHdr->mLength; }
+
+  // @return True if the array is empty or false otherwise.
+  bool IsEmpty() const { return Length() == 0; }
+
+  // @return The number of elements that can fit in the array without forcing
+  // the array to be re-allocated.  The length of an array is always less
+  // than or equal to its capacity.
+  size_type Capacity() const {  return mHdr->mCapacity; }
+
+#ifdef DEBUG
+  void* DebugGetHeader() const { return mHdr; }
+#endif
+
+protected:
+  nsTArray_base();
+
+  ~nsTArray_base();
+
+  // Resize the storage if necessary to achieve the requested capacity.
+  // @param aCapacity The requested number of array elements.
+  // @param aElemSize The size of an array element.
+  // @return False if insufficient memory is available; true otherwise.
+  template<typename ActualAlloc>
+  typename ActualAlloc::ResultTypeProxy EnsureCapacity(size_type aCapacity,
+                                                       size_type aElemSize);
+
+  // Tries to resize the storage to the minimum required amount. If this fails,
+  // the array is left as-is.
+  // @param aElemSize  The size of an array element.
+  // @param aElemAlign The alignment in bytes of an array element.
+  void ShrinkCapacity(size_type aElemSize, size_t aElemAlign);
+
+  // This method may be called to resize a "gap" in the array by shifting
+  // elements around.  It updates mLength appropriately.  If the resulting
+  // array has zero elements, then the array's memory is free'd.
+  // @param aStart     The starting index of the gap.
+  // @param aOldLen    The current length of the gap.
+  // @param aNewLen    The desired length of the gap.
+  // @param aElemSize  The size of an array element.
+  // @param aElemAlign The alignment in bytes of an array element.
+  template<typename ActualAlloc>
+  void ShiftData(index_type aStart, size_type aOldLen, size_type aNewLen,
+                 size_type aElemSize, size_t aElemAlign);
+
+  // This method increments the length member of the array's header.
+  // Note that mHdr may actually be sEmptyHdr in the case where a
+  // zero-length array is inserted into our array. But then aNum should
+  // always be 0.
+  void IncrementLength(size_t aNum)
+  {
+    if (mHdr == EmptyHdr()) {
+      if (MOZ_UNLIKELY(aNum != 0)) {
+        // Writing a non-zero length to the empty header would be extremely bad.
+        MOZ_CRASH();
+      }
+    } else {
+      mHdr->mLength += aNum;
+    }
+  }
+
+  // This method inserts blank slots into the array.
+  // @param aIndex the place to insert the new elements. This must be no
+  //               greater than the current length of the array.
+  // @param aCount the number of slots to insert
+  // @param aElementSize the size of an array element.
+  // @param aElemAlign the alignment in bytes of an array element.
+  template<typename ActualAlloc>
+  bool InsertSlotsAt(index_type aIndex, size_type aCount,
+                     size_type aElementSize, size_t aElemAlign);
+
+  template<typename ActualAlloc, class Allocator>
+  typename ActualAlloc::ResultTypeProxy
+  SwapArrayElements(nsTArray_base<Allocator, Copy>& aOther,
+                    size_type aElemSize,
+                    size_t aElemAlign);
+
+  // This is an RAII class used in SwapArrayElements.
+  class IsAutoArrayRestorer
+  {
+  public:
+    IsAutoArrayRestorer(nsTArray_base<Alloc, Copy>& aArray, size_t aElemAlign);
+    ~IsAutoArrayRestorer();
+
+  private:
+    nsTArray_base<Alloc, Copy>& mArray;
+    size_t mElemAlign;
+    bool mIsAuto;
+  };
+
+  // Helper function for SwapArrayElements. Ensures that if the array
+  // is an AutoTArray that it doesn't use the built-in buffer.
+  template<typename ActualAlloc>
+  bool EnsureNotUsingAutoArrayBuffer(size_type aElemSize);
+
+  // Returns true if this nsTArray is an AutoTArray with a built-in buffer.
+  bool IsAutoArray() const { return mHdr->mIsAutoArray; }
+
+  // Returns a Header for the built-in buffer of this AutoTArray.
+  Header* GetAutoArrayBuffer(size_t aElemAlign)
+  {
+    MOZ_ASSERT(IsAutoArray(), "Should be an auto array to call this");
+    return GetAutoArrayBufferUnsafe(aElemAlign);
+  }
+  const Header* GetAutoArrayBuffer(size_t aElemAlign) const
+  {
+    MOZ_ASSERT(IsAutoArray(), "Should be an auto array to call this");
+    return GetAutoArrayBufferUnsafe(aElemAlign);
+  }
+
+  // Returns a Header for the built-in buffer of this AutoTArray, but doesn't
+  // assert that we are an AutoTArray.
+  Header* GetAutoArrayBufferUnsafe(size_t aElemAlign)
+  {
+    return const_cast<Header*>(static_cast<const nsTArray_base<Alloc, Copy>*>(
+      this)->GetAutoArrayBufferUnsafe(aElemAlign));
+  }
+  const Header* GetAutoArrayBufferUnsafe(size_t aElemAlign) const;
+
+  // Returns true if this is an AutoTArray and it currently uses the
+  // built-in buffer to store its elements.
+  bool UsesAutoArrayBuffer() const;
+
+  // The array's elements (prefixed with a Header).  This pointer is never
+  // null.  If the array is empty, then this will point to sEmptyHdr.
+  Header* mHdr;
+
+  Header* Hdr() const { return mHdr; }
+  Header** PtrToHdr() { return &mHdr; }
+  static Header* EmptyHdr() { return &Header::sEmptyHdr; }
+};
+
+//
+// This class defines convenience functions for element specific operations.
+// Specialize this template if necessary.
+//
+template<class E>
+class nsTArrayElementTraits
+{
+public:
+  // Invoke the default constructor in place.
+  static inline void Construct(E* aE)
+  {
+    // Do NOT call "E()"! That triggers C++ "default initialization"
+    // which zeroes out POD ("plain old data") types such as regular
+    // ints.  We don't want that because it can be a performance issue
+    // and people don't expect it; nsTArray should work like a regular
+    // C/C++ array in this respect.
+    new (static_cast<void*>(aE)) E;
+  }
+  // Invoke the copy-constructor in place.
+  template<class A>
+  static inline void Construct(E* aE, A&& aArg)
+  {
+    typedef typename mozilla::RemoveCV<E>::Type E_NoCV;
+    typedef typename mozilla::RemoveCV<A>::Type A_NoCV;
+    static_assert(!mozilla::IsSame<E_NoCV*, A_NoCV>::value,
+                  "For safety, we disallow constructing nsTArray<E> elements "
+                  "from E* pointers. See bug 960591.");
+    new (static_cast<void*>(aE)) E(mozilla::Forward<A>(aArg));
+  }
+  // Invoke the destructor in place.
+  static inline void Destruct(E* aE) { aE->~E(); }
+};
+
+// The default comparator used by nsTArray
+template<class A, class B>
+class nsDefaultComparator
+{
+public:
+  bool Equals(const A& aA, const B& aB) const { return aA == aB; }
+  bool LessThan(const A& aA, const B& aB) const { return aA < aB; }
+};
+
+template<bool IsPod, bool IsSameType>
+struct AssignRangeAlgorithm
+{
+  template<class Item, class ElemType, class IndexType, class SizeType>
+  static void implementation(ElemType* aElements, IndexType aStart,
+                             SizeType aCount, const Item* aValues)
+  {
+    ElemType* iter = aElements + aStart;
+    ElemType* end = iter + aCount;
+    for (; iter != end; ++iter, ++aValues) {
+      nsTArrayElementTraits<ElemType>::Construct(iter, *aValues);
+    }
+  }
+};
+
+template<>
+struct AssignRangeAlgorithm<true, true>
+{
+  template<class Item, class ElemType, class IndexType, class SizeType>
+  static void implementation(ElemType* aElements, IndexType aStart,
+                             SizeType aCount, const Item* aValues)
+  {
+    memcpy(aElements + aStart, aValues, aCount * sizeof(ElemType));
+  }
+};
+
+//
+// Normally elements are copied with memcpy and memmove, but for some element
+// types that is problematic.  The nsTArray_CopyChooser template class can be
+// specialized to ensure that copying calls constructors and destructors
+// instead, as is done below for JS::Heap<E> elements.
+//
+
+//
+// A class that defines how to copy elements using memcpy/memmove.
+//
+struct nsTArray_CopyWithMemutils
+{
+  const static bool allowRealloc = true;
+
+  static void MoveNonOverlappingRegionWithHeader(void* aDest, const void* aSrc,
+                                                 size_t aCount, size_t aElemSize)
+  {
+    memcpy(aDest, aSrc, sizeof(nsTArrayHeader) + aCount * aElemSize);
+  }
+
+  static void MoveOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
+                                    size_t aElemSize)
+  {
+    memmove(aDest, aSrc, aCount * aElemSize);
+  }
+
+  static void MoveNonOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
+                                       size_t aElemSize)
+  {
+    memcpy(aDest, aSrc, aCount * aElemSize);
+  }
+};
+
+//
+// A template class that defines how to copy elements calling their constructors
+// and destructors appropriately.
+//
+template<class ElemType>
+struct nsTArray_CopyWithConstructors
+{
+  typedef nsTArrayElementTraits<ElemType> traits;
+
+  const static bool allowRealloc = false;
+
+  static void MoveNonOverlappingRegionWithHeader(void* aDest, void* aSrc, size_t aCount,
+                                                 size_t aElemSize)
+  {
+    nsTArrayHeader* destHeader = static_cast<nsTArrayHeader*>(aDest);
+    nsTArrayHeader* srcHeader = static_cast<nsTArrayHeader*>(aSrc);
+    *destHeader = *srcHeader;
+    MoveNonOverlappingRegion(static_cast<uint8_t*>(aDest) + sizeof(nsTArrayHeader),
+                             static_cast<uint8_t*>(aSrc) + sizeof(nsTArrayHeader),
+                             aCount, aElemSize);
+  }
+
+  // These functions are defined by analogy with memmove and memcpy.
+  // What they actually do is slightly different: MoveOverlappingRegion
+  // checks to see which direction the movement needs to take place,
+  // whether from back-to-front of the range to be moved or from
+  // front-to-back.  MoveNonOverlappingRegion assumes that moving
+  // front-to-back is always valid.  So they're really more like
+  // std::move{_backward,} in that respect.  We keep these names because
+  // we think they read slightly better, and MoveNonOverlappingRegion is
+  // only ever called on overlapping regions from MoveOverlappingRegion.
+  static void MoveOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
+                                    size_t aElemSize)
+  {
+    ElemType* destElem = static_cast<ElemType*>(aDest);
+    ElemType* srcElem = static_cast<ElemType*>(aSrc);
+    ElemType* destElemEnd = destElem + aCount;
+    ElemType* srcElemEnd = srcElem + aCount;
+    if (destElem == srcElem) {
+      return;  // In practice, we don't do this.
+    }
+
+    // Figure out whether to copy back-to-front or front-to-back.
+    if (srcElemEnd > destElem && srcElemEnd < destElemEnd) {
+      while (destElemEnd != destElem) {
+        --destElemEnd;
+        --srcElemEnd;
+        traits::Construct(destElemEnd, mozilla::Move(*srcElemEnd));
+        traits::Destruct(srcElemEnd);
+      }
+    } else {
+      MoveNonOverlappingRegion(aDest, aSrc, aCount, aElemSize);
+    }
+  }
+
+  static void MoveNonOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
+                                       size_t aElemSize)
+  {
+    ElemType* destElem = static_cast<ElemType*>(aDest);
+    ElemType* srcElem = static_cast<ElemType*>(aSrc);
+    ElemType* destElemEnd = destElem + aCount;
+#ifdef DEBUG
+    ElemType* srcElemEnd = srcElem + aCount;
+    MOZ_ASSERT(srcElemEnd <= destElem || srcElemEnd > destElemEnd);
+#endif
+    while (destElem != destElemEnd) {
+      traits::Construct(destElem, mozilla::Move(*srcElem));
+      traits::Destruct(srcElem);
+      ++destElem;
+      ++srcElem;
+    }
+  }
+};
+
+//
+// The default behaviour is to use memcpy/memmove for everything.
+//
+template<class E>
+struct MOZ_NEEDS_MEMMOVABLE_TYPE nsTArray_CopyChooser
+{
+  using Type = nsTArray_CopyWithMemutils;
+};
+
+//
+// Some classes require constructors/destructors to be called, so they are
+// specialized here.
+//
+#define DECLARE_USE_COPY_CONSTRUCTORS(T)                \
+  template<>                                            \
+  struct nsTArray_CopyChooser<T>                        \
+  {                                                     \
+    using Type = nsTArray_CopyWithConstructors<T>;      \
+  };
+
+#define DECLARE_USE_COPY_CONSTRUCTORS_FOR_TEMPLATE(T)   \
+  template<typename S>                                  \
+  struct nsTArray_CopyChooser<T<S>>                     \
+  {                                                     \
+    using Type = nsTArray_CopyWithConstructors<T<S>>;   \
+  };
+
+DECLARE_USE_COPY_CONSTRUCTORS_FOR_TEMPLATE(JS::Heap)
+
+DECLARE_USE_COPY_CONSTRUCTORS(nsRegion)
+DECLARE_USE_COPY_CONSTRUCTORS(nsIntRegion)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::layers::TileClient)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::SerializedStructuredCloneBuffer)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::ipc::StructuredCloneData)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::ClonedMessageData)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::indexedDB::StructuredCloneReadInfo);
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::indexedDB::ObjectStoreCursorResponse)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::indexedDB::SerializedStructuredCloneReadInfo);
+DECLARE_USE_COPY_CONSTRUCTORS(JSStructuredCloneData)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::MessagePortMessage)
+DECLARE_USE_COPY_CONSTRUCTORS(JS::ObjectPtr)
+
+
+//
+// Base class for nsTArray_Impl that is templated on element type and derived
+// nsTArray_Impl class, to allow extra conversions to be added for specific
+// types.
+//
+template<class E, class Derived>
+struct nsTArray_TypedBase : public nsTArray_SafeElementAtHelper<E, Derived>
+{
+};
+
+//
+// Specialization of nsTArray_TypedBase for arrays containing JS::Heap<E>
+// elements.
+//
+// These conversions are safe because JS::Heap<E> and E share the same
+// representation, and since the result of the conversions are const references
+// we won't miss any barriers.
+//
+// The static_cast is necessary to obtain the correct address for the derived
+// class since we are a base class used in multiple inheritance.
+//
+template<class E, class Derived>
+struct nsTArray_TypedBase<JS::Heap<E>, Derived>
+  : public nsTArray_SafeElementAtHelper<JS::Heap<E>, Derived>
+{
+  operator const nsTArray<E>&()
+  {
+    static_assert(sizeof(E) == sizeof(JS::Heap<E>),
+                  "JS::Heap<E> must be binary compatible with E.");
+    Derived* self = static_cast<Derived*>(this);
+    return *reinterpret_cast<nsTArray<E> *>(self);
+  }
+
+  operator const FallibleTArray<E>&()
+  {
+    Derived* self = static_cast<Derived*>(this);
+    return *reinterpret_cast<FallibleTArray<E> *>(self);
+  }
+};
+
+namespace detail {
+
+template<class Item, class Comparator>
+struct ItemComparatorEq
+{
+  const Item& mItem;
+  const Comparator& mComp;
+  ItemComparatorEq(const Item& aItem, const Comparator& aComp)
+    : mItem(aItem)
+    , mComp(aComp)
+  {}
+  template<class T>
+  int operator()(const T& aElement) const {
+    if (mComp.Equals(aElement, mItem)) {
+      return 0;
+    }
+
+    return mComp.LessThan(aElement, mItem) ? 1 : -1;
+  }
+};
+
+template<class Item, class Comparator>
+struct ItemComparatorFirstElementGT
+{
+  const Item& mItem;
+  const Comparator& mComp;
+  ItemComparatorFirstElementGT(const Item& aItem, const Comparator& aComp)
+    : mItem(aItem)
+    , mComp(aComp)
+  {}
+  template<class T>
+  int operator()(const T& aElement) const {
+    if (mComp.LessThan(aElement, mItem) ||
+        mComp.Equals(aElement, mItem)) {
+      return 1;
+    } else {
+      return -1;
+    }
+  }
+};
+
+} // namespace detail
+
+//
+// nsTArray_Impl contains most of the guts supporting nsTArray, FallibleTArray,
+// AutoTArray.
+//
+// The only situation in which you might need to use nsTArray_Impl in your code
+// is if you're writing code which mutates a TArray which may or may not be
+// infallible.
+//
+// Code which merely reads from a TArray which may or may not be infallible can
+// simply cast the TArray to |const nsTArray&|; both fallible and infallible
+// TArrays can be cast to |const nsTArray&|.
+//
+template<class E, class Alloc>
+class nsTArray_Impl
+  : public nsTArray_base<Alloc, typename nsTArray_CopyChooser<E>::Type>
+  , public nsTArray_TypedBase<E, nsTArray_Impl<E, Alloc>>
+{
+private:
+  typedef nsTArrayFallibleAllocator FallibleAlloc;
+  typedef nsTArrayInfallibleAllocator InfallibleAlloc;
+
+public:
+  typedef typename nsTArray_CopyChooser<E>::Type     copy_type;
+  typedef nsTArray_base<Alloc, copy_type>            base_type;
+  typedef typename base_type::size_type              size_type;
+  typedef typename base_type::index_type             index_type;
+  typedef E                                          elem_type;
+  typedef nsTArray_Impl<E, Alloc>                    self_type;
+  typedef nsTArrayElementTraits<E>                   elem_traits;
+  typedef nsTArray_SafeElementAtHelper<E, self_type> safeelementat_helper_type;
+  typedef elem_type*                                 iterator;
+  typedef const elem_type*                           const_iterator;
+  typedef mozilla::ReverseIterator<elem_type*>       reverse_iterator;
+  typedef mozilla::ReverseIterator<const elem_type*> const_reverse_iterator;
+
+  using safeelementat_helper_type::SafeElementAt;
+  using base_type::EmptyHdr;
+
+  // A special value that is used to indicate an invalid or unknown index
+  // into the array.
+  static const index_type NoIndex = index_type(-1);
+
+  using base_type::Length;
+
+  //
+  // Finalization method
+  //
+
+  ~nsTArray_Impl() { Clear(); }
+
+  //
+  // Initialization methods
+  //
+
+  nsTArray_Impl() {}
+
+  // Initialize this array and pre-allocate some number of elements.
+  explicit nsTArray_Impl(size_type aCapacity) { SetCapacity(aCapacity); }
+
+  // Initialize this array with an r-value.
+  // Allow different types of allocators, since the allocator doesn't matter.
+  template<typename Allocator>
+  explicit nsTArray_Impl(nsTArray_Impl<E, Allocator>&& aOther)
+  {
+    SwapElements(aOther);
+  }
+
+  // The array's copy-constructor performs a 'deep' copy of the given array.
+  // @param aOther The array object to copy.
+  //
+  // It's very important that we declare this method as taking |const
+  // self_type&| as opposed to taking |const nsTArray_Impl<E, OtherAlloc>| for
+  // an arbitrary OtherAlloc.
+  //
+  // If we don't declare a constructor taking |const self_type&|, C++ generates
+  // a copy-constructor for this class which merely copies the object's
+  // members, which is obviously wrong.
+  //
+  // You can pass an nsTArray_Impl<E, OtherAlloc> to this method because
+  // nsTArray_Impl<E, X> can be cast to const nsTArray_Impl<E, Y>&.  So the
+  // effect on the API is the same as if we'd declared this method as taking
+  // |const nsTArray_Impl<E, OtherAlloc>&|.
+  explicit nsTArray_Impl(const self_type& aOther) { AppendElements(aOther); }
+
+  explicit nsTArray_Impl(std::initializer_list<E> aIL) { AppendElements(aIL.begin(), aIL.size()); }
+  // Allow converting to a const array with a different kind of allocator,
+  // Since the allocator doesn't matter for const arrays
+  template<typename Allocator>
+  operator const nsTArray_Impl<E, Allocator>&() const
+  {
+    return *reinterpret_cast<const nsTArray_Impl<E, Allocator>*>(this);
+  }
+  // And we have to do this for our subclasses too
+  operator const nsTArray<E>&() const
+  {
+    return *reinterpret_cast<const InfallibleTArray<E>*>(this);
+  }
+  operator const FallibleTArray<E>&() const
+  {
+    return *reinterpret_cast<const FallibleTArray<E>*>(this);
+  }
+
+  // The array's assignment operator performs a 'deep' copy of the given
+  // array.  It is optimized to reuse existing storage if possible.
+  // @param aOther The array object to copy.
+  self_type& operator=(const self_type& aOther)
+  {
+    if (this != &aOther) {
+      ReplaceElementsAt(0, Length(), aOther.Elements(), aOther.Length());
+    }
+    return *this;
+  }
+
+  // The array's move assignment operator steals the underlying data from
+  // the other array.
+  // @param other  The array object to move from.
+  self_type& operator=(self_type&& aOther)
+  {
+    if (this != &aOther) {
+      Clear();
+      SwapElements(aOther);
+    }
+    return *this;
+  }
+
+  // Return true if this array has the same length and the same
+  // elements as |aOther|.
+  template<typename Allocator>
+  bool operator==(const nsTArray_Impl<E, Allocator>& aOther) const
+  {
+    size_type len = Length();
+    if (len != aOther.Length()) {
+      return false;
+    }
+
+    // XXX std::equal would be as fast or faster here
+    for (index_type i = 0; i < len; ++i) {
+      if (!(operator[](i) == aOther[i])) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  // Return true if this array does not have the same length and the same
+  // elements as |aOther|.
+  bool operator!=(const self_type& aOther) const { return !operator==(aOther); }
+
+  template<typename Allocator>
+  self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther)
+  {
+    ReplaceElementsAt(0, Length(), aOther.Elements(), aOther.Length());
+    return *this;
+  }
+
+  template<typename Allocator>
+  self_type& operator=(nsTArray_Impl<E, Allocator>&& aOther)
+  {
+    Clear();
+    SwapElements(aOther);
+    return *this;
+  }
+
+  // @return The amount of memory used by this nsTArray_Impl, excluding
+  // sizeof(*this). If you want to measure anything hanging off the array, you
+  // must iterate over the elements and measure them individually; hence the
+  // "Shallow" prefix.
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    if (this->UsesAutoArrayBuffer() || Hdr() == EmptyHdr()) {
+      return 0;
+    }
+    return aMallocSizeOf(this->Hdr());
+  }
+
+  // @return The amount of memory used by this nsTArray_Impl, including
+  // sizeof(*this). If you want to measure anything hanging off the array, you
+  // must iterate over the elements and measure them individually; hence the
+  // "Shallow" prefix.
+  size_t ShallowSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  //
+  // Accessor methods
+  //
+
+  // This method provides direct access to the array elements.
+  // @return A pointer to the first element of the array.  If the array is
+  // empty, then this pointer must not be dereferenced.
+  elem_type* Elements() { return reinterpret_cast<elem_type*>(Hdr() + 1); }
+
+  // This method provides direct, readonly access to the array elements.
+  // @return A pointer to the first element of the array.  If the array is
+  // empty, then this pointer must not be dereferenced.
+  const elem_type* Elements() const
+  {
+    return reinterpret_cast<const elem_type*>(Hdr() + 1);
+  }
+
+  // This method provides direct access to an element of the array. The given
+  // index must be within the array bounds.
+  // @param aIndex The index of an element in the array.
+  // @return A reference to the i'th element of the array.
+  elem_type& ElementAt(index_type aIndex)
+  {
+    if (MOZ_UNLIKELY(aIndex >= Length())) {
+      InvalidArrayIndex_CRASH(aIndex, Length());
+    }
+    return Elements()[aIndex];
+  }
+
+  // This method provides direct, readonly access to an element of the array
+  // The given index must be within the array bounds.
+  // @param aIndex The index of an element in the array.
+  // @return A const reference to the i'th element of the array.
+  const elem_type& ElementAt(index_type aIndex) const
+  {
+    if (MOZ_UNLIKELY(aIndex >= Length())) {
+      InvalidArrayIndex_CRASH(aIndex, Length());
+    }
+    return Elements()[aIndex];
+  }
+
+  // This method provides direct access to an element of the array in a bounds
+  // safe manner. If the requested index is out of bounds the provided default
+  // value is returned.
+  // @param aIndex The index of an element in the array.
+  // @param aDef   The value to return if the index is out of bounds.
+  elem_type& SafeElementAt(index_type aIndex, elem_type& aDef)
+  {
+    return aIndex < Length() ? Elements()[aIndex] : aDef;
+  }
+
+  // This method provides direct access to an element of the array in a bounds
+  // safe manner. If the requested index is out of bounds the provided default
+  // value is returned.
+  // @param aIndex The index of an element in the array.
+  // @param aDef   The value to return if the index is out of bounds.
+  const elem_type& SafeElementAt(index_type aIndex, const elem_type& aDef) const
+  {
+    return aIndex < Length() ? Elements()[aIndex] : aDef;
+  }
+
+  // Shorthand for ElementAt(aIndex)
+  elem_type& operator[](index_type aIndex) { return ElementAt(aIndex); }
+
+  // Shorthand for ElementAt(aIndex)
+  const elem_type& operator[](index_type aIndex) const { return ElementAt(aIndex); }
+
+  // Shorthand for ElementAt(length - 1)
+  elem_type& LastElement() { return ElementAt(Length() - 1); }
+
+  // Shorthand for ElementAt(length - 1)
+  const elem_type& LastElement() const { return ElementAt(Length() - 1); }
+
+  // Shorthand for SafeElementAt(length - 1, def)
+  elem_type& SafeLastElement(elem_type& aDef)
+  {
+    return SafeElementAt(Length() - 1, aDef);
+  }
+
+  // Shorthand for SafeElementAt(length - 1, def)
+  const elem_type& SafeLastElement(const elem_type& aDef) const
+  {
+    return SafeElementAt(Length() - 1, aDef);
+  }
+
+  // Methods for range-based for loops.
+  iterator begin() { return Elements(); }
+  const_iterator begin() const { return Elements(); }
+  const_iterator cbegin() const { return begin(); }
+  iterator end() { return Elements() + Length(); }
+  const_iterator end() const { return Elements() + Length(); }
+  const_iterator cend() const { return end(); }
+
+  // Methods for reverse iterating.
+  reverse_iterator rbegin() { return reverse_iterator(end()); }
+  const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); }
+  const_reverse_iterator crbegin() const { return rbegin(); }
+  reverse_iterator rend() { return reverse_iterator(begin()); }
+  const_reverse_iterator rend() const { return const_reverse_iterator(begin()); }
+  const_reverse_iterator crend() const { return rend(); }
+
+  //
+  // Search methods
+  //
+
+  // This method searches for the first element in this array that is equal
+  // to the given element.
+  // @param aItem  The item to search for.
+  // @param aComp  The Comparator used to determine element equality.
+  // @return       true if the element was found.
+  template<class Item, class Comparator>
+  bool Contains(const Item& aItem, const Comparator& aComp) const
+  {
+    return IndexOf(aItem, 0, aComp) != NoIndex;
+  }
+
+  // This method searches for the first element in this array that is equal
+  // to the given element.  This method assumes that 'operator==' is defined
+  // for elem_type.
+  // @param aItem  The item to search for.
+  // @return       true if the element was found.
+  template<class Item>
+  bool Contains(const Item& aItem) const
+  {
+    return IndexOf(aItem) != NoIndex;
+  }
+
+  // This method searches for the offset of the first element in this
+  // array that is equal to the given element.
+  // @param aItem  The item to search for.
+  // @param aStart The index to start from.
+  // @param aComp  The Comparator used to determine element equality.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item, class Comparator>
+  index_type IndexOf(const Item& aItem, index_type aStart,
+                     const Comparator& aComp) const
+  {
+    const elem_type* iter = Elements() + aStart;
+    const elem_type* iend = Elements() + Length();
+    for (; iter != iend; ++iter) {
+      if (aComp.Equals(*iter, aItem)) {
+        return index_type(iter - Elements());
+      }
+    }
+    return NoIndex;
+  }
+
+  // This method searches for the offset of the first element in this
+  // array that is equal to the given element.  This method assumes
+  // that 'operator==' is defined for elem_type.
+  // @param aItem  The item to search for.
+  // @param aStart The index to start from.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item>
+  index_type IndexOf(const Item& aItem, index_type aStart = 0) const
+  {
+    return IndexOf(aItem, aStart, nsDefaultComparator<elem_type, Item>());
+  }
+
+  // This method searches for the offset of the last element in this
+  // array that is equal to the given element.
+  // @param aItem  The item to search for.
+  // @param aStart The index to start from.  If greater than or equal to the
+  //               length of the array, then the entire array is searched.
+  // @param aComp  The Comparator used to determine element equality.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item, class Comparator>
+  index_type LastIndexOf(const Item& aItem, index_type aStart,
+                         const Comparator& aComp) const
+  {
+    size_type endOffset = aStart >= Length() ? Length() : aStart + 1;
+    const elem_type* iend = Elements() - 1;
+    const elem_type* iter = iend + endOffset;
+    for (; iter != iend; --iter) {
+      if (aComp.Equals(*iter, aItem)) {
+        return index_type(iter - Elements());
+      }
+    }
+    return NoIndex;
+  }
+
+  // This method searches for the offset of the last element in this
+  // array that is equal to the given element.  This method assumes
+  // that 'operator==' is defined for elem_type.
+  // @param aItem  The item to search for.
+  // @param aStart The index to start from.  If greater than or equal to the
+  //               length of the array, then the entire array is searched.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item>
+  index_type LastIndexOf(const Item& aItem,
+                         index_type aStart = NoIndex) const
+  {
+    return LastIndexOf(aItem, aStart, nsDefaultComparator<elem_type, Item>());
+  }
+
+  // This method searches for the offset for the element in this array
+  // that is equal to the given element. The array is assumed to be sorted.
+  // If there is more than one equivalent element, there is no guarantee
+  // on which one will be returned.
+  // @param aItem  The item to search for.
+  // @param aComp  The Comparator used.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item, class Comparator>
+  index_type BinaryIndexOf(const Item& aItem, const Comparator& aComp) const
+  {
+    using mozilla::BinarySearchIf;
+    typedef ::detail::ItemComparatorEq<Item, Comparator> Cmp;
+
+    size_t index;
+    bool found = BinarySearchIf(*this, 0, Length(), Cmp(aItem, aComp), &index);
+    return found ? index : NoIndex;
+  }
+
+  // This method searches for the offset for the element in this array
+  // that is equal to the given element. The array is assumed to be sorted.
+  // This method assumes that 'operator==' and 'operator<' are defined.
+  // @param aItem  The item to search for.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item>
+  index_type BinaryIndexOf(const Item& aItem) const
+  {
+    return BinaryIndexOf(aItem, nsDefaultComparator<elem_type, Item>());
+  }
+
+  //
+  // Mutation methods
+  //
+
+  template<class Allocator, typename ActualAlloc = Alloc>
+  typename ActualAlloc::ResultType Assign(
+      const nsTArray_Impl<E, Allocator>& aOther)
+  {
+    return ActualAlloc::ConvertBoolToResultType(
+      !!ReplaceElementsAt<E, ActualAlloc>(0, Length(),
+                                          aOther.Elements(), aOther.Length()));
+  }
+
+  template<class Allocator>
+  MOZ_MUST_USE
+  bool Assign(const nsTArray_Impl<E, Allocator>& aOther,
+              const mozilla::fallible_t&)
+  {
+    return Assign<Allocator, FallibleAlloc>(aOther);
+  }
+
+  template<class Allocator>
+  void Assign(nsTArray_Impl<E, Allocator>&& aOther)
+  {
+    Clear();
+    SwapElements(aOther);
+  }
+
+  // This method call the destructor on each element of the array, empties it,
+  // but does not shrink the array's capacity.
+  // See also SetLengthAndRetainStorage.
+  // Make sure to call Compact() if needed to avoid keeping a huge array
+  // around.
+  void ClearAndRetainStorage()
+  {
+    if (base_type::mHdr == EmptyHdr()) {
+      return;
+    }
+
+    DestructRange(0, Length());
+    base_type::mHdr->mLength = 0;
+  }
+
+  // This method modifies the length of the array, but unlike SetLength
+  // it doesn't deallocate/reallocate the current internal storage.
+  // The new length MUST be shorter than or equal to the current capacity.
+  // If the new length is larger than the existing length of the array,
+  // then new elements will be constructed using elem_type's default
+  // constructor.  If shorter, elements will be destructed and removed.
+  // See also ClearAndRetainStorage.
+  // @param aNewLen  The desired length of this array.
+  void SetLengthAndRetainStorage(size_type aNewLen)
+  {
+    MOZ_ASSERT(aNewLen <= base_type::Capacity());
+    size_type oldLen = Length();
+    if (aNewLen > oldLen) {
+      InsertElementsAt(oldLen, aNewLen - oldLen);
+      return;
+    }
+    if (aNewLen < oldLen) {
+      DestructRange(aNewLen, oldLen - aNewLen);
+      base_type::mHdr->mLength = aNewLen;
+    }
+  }
+
+  // This method replaces a range of elements in this array.
+  // @param aStart    The starting index of the elements to replace.
+  // @param aCount    The number of elements to replace.  This may be zero to
+  //                  insert elements without removing any existing elements.
+  // @param aArray    The values to copy into this array.  Must be non-null,
+  //                  and these elements must not already exist in the array
+  //                  being modified.
+  // @param aArrayLen The number of values to copy into this array.
+  // @return          A pointer to the new elements in the array, or null if
+  //                  the operation failed due to insufficient memory.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const Item* aArray, size_type aArrayLen);
+
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const Item* aArray, size_type aArrayLen,
+                               const mozilla::fallible_t&)
+  {
+    return ReplaceElementsAt<Item, FallibleAlloc>(aStart, aCount,
+                                                  aArray, aArrayLen);
+  }
+
+  // A variation on the ReplaceElementsAt method defined above.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const nsTArray<Item>& aArray)
+  {
+    return ReplaceElementsAt<Item, ActualAlloc>(
+      aStart, aCount, aArray.Elements(), aArray.Length());
+  }
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const nsTArray<Item>& aArray,
+                               const mozilla::fallible_t&)
+  {
+    return ReplaceElementsAt<Item, FallibleAlloc>(aStart, aCount, aArray);
+  }
+
+  // A variation on the ReplaceElementsAt method defined above.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const Item& aItem)
+  {
+    return ReplaceElementsAt<Item, ActualAlloc>(aStart, aCount, &aItem, 1);
+  }
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const Item& aItem, const mozilla::fallible_t&)
+  {
+    return ReplaceElementsAt<Item, FallibleAlloc>(aStart, aCount, aItem);
+  }
+
+  // A variation on the ReplaceElementsAt method defined above.
+  template<class Item>
+  elem_type* ReplaceElementAt(index_type aIndex, const Item& aItem)
+  {
+    return ReplaceElementsAt(aIndex, 1, &aItem, 1);
+  }
+
+  // A variation on the ReplaceElementsAt method defined above.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* InsertElementsAt(index_type aIndex, const Item* aArray,
+                              size_type aArrayLen)
+  {
+    return ReplaceElementsAt<Item, ActualAlloc>(aIndex, 0, aArray, aArrayLen);
+  }
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* InsertElementsAt(index_type aIndex, const Item* aArray,
+                              size_type aArrayLen, const mozilla::fallible_t&)
+  {
+    return InsertElementsAt<Item, FallibleAlloc>(aIndex, aArray, aArrayLen);
+  }
+
+  // A variation on the ReplaceElementsAt method defined above.
+protected:
+  template<class Item, class Allocator, typename ActualAlloc = Alloc>
+  elem_type* InsertElementsAt(index_type aIndex,
+                              const nsTArray_Impl<Item, Allocator>& aArray)
+  {
+    return ReplaceElementsAt<Item, ActualAlloc>(
+      aIndex, 0, aArray.Elements(), aArray.Length());
+  }
+public:
+
+  template<class Item, class Allocator>
+  MOZ_MUST_USE
+  elem_type* InsertElementsAt(index_type aIndex,
+                              const nsTArray_Impl<Item, Allocator>& aArray,
+                              const mozilla::fallible_t&)
+  {
+    return InsertElementsAt<Item, Allocator, FallibleAlloc>(aIndex, aArray);
+  }
+
+  // Insert a new element without copy-constructing. This is useful to avoid
+  // temporaries.
+  // @return A pointer to the newly inserted element, or null on OOM.
+protected:
+  template<typename ActualAlloc = Alloc>
+  elem_type* InsertElementAt(index_type aIndex);
+
+public:
+
+  MOZ_MUST_USE
+  elem_type* InsertElementAt(index_type aIndex, const mozilla::fallible_t&)
+  {
+    return InsertElementAt<FallibleAlloc>(aIndex);
+  }
+
+  // Insert a new element, move constructing if possible.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* InsertElementAt(index_type aIndex, Item&& aItem);
+
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* InsertElementAt(index_type aIndex, Item&& aItem,
+                             const mozilla::fallible_t&)
+  {
+    return InsertElementAt<Item, FallibleAlloc>(aIndex,
+                                                mozilla::Forward<Item>(aItem));
+  }
+
+  // This method searches for the smallest index of an element that is strictly
+  // greater than |aItem|. If |aItem| is inserted at this index, the array will
+  // remain sorted and |aItem| would come after all elements that are equal to
+  // it. If |aItem| is greater than or equal to all elements in the array, the
+  // array length is returned.
+  //
+  // Note that consumers who want to know whether there are existing items equal
+  // to |aItem| in the array can just check that the return value here is > 0
+  // and indexing into the previous slot gives something equal to |aItem|.
+  //
+  //
+  // @param aItem  The item to search for.
+  // @param aComp  The Comparator used.
+  // @return        The index of greatest element <= to |aItem|
+  // @precondition The array is sorted
+  template<class Item, class Comparator>
+  index_type IndexOfFirstElementGt(const Item& aItem,
+                                   const Comparator& aComp) const
+  {
+    using mozilla::BinarySearchIf;
+    typedef ::detail::ItemComparatorFirstElementGT<Item, Comparator> Cmp;
+
+    size_t index;
+    BinarySearchIf(*this, 0, Length(), Cmp(aItem, aComp), &index);
+    return index;
+  }
+
+  // A variation on the IndexOfFirstElementGt method defined above.
+  template<class Item>
+  index_type
+  IndexOfFirstElementGt(const Item& aItem) const
+  {
+    return IndexOfFirstElementGt(aItem, nsDefaultComparator<elem_type, Item>());
+  }
+
+  // Inserts |aItem| at such an index to guarantee that if the array
+  // was previously sorted, it will remain sorted after this
+  // insertion.
+protected:
+  template<class Item, class Comparator, typename ActualAlloc = Alloc>
+  elem_type* InsertElementSorted(Item&& aItem, const Comparator& aComp)
+  {
+    index_type index = IndexOfFirstElementGt<Item, Comparator>(aItem, aComp);
+    return InsertElementAt<Item, ActualAlloc>(
+      index, mozilla::Forward<Item>(aItem));
+  }
+public:
+
+  template<class Item, class Comparator>
+  MOZ_MUST_USE
+  elem_type* InsertElementSorted(Item&& aItem, const Comparator& aComp,
+                                 const mozilla::fallible_t&)
+  {
+    return InsertElementSorted<Item, Comparator, FallibleAlloc>(
+      mozilla::Forward<Item>(aItem), aComp);
+  }
+
+  // A variation on the InsertElementSorted method defined above.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* InsertElementSorted(Item&& aItem)
+  {
+    nsDefaultComparator<elem_type, Item> comp;
+    return InsertElementSorted<Item, decltype(comp), ActualAlloc>(
+      mozilla::Forward<Item>(aItem), comp);
+  }
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* InsertElementSorted(Item&& aItem, const mozilla::fallible_t&)
+  {
+    return InsertElementSorted<Item, FallibleAlloc>(
+      mozilla::Forward<Item>(aItem));
+  }
+
+  // This method appends elements to the end of this array.
+  // @param aArray    The elements to append to this array.
+  // @param aArrayLen The number of elements to append to this array.
+  // @return          A pointer to the new elements in the array, or null if
+  //                  the operation failed due to insufficient memory.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* AppendElements(const Item* aArray, size_type aArrayLen);
+
+public:
+
+  template<class Item>
+  /* MOZ_MUST_USE */
+  elem_type* AppendElements(const Item* aArray, size_type aArrayLen,
+                            const mozilla::fallible_t&)
+  {
+    return AppendElements<Item, FallibleAlloc>(aArray, aArrayLen);
+  }
+
+  // A variation on the AppendElements method defined above.
+protected:
+  template<class Item, class Allocator, typename ActualAlloc = Alloc>
+  elem_type* AppendElements(const nsTArray_Impl<Item, Allocator>& aArray)
+  {
+    return AppendElements<Item, ActualAlloc>(aArray.Elements(), aArray.Length());
+  }
+public:
+
+  template<class Item, class Allocator>
+  /* MOZ_MUST_USE */
+  elem_type* AppendElements(const nsTArray_Impl<Item, Allocator>& aArray,
+                            const mozilla::fallible_t&)
+  {
+    return AppendElements<Item, Allocator, FallibleAlloc>(aArray);
+  }
+
+  // Move all elements from another array to the end of this array.
+  // @return A pointer to the newly appended elements, or null on OOM.
+protected:
+  template<class Item, class Allocator, typename ActualAlloc = Alloc>
+  elem_type* AppendElements(nsTArray_Impl<Item, Allocator>&& aArray);
+
+public:
+
+  template<class Item, class Allocator, typename ActualAlloc = Alloc>
+  /* MOZ_MUST_USE */
+  elem_type* AppendElements(nsTArray_Impl<Item, Allocator>&& aArray,
+                            const mozilla::fallible_t&)
+  {
+    return AppendElements<Item, Allocator>(mozilla::Move(aArray));
+  }
+
+  // Append a new element, move constructing if possible.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* AppendElement(Item&& aItem);
+
+public:
+
+  template<class Item>
+  /* MOZ_MUST_USE */
+  elem_type* AppendElement(Item&& aItem,
+                           const mozilla::fallible_t&)
+  {
+    return AppendElement<Item, FallibleAlloc>(mozilla::Forward<Item>(aItem));
+  }
+
+  // Append new elements without copy-constructing. This is useful to avoid
+  // temporaries.
+  // @return A pointer to the newly appended elements, or null on OOM.
+protected:
+  template<typename ActualAlloc = Alloc>
+  elem_type* AppendElements(size_type aCount) {
+    if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+          Length() + aCount, sizeof(elem_type)))) {
+      return nullptr;
+    }
+    elem_type* elems = Elements() + Length();
+    size_type i;
+    for (i = 0; i < aCount; ++i) {
+      elem_traits::Construct(elems + i);
+    }
+    this->IncrementLength(aCount);
+    return elems;
+  }
+public:
+
+  /* MOZ_MUST_USE */
+  elem_type* AppendElements(size_type aCount,
+                            const mozilla::fallible_t&)
+  {
+    return AppendElements<FallibleAlloc>(aCount);
+  }
+
+  // Append a new element without copy-constructing. This is useful to avoid
+  // temporaries.
+  // @return A pointer to the newly appended element, or null on OOM.
+protected:
+  template<typename ActualAlloc = Alloc>
+  elem_type* AppendElement()
+  {
+    return AppendElements<ActualAlloc>(1);
+  }
+public:
+
+  /* MOZ_MUST_USE */
+  elem_type* AppendElement(const mozilla::fallible_t&)
+  {
+    return AppendElement<FallibleAlloc>();
+  }
+
+  // This method removes a range of elements from this array.
+  // @param aStart The starting index of the elements to remove.
+  // @param aCount The number of elements to remove.
+  void RemoveElementsAt(index_type aStart, size_type aCount);
+
+  // A variation on the RemoveElementsAt method defined above.
+  void RemoveElementAt(index_type aIndex) { RemoveElementsAt(aIndex, 1); }
+
+  // A variation on the RemoveElementsAt method defined above.
+  void Clear() { RemoveElementsAt(0, Length()); }
+
+  // This method removes elements based on the return value of the
+  // callback function aPredicate. If the function returns true for
+  // an element, the element is removed. aPredicate will be called
+  // for each element in order. It is not safe to access the array
+  // inside aPredicate.
+  template<typename Predicate>
+  void RemoveElementsBy(Predicate aPredicate);
+
+  // This helper function combines IndexOf with RemoveElementAt to "search
+  // and destroy" the first element that is equal to the given element.
+  // @param aItem The item to search for.
+  // @param aComp The Comparator used to determine element equality.
+  // @return true if the element was found
+  template<class Item, class Comparator>
+  bool RemoveElement(const Item& aItem, const Comparator& aComp)
+  {
+    index_type i = IndexOf(aItem, 0, aComp);
+    if (i == NoIndex) {
+      return false;
+    }
+
+    RemoveElementAt(i);
+    return true;
+  }
+
+  // A variation on the RemoveElement method defined above that assumes
+  // that 'operator==' is defined for elem_type.
+  template<class Item>
+  bool RemoveElement(const Item& aItem)
+  {
+    return RemoveElement(aItem, nsDefaultComparator<elem_type, Item>());
+  }
+
+  // This helper function combines IndexOfFirstElementGt with
+  // RemoveElementAt to "search and destroy" the last element that
+  // is equal to the given element.
+  // @param aItem The item to search for.
+  // @param aComp The Comparator used to determine element equality.
+  // @return true if the element was found
+  template<class Item, class Comparator>
+  bool RemoveElementSorted(const Item& aItem, const Comparator& aComp)
+  {
+    index_type index = IndexOfFirstElementGt(aItem, aComp);
+    if (index > 0 && aComp.Equals(ElementAt(index - 1), aItem)) {
+      RemoveElementAt(index - 1);
+      return true;
+    }
+    return false;
+  }
+
+  // A variation on the RemoveElementSorted method defined above.
+  template<class Item>
+  bool RemoveElementSorted(const Item& aItem)
+  {
+    return RemoveElementSorted(aItem, nsDefaultComparator<elem_type, Item>());
+  }
+
+  // This method causes the elements contained in this array and the given
+  // array to be swapped.
+  template<class Allocator>
+  typename Alloc::ResultType SwapElements(nsTArray_Impl<E, Allocator>& aOther)
+  {
+    return Alloc::Result(this->template SwapArrayElements<Alloc>(
+      aOther, sizeof(elem_type), MOZ_ALIGNOF(elem_type)));
+  }
+
+  //
+  // Allocation
+  //
+
+  // This method may increase the capacity of this array object by the
+  // specified amount.  This method may be called in advance of several
+  // AppendElement operations to minimize heap re-allocations.  This method
+  // will not reduce the number of elements in this array.
+  // @param aCapacity The desired capacity of this array.
+  // @return True if the operation succeeded; false if we ran out of memory
+protected:
+  template<typename ActualAlloc = Alloc>
+  typename ActualAlloc::ResultType SetCapacity(size_type aCapacity)
+  {
+    return ActualAlloc::Result(this->template EnsureCapacity<ActualAlloc>(
+      aCapacity, sizeof(elem_type)));
+  }
+public:
+
+  MOZ_MUST_USE
+  bool SetCapacity(size_type aCapacity, const mozilla::fallible_t&)
+  {
+    return SetCapacity<FallibleAlloc>(aCapacity);
+  }
+
+  // This method modifies the length of the array.  If the new length is
+  // larger than the existing length of the array, then new elements will be
+  // constructed using elem_type's default constructor.  Otherwise, this call
+  // removes elements from the array (see also RemoveElementsAt).
+  // @param aNewLen The desired length of this array.
+  // @return True if the operation succeeded; false otherwise.
+  // See also TruncateLength if the new length is guaranteed to be smaller than
+  // the old.
+protected:
+  template<typename ActualAlloc = Alloc>
+  typename ActualAlloc::ResultType SetLength(size_type aNewLen)
+  {
+    size_type oldLen = Length();
+    if (aNewLen > oldLen) {
+      return ActualAlloc::ConvertBoolToResultType(
+        InsertElementsAt<ActualAlloc>(oldLen, aNewLen - oldLen) != nullptr);
+    }
+
+    TruncateLength(aNewLen);
+    return ActualAlloc::ConvertBoolToResultType(true);
+  }
+public:
+
+  MOZ_MUST_USE
+  bool SetLength(size_type aNewLen, const mozilla::fallible_t&)
+  {
+    return SetLength<FallibleAlloc>(aNewLen);
+  }
+
+  // This method modifies the length of the array, but may only be
+  // called when the new length is shorter than the old.  It can
+  // therefore be called when elem_type has no default constructor,
+  // unlike SetLength.  It removes elements from the array (see also
+  // RemoveElementsAt).
+  // @param aNewLen The desired length of this array.
+  void TruncateLength(size_type aNewLen)
+  {
+    size_type oldLen = Length();
+    MOZ_ASSERT(aNewLen <= oldLen,
+               "caller should use SetLength instead");
+    RemoveElementsAt(aNewLen, oldLen - aNewLen);
+  }
+
+  // This method ensures that the array has length at least the given
+  // length.  If the current length is shorter than the given length,
+  // then new elements will be constructed using elem_type's default
+  // constructor.
+  // @param aMinLen The desired minimum length of this array.
+  // @return True if the operation succeeded; false otherwise.
+protected:
+  template<typename ActualAlloc = Alloc>
+  typename ActualAlloc::ResultType EnsureLengthAtLeast(size_type aMinLen)
+  {
+    size_type oldLen = Length();
+    if (aMinLen > oldLen) {
+      return ActualAlloc::ConvertBoolToResultType(
+        !!InsertElementsAt<ActualAlloc>(oldLen, aMinLen - oldLen));
+    }
+    return ActualAlloc::ConvertBoolToResultType(true);
+  }
+public:
+
+  MOZ_MUST_USE
+  bool EnsureLengthAtLeast(size_type aMinLen, const mozilla::fallible_t&)
+  {
+    return EnsureLengthAtLeast<FallibleAlloc>(aMinLen);
+  }
+
+  // This method inserts elements into the array, constructing
+  // them using elem_type's default constructor.
+  // @param aIndex the place to insert the new elements. This must be no
+  //               greater than the current length of the array.
+  // @param aCount the number of elements to insert
+protected:
+  template<typename ActualAlloc = Alloc>
+  elem_type* InsertElementsAt(index_type aIndex, size_type aCount)
+  {
+    if (!base_type::template InsertSlotsAt<ActualAlloc>(aIndex, aCount,
+                                                        sizeof(elem_type),
+                                                        MOZ_ALIGNOF(elem_type))) {
+      return nullptr;
+    }
+
+    // Initialize the extra array elements
+    elem_type* iter = Elements() + aIndex;
+    elem_type* iend = iter + aCount;
+    for (; iter != iend; ++iter) {
+      elem_traits::Construct(iter);
+    }
+
+    return Elements() + aIndex;
+  }
+public:
+
+  MOZ_MUST_USE
+  elem_type* InsertElementsAt(index_type aIndex, size_type aCount,
+                              const mozilla::fallible_t&)
+  {
+    return InsertElementsAt<FallibleAlloc>(aIndex, aCount);
+  }
+
+  // This method inserts elements into the array, constructing them
+  // elem_type's copy constructor (or whatever one-arg constructor
+  // happens to match the Item type).
+  // @param aIndex the place to insert the new elements. This must be no
+  //               greater than the current length of the array.
+  // @param aCount the number of elements to insert.
+  // @param aItem the value to use when constructing the new elements.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* InsertElementsAt(index_type aIndex, size_type aCount,
+                              const Item& aItem);
+
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* InsertElementsAt(index_type aIndex, size_type aCount,
+                              const Item& aItem, const mozilla::fallible_t&)
+  {
+    return InsertElementsAt<Item, FallibleAlloc>(aIndex, aCount, aItem);
+  }
+
+  // This method may be called to minimize the memory used by this array.
+  void Compact()
+  {
+    ShrinkCapacity(sizeof(elem_type), MOZ_ALIGNOF(elem_type));
+  }
+
+  //
+  // Sorting
+  //
+
+  // This function is meant to be used with the NS_QuickSort function.  It
+  // maps the callback API expected by NS_QuickSort to the Comparator API
+  // used by nsTArray_Impl.  See nsTArray_Impl::Sort.
+  template<class Comparator>
+  static int Compare(const void* aE1, const void* aE2, void* aData)
+  {
+    const Comparator* c = reinterpret_cast<const Comparator*>(aData);
+    const elem_type* a = static_cast<const elem_type*>(aE1);
+    const elem_type* b = static_cast<const elem_type*>(aE2);
+    return c->LessThan(*a, *b) ? -1 : (c->Equals(*a, *b) ? 0 : 1);
+  }
+
+  // This method sorts the elements of the array.  It uses the LessThan
+  // method defined on the given Comparator object to collate elements.
+  // @param aComp The Comparator used to collate elements.
+  template<class Comparator>
+  void Sort(const Comparator& aComp)
+  {
+    NS_QuickSort(Elements(), Length(), sizeof(elem_type),
+                 Compare<Comparator>, const_cast<Comparator*>(&aComp));
+  }
+
+  // A variation on the Sort method defined above that assumes that
+  // 'operator<' is defined for elem_type.
+  void Sort() { Sort(nsDefaultComparator<elem_type, elem_type>()); }
+
+protected:
+  using base_type::Hdr;
+  using base_type::ShrinkCapacity;
+
+  // This method invokes elem_type's destructor on a range of elements.
+  // @param aStart The index of the first element to destroy.
+  // @param aCount The number of elements to destroy.
+  void DestructRange(index_type aStart, size_type aCount)
+  {
+    elem_type* iter = Elements() + aStart;
+    elem_type *iend = iter + aCount;
+    for (; iter != iend; ++iter) {
+      elem_traits::Destruct(iter);
+    }
+  }
+
+  // This method invokes elem_type's copy-constructor on a range of elements.
+  // @param aStart  The index of the first element to construct.
+  // @param aCount  The number of elements to construct.
+  // @param aValues The array of elements to copy.
+  template<class Item>
+  void AssignRange(index_type aStart, size_type aCount, const Item* aValues)
+  {
+    AssignRangeAlgorithm<mozilla::IsPod<Item>::value,
+                         mozilla::IsSame<Item, elem_type>::value>
+                         ::implementation(Elements(), aStart, aCount, aValues);
+  }
+};
+
+template<typename E, class Alloc>
+template<class Item, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::ReplaceElementsAt(index_type aStart, size_type aCount,
+                                           const Item* aArray, size_type aArrayLen) -> elem_type*
+{
+  // Adjust memory allocation up-front to catch errors.
+  if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+        Length() + aArrayLen - aCount, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  DestructRange(aStart, aCount);
+  this->template ShiftData<ActualAlloc>(aStart, aCount, aArrayLen,
+                                        sizeof(elem_type),
+                                        MOZ_ALIGNOF(elem_type));
+  AssignRange(aStart, aArrayLen, aArray);
+  return Elements() + aStart;
+}
+
+template<typename E, class Alloc>
+void
+nsTArray_Impl<E, Alloc>::RemoveElementsAt(index_type aStart, size_type aCount)
+{
+  MOZ_ASSERT(aCount == 0 || aStart < Length(), "Invalid aStart index");
+  MOZ_ASSERT(aStart + aCount <= Length(), "Invalid length");
+  // Check that the previous assert didn't overflow
+  MOZ_ASSERT(aStart <= aStart + aCount, "Start index plus length overflows");
+  DestructRange(aStart, aCount);
+  this->template ShiftData<InfallibleAlloc>(aStart, aCount, 0,
+                                            sizeof(elem_type),
+                                            MOZ_ALIGNOF(elem_type));
+}
+
+template<typename E, class Alloc>
+template<typename Predicate>
+void
+nsTArray_Impl<E, Alloc>::RemoveElementsBy(Predicate aPredicate)
+{
+  if (base_type::mHdr == EmptyHdr()) {
+    return;
+  }
+
+  index_type j = 0;
+  index_type len = Length();
+  for (index_type i = 0; i < len; ++i) {
+    if (aPredicate(Elements()[i])) {
+      elem_traits::Destruct(Elements() + i);
+    } else {
+      if (j < i) {
+        copy_type::MoveNonOverlappingRegion(Elements() + j, Elements() + i,
+                                            1, sizeof(elem_type));
+      }
+      ++j;
+    }
+  }
+  base_type::mHdr->mLength = j;
+}
+
+template<typename E, class Alloc>
+template<class Item, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::InsertElementsAt(index_type aIndex, size_type aCount,
+                                          const Item& aItem) -> elem_type*
+{
+  if (!base_type::template InsertSlotsAt<ActualAlloc>(aIndex, aCount,
+                                                      sizeof(elem_type),
+                                                      MOZ_ALIGNOF(elem_type))) {
+    return nullptr;
+  }
+
+  // Initialize the extra array elements
+  elem_type* iter = Elements() + aIndex;
+  elem_type* iend = iter + aCount;
+  for (; iter != iend; ++iter) {
+    elem_traits::Construct(iter, aItem);
+  }
+
+  return Elements() + aIndex;
+}
+
+template<typename E, class Alloc>
+template<typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::InsertElementAt(index_type aIndex) -> elem_type*
+{
+  if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+        Length() + 1, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  this->template ShiftData<ActualAlloc>(aIndex, 0, 1, sizeof(elem_type),
+                                        MOZ_ALIGNOF(elem_type));
+  elem_type* elem = Elements() + aIndex;
+  elem_traits::Construct(elem);
+  return elem;
+}
+
+template<typename E, class Alloc>
+template<class Item, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::InsertElementAt(index_type aIndex, Item&& aItem) -> elem_type*
+{
+  if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+         Length() + 1, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  this->template ShiftData<ActualAlloc>(aIndex, 0, 1, sizeof(elem_type),
+                                        MOZ_ALIGNOF(elem_type));
+  elem_type* elem = Elements() + aIndex;
+  elem_traits::Construct(elem, mozilla::Forward<Item>(aItem));
+  return elem;
+}
+
+template<typename E, class Alloc>
+template<class Item, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::AppendElements(const Item* aArray, size_type aArrayLen) -> elem_type*
+{
+  if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+        Length() + aArrayLen, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  index_type len = Length();
+  AssignRange(len, aArrayLen, aArray);
+  this->IncrementLength(aArrayLen);
+  return Elements() + len;
+}
+
+template<typename E, class Alloc>
+template<class Item, class Allocator, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::AppendElements(nsTArray_Impl<Item, Allocator>&& aArray) -> elem_type*
+{
+  MOZ_ASSERT(&aArray != this, "argument must be different aArray");
+  if (Length() == 0) {
+    SwapElements<ActualAlloc>(aArray);
+    return Elements();
+  }
+
+  index_type len = Length();
+  index_type otherLen = aArray.Length();
+  if (!Alloc::Successful(this->template EnsureCapacity<Alloc>(
+        len + otherLen, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  copy_type::MoveNonOverlappingRegion(Elements() + len, aArray.Elements(), otherLen,
+                                      sizeof(elem_type));
+  this->IncrementLength(otherLen);
+  aArray.template ShiftData<Alloc>(0, otherLen, 0, sizeof(elem_type),
+                                   MOZ_ALIGNOF(elem_type));
+  return Elements() + len;
+}
+
+template<typename E, class Alloc>
+template<class Item, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::AppendElement(Item&& aItem) -> elem_type*
+{
+  if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+         Length() + 1, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  elem_type* elem = Elements() + Length();
+  elem_traits::Construct(elem, mozilla::Forward<Item>(aItem));
+  this->IncrementLength(1);
+  return elem;
+}
+
+template<typename E, typename Alloc>
+inline void
+ImplCycleCollectionUnlink(nsTArray_Impl<E, Alloc>& aField)
+{
+  aField.Clear();
+}
+
+template<typename E, typename Alloc>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsTArray_Impl<E, Alloc>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  aFlags |= CycleCollectionEdgeNameArrayFlag;
+  size_t length = aField.Length();
+  for (size_t i = 0; i < length; ++i) {
+    ImplCycleCollectionTraverse(aCallback, aField[i], aName, aFlags);
+  }
+}
+
+//
+// nsTArray is an infallible vector class.  See the comment at the top of this
+// file for more details.
+//
+template<class E>
+class nsTArray : public nsTArray_Impl<E, nsTArrayInfallibleAllocator>
+{
+public:
+  typedef nsTArray_Impl<E, nsTArrayInfallibleAllocator> base_type;
+  typedef nsTArray<E>                                   self_type;
+  typedef typename base_type::size_type                 size_type;
+
+  nsTArray() {}
+  explicit nsTArray(size_type aCapacity) : base_type(aCapacity) {}
+  explicit nsTArray(const nsTArray& aOther) : base_type(aOther) {}
+  MOZ_IMPLICIT nsTArray(nsTArray&& aOther) : base_type(mozilla::Move(aOther)) {}
+  MOZ_IMPLICIT nsTArray(std::initializer_list<E> aIL) : base_type(aIL) {}
+
+  template<class Allocator>
+  explicit nsTArray(const nsTArray_Impl<E, Allocator>& aOther)
+    : base_type(aOther)
+  {
+  }
+  template<class Allocator>
+  MOZ_IMPLICIT nsTArray(nsTArray_Impl<E, Allocator>&& aOther)
+    : base_type(mozilla::Move(aOther))
+  {
+  }
+
+  self_type& operator=(const self_type& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+  template<class Allocator>
+  self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+  self_type& operator=(self_type&& aOther)
+  {
+    base_type::operator=(mozilla::Move(aOther));
+    return *this;
+  }
+  template<class Allocator>
+  self_type& operator=(nsTArray_Impl<E, Allocator>&& aOther)
+  {
+    base_type::operator=(mozilla::Move(aOther));
+    return *this;
+  }
+
+  using base_type::AppendElement;
+  using base_type::AppendElements;
+  using base_type::EnsureLengthAtLeast;
+  using base_type::InsertElementAt;
+  using base_type::InsertElementsAt;
+  using base_type::InsertElementSorted;
+  using base_type::ReplaceElementsAt;
+  using base_type::SetCapacity;
+  using base_type::SetLength;
+};
+
+//
+// FallibleTArray is a fallible vector class.
+//
+template<class E>
+class FallibleTArray : public nsTArray_Impl<E, nsTArrayFallibleAllocator>
+{
+public:
+  typedef nsTArray_Impl<E, nsTArrayFallibleAllocator>   base_type;
+  typedef FallibleTArray<E>                             self_type;
+  typedef typename base_type::size_type                 size_type;
+
+  FallibleTArray() {}
+  explicit FallibleTArray(size_type aCapacity) : base_type(aCapacity) {}
+  explicit FallibleTArray(const FallibleTArray<E>& aOther) : base_type(aOther) {}
+  FallibleTArray(FallibleTArray<E>&& aOther)
+    : base_type(mozilla::Move(aOther))
+  {
+  }
+
+  template<class Allocator>
+  explicit FallibleTArray(const nsTArray_Impl<E, Allocator>& aOther)
+    : base_type(aOther)
+  {
+  }
+  template<class Allocator>
+  explicit FallibleTArray(nsTArray_Impl<E, Allocator>&& aOther)
+    : base_type(mozilla::Move(aOther))
+  {
+  }
+
+  self_type& operator=(const self_type& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+  template<class Allocator>
+  self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+  self_type& operator=(self_type&& aOther)
+  {
+    base_type::operator=(mozilla::Move(aOther));
+    return *this;
+  }
+  template<class Allocator>
+  self_type& operator=(nsTArray_Impl<E, Allocator>&& aOther)
+  {
+    base_type::operator=(mozilla::Move(aOther));
+    return *this;
+  }
+};
+
+//
+// AutoTArray<E, N> is like nsTArray<E>, but with N elements of inline storage.
+// Storing more than N elements is fine, but it will cause a heap allocation.
+//
+template<class E, size_t N>
+class MOZ_NON_MEMMOVABLE AutoTArray : public nsTArray<E>
+{
+  static_assert(N != 0, "AutoTArray<E, 0> should be specialized");
+public:
+  typedef AutoTArray<E, N> self_type;
+  typedef nsTArray<E> base_type;
+  typedef typename base_type::Header Header;
+  typedef typename base_type::elem_type elem_type;
+
+  AutoTArray()
+  {
+    Init();
+  }
+
+  AutoTArray(const self_type& aOther)
+  {
+    Init();
+    this->AppendElements(aOther);
+  }
+
+  explicit AutoTArray(const base_type& aOther)
+  {
+    Init();
+    this->AppendElements(aOther);
+  }
+
+  explicit AutoTArray(base_type&& aOther)
+  {
+    Init();
+    this->SwapElements(aOther);
+  }
+
+  template<typename Allocator>
+  explicit AutoTArray(nsTArray_Impl<elem_type, Allocator>&& aOther)
+  {
+    Init();
+    this->SwapElements(aOther);
+  }
+
+  MOZ_IMPLICIT AutoTArray(std::initializer_list<E> aIL)
+  {
+    Init();
+    this->AppendElements(aIL.begin(), aIL.size());
+  }
+
+  self_type& operator=(const self_type& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+
+  template<typename Allocator>
+  self_type& operator=(const nsTArray_Impl<elem_type, Allocator>& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+
+private:
+  // nsTArray_base casts itself as an nsAutoArrayBase in order to get a pointer
+  // to mAutoBuf.
+  template<class Allocator, class Copier>
+  friend class nsTArray_base;
+
+  void Init()
+  {
+    static_assert(MOZ_ALIGNOF(elem_type) <= 8,
+                  "can't handle alignments greater than 8, "
+                  "see nsTArray_base::UsesAutoArrayBuffer()");
+    // Temporary work around for VS2012 RC compiler crash
+    Header** phdr = base_type::PtrToHdr();
+    *phdr = reinterpret_cast<Header*>(&mAutoBuf);
+    (*phdr)->mLength = 0;
+    (*phdr)->mCapacity = N;
+    (*phdr)->mIsAutoArray = 1;
+
+    MOZ_ASSERT(base_type::GetAutoArrayBuffer(MOZ_ALIGNOF(elem_type)) ==
+               reinterpret_cast<Header*>(&mAutoBuf),
+               "GetAutoArrayBuffer needs to be fixed");
+  }
+
+  // Declare mAutoBuf aligned to the maximum of the header's alignment and
+  // elem_type's alignment.  We need to use a union rather than
+  // MOZ_ALIGNED_DECL because GCC is picky about what goes into
+  // __attribute__((aligned(foo))).
+  union
+  {
+    char mAutoBuf[sizeof(nsTArrayHeader) + N * sizeof(elem_type)];
+    // Do the max operation inline to ensure that it is a compile-time constant.
+    mozilla::AlignedElem<(MOZ_ALIGNOF(Header) > MOZ_ALIGNOF(elem_type)) ?
+                         MOZ_ALIGNOF(Header) : MOZ_ALIGNOF(elem_type)> mAlign;
+  };
+};
+
+//
+// Specialization of AutoTArray<E, N> for the case where N == 0.
+// AutoTArray<E, 0> behaves exactly like nsTArray<E>, but without this
+// specialization, it stores a useless inline header.
+//
+// We do have many AutoTArray<E, 0> objects in memory: about 2,000 per tab as
+// of May 2014. These are typically not explicitly AutoTArray<E, 0> but rather
+// AutoTArray<E, N> for some value N depending on template parameters, in
+// generic code.
+//
+// For that reason, we optimize this case with the below partial specialization,
+// which ensures that AutoTArray<E, 0> is just like nsTArray<E>, without any
+// inline header overhead.
+//
+template<class E>
+class AutoTArray<E, 0> : public nsTArray<E>
+{
+};
+
+template<class E, size_t N>
+struct nsTArray_CopyChooser<AutoTArray<E, N>>
+{
+  typedef nsTArray_CopyWithConstructors<AutoTArray<E, N>> Type;
+};
+
+// Assert that AutoTArray doesn't have any extra padding inside.
+//
+// It's important that the data stored in this auto array takes up a multiple of
+// 8 bytes; e.g. AutoTArray<uint32_t, 1> wouldn't work.  Since AutoTArray
+// contains a pointer, its size must be a multiple of alignof(void*).  (This is
+// because any type may be placed into an array, and there's no padding between
+// elements of an array.)  The compiler pads the end of the structure to
+// enforce this rule.
+//
+// If we used AutoTArray<uint32_t, 1> below, this assertion would fail on a
+// 64-bit system, where the compiler inserts 4 bytes of padding at the end of
+// the auto array to make its size a multiple of alignof(void*) == 8 bytes.
+
+static_assert(sizeof(AutoTArray<uint32_t, 2>) ==
+              sizeof(void*) + sizeof(nsTArrayHeader) + sizeof(uint32_t) * 2,
+              "AutoTArray shouldn't contain any extra padding, "
+              "see the comment");
+
+// Definitions of nsTArray_Impl methods
+#include "nsTArray-inl.h"
+
+#endif  // nsTArray_h__
diff --git a/xpcom/glue/nsTArrayForwardDeclare.h b/xpcom/glue/nsTArrayForwardDeclare.h
new file mode 100644
index 0000000000..f63ef5f59c
--- /dev/null
+++ b/xpcom/glue/nsTArrayForwardDeclare.h
@@ -0,0 +1,36 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTArrayForwardDeclare_h__
+#define nsTArrayForwardDeclare_h__
+
+//
+// This simple header file contains forward declarations for the TArray family
+// of classes.
+//
+// Including this header is preferable to writing
+//
+//   template<class E> class nsTArray;
+//
+// yourself, since this header gives us flexibility to e.g. change the default
+// template parameters.
+//
+
+#include <stddef.h>
+
+template<class E>
+class nsTArray;
+
+template<class E>
+class FallibleTArray;
+
+template<class E, size_t N>
+class AutoTArray;
+
+template<class E>
+using InfallibleTArray = nsTArray<E>;
+
+#endif
diff --git a/xpcom/glue/nsTHashtable.h b/xpcom/glue/nsTHashtable.h
new file mode 100644
index 0000000000..705b0294e2
--- /dev/null
+++ b/xpcom/glue/nsTHashtable.h
@@ -0,0 +1,577 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTHashtable_h__
+#define nsTHashtable_h__
+
+#include "PLDHashTable.h"
+#include "nsPointerHashKeys.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/fallible.h"
+#include "mozilla/MemoryChecking.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Move.h"
+#include "mozilla/OperatorNewExtensions.h"
+#include "mozilla/PodOperations.h"
+#include "mozilla/TypeTraits.h"
+
+#include <new>
+
+/**
+ * a base class for templated hashtables.
+ *
+ * Clients will rarely need to use this class directly. Check the derived
+ * classes first, to see if they will meet your needs.
+ *
+ * @param EntryType  the templated entry-type class that is managed by the
+ *   hashtable. <code>EntryType</code> must extend the following declaration,
+ *   and <strong>must not declare any virtual functions or derive from classes
+ *   with virtual functions.</strong>  Any vtable pointer would break the
+ *   PLDHashTable code.
+ *<pre>   class EntryType : public PLDHashEntryHdr
+ *   {
+ *   public: or friend nsTHashtable<EntryType>;
+ *     // KeyType is what we use when Get()ing or Put()ing this entry
+ *     // this should either be a simple datatype (uint32_t, nsISupports*) or
+ *     // a const reference (const nsAString&)
+ *     typedef something KeyType;
+ *     // KeyTypePointer is the pointer-version of KeyType, because
+ *     // PLDHashTable.h requires keys to cast to <code>const void*</code>
+ *     typedef const something* KeyTypePointer;
+ *
+ *     EntryType(KeyTypePointer aKey);
+ *
+ *     // A copy or C++11 Move constructor must be defined, even if
+ *     // AllowMemMove() == true, otherwise you will cause link errors.
+ *     EntryType(const EntryType& aEnt);  // Either this...
+ *     EntryType(EntryType&& aEnt);       // ...or this
+ *
+ *     // the destructor must be defined... or you will cause link errors!
+ *     ~EntryType();
+ *
+ *     // KeyEquals(): does this entry match this key?
+ *     bool KeyEquals(KeyTypePointer aKey) const;
+ *
+ *     // KeyToPointer(): Convert KeyType to KeyTypePointer
+ *     static KeyTypePointer KeyToPointer(KeyType aKey);
+ *
+ *     // HashKey(): calculate the hash number
+ *     static PLDHashNumber HashKey(KeyTypePointer aKey);
+ *
+ *     // ALLOW_MEMMOVE can we move this class with memmove(), or do we have
+ *     // to use the copy constructor?
+ *     enum { ALLOW_MEMMOVE = true/false };
+ *   }</pre>
+ *
+ * @see nsInterfaceHashtable
+ * @see nsDataHashtable
+ * @see nsClassHashtable
+ * @author "Benjamin Smedberg <bsmedberg@covad.net>"
+ */
+
+template<class EntryType>
+class MOZ_NEEDS_NO_VTABLE_TYPE nsTHashtable
+{
+  typedef mozilla::fallible_t fallible_t;
+  static_assert(mozilla::IsPointer<typename EntryType::KeyTypePointer>::value,
+                "KeyTypePointer should be a pointer");
+
+public:
+  // Separate constructors instead of default aInitLength parameter since
+  // otherwise the default no-arg constructor isn't found.
+  nsTHashtable()
+    : mTable(Ops(), sizeof(EntryType), PLDHashTable::kDefaultInitialLength)
+  {}
+  explicit nsTHashtable(uint32_t aInitLength)
+    : mTable(Ops(), sizeof(EntryType), aInitLength)
+  {}
+
+  /**
+   * destructor, cleans up and deallocates
+   */
+  ~nsTHashtable();
+
+  nsTHashtable(nsTHashtable<EntryType>&& aOther);
+
+  /**
+   * Return the generation number for the table. This increments whenever
+   * the table data items are moved.
+   */
+  uint32_t GetGeneration() const { return mTable.Generation(); }
+
+  /**
+   * KeyType is typedef'ed for ease of use.
+   */
+  typedef typename EntryType::KeyType KeyType;
+
+  /**
+   * KeyTypePointer is typedef'ed for ease of use.
+   */
+  typedef typename EntryType::KeyTypePointer KeyTypePointer;
+
+  /**
+   * Return the number of entries in the table.
+   * @return    number of entries
+   */
+  uint32_t Count() const { return mTable.EntryCount(); }
+
+  /**
+   * Return true if the hashtable is empty.
+   */
+  bool IsEmpty() const { return Count() == 0; }
+
+  /**
+   * Get the entry associated with a key.
+   * @param     aKey the key to retrieve
+   * @return    pointer to the entry class, if the key exists; nullptr if the
+   *            key doesn't exist
+   */
+  EntryType* GetEntry(KeyType aKey) const
+  {
+    return static_cast<EntryType*>(
+      const_cast<PLDHashTable*>(&mTable)->Search(EntryType::KeyToPointer(aKey)));
+  }
+
+  /**
+   * Return true if an entry for the given key exists, false otherwise.
+   * @param     aKey the key to retrieve
+   * @return    true if the key exists, false if the key doesn't exist
+   */
+  bool Contains(KeyType aKey) const { return !!GetEntry(aKey); }
+
+  /**
+   * Get the entry associated with a key, or create a new entry,
+   * @param     aKey the key to retrieve
+   * @return    pointer to the entry class retreived; nullptr only if memory
+                can't be allocated
+   */
+  EntryType* PutEntry(KeyType aKey)
+  {
+    // infallible add
+    return static_cast<EntryType*>(mTable.Add(EntryType::KeyToPointer(aKey)));
+  }
+
+  MOZ_MUST_USE
+  EntryType* PutEntry(KeyType aKey, const fallible_t&)
+  {
+    return static_cast<EntryType*>(mTable.Add(EntryType::KeyToPointer(aKey),
+                                              mozilla::fallible));
+  }
+
+  /**
+   * Remove the entry associated with a key.
+   * @param     aKey of the entry to remove
+   */
+  void RemoveEntry(KeyType aKey)
+  {
+    mTable.Remove(EntryType::KeyToPointer(aKey));
+  }
+
+  /**
+   * Remove the entry associated with a key.
+   * @param aEntry   the entry-pointer to remove (obtained from GetEntry)
+   */
+  void RemoveEntry(EntryType* aEntry)
+  {
+    mTable.RemoveEntry(aEntry);
+  }
+
+  /**
+   * Remove the entry associated with a key, but don't resize the hashtable.
+   * This is a low-level method, and is not recommended unless you know what
+   * you're doing. If you use it, please add a comment explaining why you
+   * didn't use RemoveEntry().
+   * @param aEntry   the entry-pointer to remove (obtained from GetEntry)
+   */
+  void RawRemoveEntry(EntryType* aEntry)
+  {
+    mTable.RawRemove(aEntry);
+  }
+
+  // This is an iterator that also allows entry removal. Example usage:
+  //
+  //   for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {
+  //     Entry* entry = iter.Get();
+  //     // ... do stuff with |entry| ...
+  //     // ... possibly call iter.Remove() once ...
+  //   }
+  //
+  class Iterator : public PLDHashTable::Iterator
+  {
+  public:
+    typedef PLDHashTable::Iterator Base;
+
+    explicit Iterator(nsTHashtable* aTable) : Base(&aTable->mTable) {}
+    Iterator(Iterator&& aOther) : Base(aOther.mTable) {}
+    ~Iterator() {}
+
+    EntryType* Get() const { return static_cast<EntryType*>(Base::Get()); }
+
+  private:
+    Iterator() = delete;
+    Iterator(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&&) = delete;
+  };
+
+  Iterator Iter() { return Iterator(this); }
+
+  Iterator ConstIter() const
+  {
+    return Iterator(const_cast<nsTHashtable*>(this));
+  }
+
+  /**
+   * Remove all entries, return hashtable to "pristine" state. It's
+   * conceptually the same as calling the destructor and then re-calling the
+   * constructor.
+   */
+  void Clear()
+  {
+    mTable.Clear();
+  }
+
+  /**
+   * Measure the size of the table's entry storage. Does *not* measure anything
+   * hanging off table entries; hence the "Shallow" prefix. To measure that,
+   * either use SizeOfExcludingThis() or iterate manually over the entries,
+   * calling SizeOfExcludingThis() on each one.
+   *
+   * @param     aMallocSizeOf the function used to measure heap-allocated blocks
+   * @return    the measured shallow size of the table
+   */
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return mTable.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * Like ShallowSizeOfExcludingThis, but includes sizeof(*this).
+   */
+  size_t ShallowSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * This is a "deep" measurement of the table. To use it, |EntryType| must
+   * define SizeOfExcludingThis, and that method will be called on all live
+   * entries.
+   */
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    size_t n = ShallowSizeOfExcludingThis(aMallocSizeOf);
+    for (auto iter = ConstIter(); !iter.Done(); iter.Next()) {
+      n += (*iter.Get()).SizeOfExcludingThis(aMallocSizeOf);
+    }
+    return n;
+  }
+
+  /**
+   * Like SizeOfExcludingThis, but includes sizeof(*this).
+   */
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * Swap the elements in this hashtable with the elements in aOther.
+   */
+  void SwapElements(nsTHashtable<EntryType>& aOther)
+  {
+    MOZ_ASSERT_IF(this->mTable.Ops() && aOther.mTable.Ops(),
+                  this->mTable.Ops() == aOther.mTable.Ops());
+    mozilla::Swap(this->mTable, aOther.mTable);
+  }
+
+#ifdef DEBUG
+  /**
+   * Mark the table as constant after initialization.
+   *
+   * This will prevent assertions when a read-only hash is accessed on multiple
+   * threads without synchronization.
+   */
+  void MarkImmutable()
+  {
+    mTable.MarkImmutable();
+  }
+#endif
+
+protected:
+  PLDHashTable mTable;
+
+  static PLDHashNumber s_HashKey(const void* aKey);
+
+  static bool s_MatchEntry(const PLDHashEntryHdr* aEntry,
+                           const void* aKey);
+
+  static void s_CopyEntry(PLDHashTable* aTable, const PLDHashEntryHdr* aFrom,
+                          PLDHashEntryHdr* aTo);
+
+  static void s_ClearEntry(PLDHashTable* aTable, PLDHashEntryHdr* aEntry);
+
+  static void s_InitEntry(PLDHashEntryHdr* aEntry, const void* aKey);
+
+private:
+  // copy constructor, not implemented
+  nsTHashtable(nsTHashtable<EntryType>& aToCopy) = delete;
+
+  /**
+   * Gets the table's ops.
+   */
+  static const PLDHashTableOps* Ops();
+
+  // assignment operator, not implemented
+  nsTHashtable<EntryType>& operator=(nsTHashtable<EntryType>& aToEqual) = delete;
+};
+
+//
+// template definitions
+//
+
+template<class EntryType>
+nsTHashtable<EntryType>::nsTHashtable(nsTHashtable<EntryType>&& aOther)
+  : mTable(mozilla::Move(aOther.mTable))
+{
+  // aOther shouldn't touch mTable after this, because we've stolen the table's
+  // pointers but not overwitten them.
+  MOZ_MAKE_MEM_UNDEFINED(&aOther.mTable, sizeof(aOther.mTable));
+}
+
+template<class EntryType>
+nsTHashtable<EntryType>::~nsTHashtable()
+{
+}
+
+template<class EntryType>
+/* static */ const PLDHashTableOps*
+nsTHashtable<EntryType>::Ops()
+{
+  // If this variable is a global variable, we get strange start-up failures on
+  // WindowsCrtPatch.h (see bug 1166598 comment 20). But putting it inside a
+  // function avoids that problem.
+  static const PLDHashTableOps sOps =
+  {
+    s_HashKey,
+    s_MatchEntry,
+    EntryType::ALLOW_MEMMOVE ? PLDHashTable::MoveEntryStub : s_CopyEntry,
+    s_ClearEntry,
+    s_InitEntry
+  };
+  return &sOps;
+}
+
+// static definitions
+
+template<class EntryType>
+PLDHashNumber
+nsTHashtable<EntryType>::s_HashKey(const void* aKey)
+{
+  return EntryType::HashKey(static_cast<const KeyTypePointer>(aKey));
+}
+
+template<class EntryType>
+bool
+nsTHashtable<EntryType>::s_MatchEntry(const PLDHashEntryHdr* aEntry,
+                                      const void* aKey)
+{
+  return ((const EntryType*)aEntry)->KeyEquals(
+    static_cast<const KeyTypePointer>(aKey));
+}
+
+template<class EntryType>
+void
+nsTHashtable<EntryType>::s_CopyEntry(PLDHashTable* aTable,
+                                     const PLDHashEntryHdr* aFrom,
+                                     PLDHashEntryHdr* aTo)
+{
+  EntryType* fromEntry =
+    const_cast<EntryType*>(static_cast<const EntryType*>(aFrom));
+
+  new (mozilla::KnownNotNull, aTo) EntryType(mozilla::Move(*fromEntry));
+
+  fromEntry->~EntryType();
+}
+
+template<class EntryType>
+void
+nsTHashtable<EntryType>::s_ClearEntry(PLDHashTable* aTable,
+                                      PLDHashEntryHdr* aEntry)
+{
+  static_cast<EntryType*>(aEntry)->~EntryType();
+}
+
+template<class EntryType>
+void
+nsTHashtable<EntryType>::s_InitEntry(PLDHashEntryHdr* aEntry,
+                                     const void* aKey)
+{
+  new (mozilla::KnownNotNull, aEntry) EntryType(static_cast<KeyTypePointer>(aKey));
+}
+
+class nsCycleCollectionTraversalCallback;
+
+template<class EntryType>
+inline void
+ImplCycleCollectionUnlink(nsTHashtable<EntryType>& aField)
+{
+  aField.Clear();
+}
+
+template<class EntryType>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsTHashtable<EntryType>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  for (auto iter = aField.Iter(); !iter.Done(); iter.Next()) {
+    EntryType* entry = iter.Get();
+    ImplCycleCollectionTraverse(aCallback, *entry, aName, aFlags);
+  }
+}
+
+/**
+ * For nsTHashtable with pointer entries, we can have a template specialization
+ * that layers a typed T* interface on top of a common implementation that
+ * works internally with void pointers.  This arrangement saves code size and
+ * might slightly improve performance as well.
+ */
+
+/**
+ * We need a separate entry type class for the inheritance structure of the
+ * nsTHashtable specialization below; nsVoidPtrHashKey is simply typedefed to a
+ * specialization of nsPtrHashKey, and the formulation:
+ *
+ * class nsTHashtable<nsPtrHashKey<T>> : protected nsTHashtable<nsPtrHashKey<const void>
+ *
+ * is not going to turn out very well, since we'd wind up with an nsTHashtable
+ * instantiation that is its own base class.
+ */
+namespace detail {
+
+class VoidPtrHashKey : public nsPtrHashKey<const void>
+{
+  typedef nsPtrHashKey<const void> Base;
+
+public:
+  explicit VoidPtrHashKey(const void* aKey) : Base(aKey) {}
+};
+
+} // namespace detail
+
+/**
+ * See the main nsTHashtable documentation for descriptions of this class's
+ * methods.
+ */
+template<typename T>
+class nsTHashtable<nsPtrHashKey<T>> : protected nsTHashtable<::detail::VoidPtrHashKey>
+{
+  typedef nsTHashtable<::detail::VoidPtrHashKey> Base;
+  typedef nsPtrHashKey<T> EntryType;
+
+  // We play games with reinterpret_cast'ing between these two classes, so
+  // try to ensure that playing said games is reasonable.
+  static_assert(sizeof(nsPtrHashKey<T>) == sizeof(::detail::VoidPtrHashKey),
+                "hash keys must be the same size");
+
+  nsTHashtable(const nsTHashtable& aOther) = delete;
+  nsTHashtable& operator=(const nsTHashtable& aOther) = delete;
+
+public:
+  nsTHashtable() = default;
+  explicit nsTHashtable(uint32_t aInitLength)
+    : Base(aInitLength)
+  {}
+
+  ~nsTHashtable() = default;
+
+  nsTHashtable(nsTHashtable&&) = default;
+
+  /* Wrapper functions */
+  using Base::GetGeneration;
+  using Base::Count;
+  using Base::IsEmpty;
+  using Base::Clear;
+
+  using Base::ShallowSizeOfExcludingThis;
+  using Base::ShallowSizeOfIncludingThis;
+
+#ifdef DEBUG
+  using Base::MarkImmutable;
+#endif
+
+  EntryType* GetEntry(T* aKey) const
+  {
+    return reinterpret_cast<EntryType*>(Base::GetEntry(aKey));
+  }
+
+  bool Contains(T* aKey) const
+  {
+    return Base::Contains(aKey);
+  }
+
+  EntryType* PutEntry(T* aKey)
+  {
+    return reinterpret_cast<EntryType*>(Base::PutEntry(aKey));
+  }
+
+  MOZ_MUST_USE
+  EntryType* PutEntry(T* aKey, const mozilla::fallible_t&)
+  {
+    return reinterpret_cast<EntryType*>(
+      Base::PutEntry(aKey, mozilla::fallible));
+  }
+
+  void RemoveEntry(T* aKey)
+  {
+    Base::RemoveEntry(aKey);
+  }
+
+  void RemoveEntry(EntryType* aEntry)
+  {
+    Base::RemoveEntry(reinterpret_cast<::detail::VoidPtrHashKey*>(aEntry));
+  }
+
+  void RawRemoveEntry(EntryType* aEntry)
+  {
+    Base::RawRemoveEntry(reinterpret_cast<::detail::VoidPtrHashKey*>(aEntry));
+  }
+
+  class Iterator : public Base::Iterator
+  {
+  public:
+    typedef nsTHashtable::Base::Iterator Base;
+
+    explicit Iterator(nsTHashtable* aTable) : Base(aTable) {}
+    Iterator(Iterator&& aOther) : Base(mozilla::Move(aOther)) {}
+    ~Iterator() = default;
+
+    EntryType* Get() const { return reinterpret_cast<EntryType*>(Base::Get()); }
+
+  private:
+    Iterator() = delete;
+    Iterator(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&) = delete;
+    Iterator& operator=(Iterator&&) = delete;
+  };
+
+  Iterator Iter() { return Iterator(this); }
+
+  Iterator ConstIter() const
+  {
+    return Iterator(const_cast<nsTHashtable*>(this));
+  }
+
+  void SwapElements(nsTHashtable& aOther)
+  {
+    Base::SwapElements(aOther);
+  }
+};
+
+#endif // nsTHashtable_h__
diff --git a/xpcom/glue/nsTObserverArray.cpp b/xpcom/glue/nsTObserverArray.cpp
new file mode 100644
index 0000000000..dd68631f49
--- /dev/null
+++ b/xpcom/glue/nsTObserverArray.cpp
@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTObserverArray.h"
+
+void
+nsTObserverArray_base::AdjustIterators(index_type aModPos,
+                                       diff_type aAdjustment)
+{
+  NS_PRECONDITION(aAdjustment == -1 || aAdjustment == 1, "invalid adjustment");
+  Iterator_base* iter = mIterators;
+  while (iter) {
+    if (iter->mPosition > aModPos) {
+      iter->mPosition += aAdjustment;
+    }
+    iter = iter->mNext;
+  }
+}
+
+void
+nsTObserverArray_base::ClearIterators()
+{
+  Iterator_base* iter = mIterators;
+  while (iter) {
+    iter->mPosition = 0;
+    iter = iter->mNext;
+  }
+}
diff --git a/xpcom/glue/nsTObserverArray.h b/xpcom/glue/nsTObserverArray.h
new file mode 100644
index 0000000000..e9966d0807
--- /dev/null
+++ b/xpcom/glue/nsTObserverArray.h
@@ -0,0 +1,520 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTObserverArray_h___
+#define nsTObserverArray_h___
+
+#include "mozilla/MemoryReporting.h"
+#include "nsTArray.h"
+#include "nsCycleCollectionNoteChild.h"
+
+/**
+ * An array of observers. Like a normal array, but supports iterators that are
+ * stable even if the array is modified during iteration.
+ * The template parameter T is the observer type the array will hold;
+ * N is the number of built-in storage slots that come with the array.
+ * NOTE: You probably want to use nsTObserverArray, unless you specifically
+ * want built-in storage. See below.
+ * @see nsTObserverArray, nsTArray
+ */
+
+class nsTObserverArray_base
+{
+public:
+  typedef size_t index_type;
+  typedef size_t size_type;
+  typedef ptrdiff_t diff_type;
+
+protected:
+  class Iterator_base
+  {
+  protected:
+    friend class nsTObserverArray_base;
+
+    Iterator_base(index_type aPosition, Iterator_base* aNext)
+      : mPosition(aPosition)
+      , mNext(aNext)
+    {
+    }
+
+    // The current position of the iterator. Its exact meaning differs
+    // depending on iterator. See nsTObserverArray<T>::ForwardIterator.
+    index_type mPosition;
+
+    // The next iterator currently iterating the same array
+    Iterator_base* mNext;
+  };
+
+  nsTObserverArray_base() : mIterators(nullptr) {}
+
+  ~nsTObserverArray_base()
+  {
+    NS_ASSERTION(mIterators == nullptr, "iterators outlasting array");
+  }
+
+  /**
+   * Adjusts iterators after an element has been inserted or removed
+   * from the array.
+   * @param aModPos     Position where elements were added or removed.
+   * @param aAdjustment -1 if an element was removed, 1 if an element was
+   *                    added.
+   */
+  void AdjustIterators(index_type aModPos, diff_type aAdjustment);
+
+  /**
+   * Clears iterators when the array is destroyed.
+   */
+  void ClearIterators();
+
+  mutable Iterator_base* mIterators;
+};
+
+template<class T, size_t N>
+class nsAutoTObserverArray : protected nsTObserverArray_base
+{
+public:
+  typedef T           elem_type;
+  typedef nsTArray<T> array_type;
+
+  nsAutoTObserverArray() {}
+
+  //
+  // Accessor methods
+  //
+
+  // @return The number of elements in the array.
+  size_type Length() const { return mArray.Length(); }
+
+  // @return True if the array is empty or false otherwise.
+  bool IsEmpty() const { return mArray.IsEmpty(); }
+
+  // This method provides direct access to an element of the array. The given
+  // index must be within the array bounds. If the underlying array may change
+  // during iteration, use an iterator instead of this function.
+  // @param aIndex The index of an element in the array.
+  // @return A reference to the i'th element of the array.
+  elem_type& ElementAt(index_type aIndex)
+  {
+    return mArray.ElementAt(aIndex);
+  }
+
+  // Same as above, but readonly.
+  const elem_type& ElementAt(index_type aIndex) const
+  {
+    return mArray.ElementAt(aIndex);
+  }
+
+  // This method provides direct access to an element of the array in a bounds
+  // safe manner. If the requested index is out of bounds the provided default
+  // value is returned.
+  // @param aIndex The index of an element in the array.
+  // @param aDef   The value to return if the index is out of bounds.
+  elem_type& SafeElementAt(index_type aIndex, elem_type& aDef)
+  {
+    return mArray.SafeElementAt(aIndex, aDef);
+  }
+
+  // Same as above, but readonly.
+  const elem_type& SafeElementAt(index_type aIndex, const elem_type& aDef) const
+  {
+    return mArray.SafeElementAt(aIndex, aDef);
+  }
+
+  // No operator[] is provided because the point of this class is to support
+  // allow modifying the array during iteration, and ElementAt() is not safe
+  // in those conditions.
+
+  //
+  // Search methods
+  //
+
+  // This method searches, starting from the beginning of the array,
+  // for the first element in this array that is equal to the given element.
+  // 'operator==' must be defined for elem_type.
+  // @param aItem The item to search for.
+  // @return      true if the element was found.
+  template<class Item>
+  bool Contains(const Item& aItem) const
+  {
+    return IndexOf(aItem) != array_type::NoIndex;
+  }
+
+  // This method searches for the offset of the first element in this
+  // array that is equal to the given element.
+  // 'operator==' must be defined for elem_type.
+  // @param aItem  The item to search for.
+  // @param aStart The index to start from.
+  // @return The index of the found element or NoIndex if not found.
+  template<class Item>
+  index_type IndexOf(const Item& aItem, index_type aStart = 0) const
+  {
+    return mArray.IndexOf(aItem, aStart);
+  }
+
+  //
+  // Mutation methods
+  //
+
+  // Insert a given element at the given index.
+  // @param aIndex The index at which to insert item.
+  // @param aItem  The item to insert,
+  // @return A pointer to the newly inserted element, or a null on DOM
+  template<class Item>
+  elem_type* InsertElementAt(index_type aIndex, const Item& aItem)
+  {
+    elem_type* item = mArray.InsertElementAt(aIndex, aItem);
+    AdjustIterators(aIndex, 1);
+    return item;
+  }
+
+  // Same as above but without copy constructing.
+  // This is useful to avoid temporaries.
+  elem_type* InsertElementAt(index_type aIndex)
+  {
+    elem_type* item = mArray.InsertElementAt(aIndex);
+    AdjustIterators(aIndex, 1);
+    return item;
+  }
+
+  // Prepend an element to the array unless it already exists in the array.
+  // 'operator==' must be defined for elem_type.
+  // @param aItem The item to prepend.
+  // @return true if the element was found, or inserted successfully.
+  template<class Item>
+  bool PrependElementUnlessExists(const Item& aItem)
+  {
+    if (Contains(aItem)) {
+      return true;
+    }
+
+    bool inserted = mArray.InsertElementAt(0, aItem) != nullptr;
+    AdjustIterators(0, 1);
+    return inserted;
+  }
+
+  // Append an element to the array.
+  // @param aItem The item to append.
+  // @return A pointer to the newly appended element, or null on OOM.
+  template<class Item>
+  elem_type* AppendElement(const Item& aItem)
+  {
+    return mArray.AppendElement(aItem);
+  }
+
+  // Same as above, but without copy-constructing. This is useful to avoid
+  // temporaries.
+  elem_type* AppendElement()
+  {
+    return mArray.AppendElement();
+  }
+
+  // Append an element to the array unless it already exists in the array.
+  // 'operator==' must be defined for elem_type.
+  // @param aItem The item to append.
+  // @return true if the element was found, or inserted successfully.
+  template<class Item>
+  bool AppendElementUnlessExists(const Item& aItem)
+  {
+    return Contains(aItem) || AppendElement(aItem) != nullptr;
+  }
+
+  // Remove an element from the array.
+  // @param aIndex The index of the item to remove.
+  void RemoveElementAt(index_type aIndex)
+  {
+    NS_ASSERTION(aIndex < mArray.Length(), "invalid index");
+    mArray.RemoveElementAt(aIndex);
+    AdjustIterators(aIndex, -1);
+  }
+
+  // This helper function combines IndexOf with RemoveElementAt to "search
+  // and destroy" the first element that is equal to the given element.
+  // 'operator==' must be defined for elem_type.
+  // @param aItem The item to search for.
+  // @return true if the element was found and removed.
+  template<class Item>
+  bool RemoveElement(const Item& aItem)
+  {
+    index_type index = mArray.IndexOf(aItem, 0);
+    if (index == array_type::NoIndex) {
+      return false;
+    }
+
+    mArray.RemoveElementAt(index);
+    AdjustIterators(index, -1);
+    return true;
+  }
+
+  // See nsTArray::RemoveElementsBy.
+  void RemoveElementsBy(mozilla::function<bool(const elem_type&)> aPredicate)
+  {
+    index_type i = 0;
+    mArray.RemoveElementsBy([&](const elem_type& aItem) {
+      if (aPredicate(aItem)) {
+        // This element is going to be removed.
+        AdjustIterators(i, -1);
+        return true;
+      }
+      ++i;
+      return false;
+    });
+  }
+
+  // Removes all observers and collapses all iterators to the beginning of
+  // the array. The result is that forward iterators will see all elements
+  // in the array.
+  void Clear()
+  {
+    mArray.Clear();
+    ClearIterators();
+  }
+
+  // Compact the array to minimize the memory it uses
+  void Compact() { mArray.Compact(); }
+
+  // Returns the number of bytes on the heap taken up by this object, not
+  // including sizeof(*this). If you want to measure anything hanging off the
+  // array, you must iterate over the elements and measure them individually;
+  // hence the "Shallow" prefix.
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return mArray.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  //
+  // Iterators
+  //
+
+  // Base class for iterators. Do not use this directly.
+  class Iterator : public Iterator_base
+  {
+  protected:
+    friend class nsAutoTObserverArray;
+    typedef nsAutoTObserverArray<T, N> array_type;
+
+    Iterator(index_type aPosition, const array_type& aArray)
+      : Iterator_base(aPosition, aArray.mIterators)
+      , mArray(const_cast<array_type&>(aArray))
+    {
+      aArray.mIterators = this;
+    }
+
+    ~Iterator()
+    {
+      NS_ASSERTION(mArray.mIterators == this,
+                   "Iterators must currently be destroyed in opposite order "
+                   "from the construction order. It is suggested that you "
+                   "simply put them on the stack");
+      mArray.mIterators = mNext;
+    }
+
+    // The array we're iterating
+    array_type& mArray;
+  };
+
+  // Iterates the array forward from beginning to end. mPosition points
+  // to the element that will be returned on next call to GetNext.
+  // Elements:
+  // - prepended to the array during iteration *will not* be traversed
+  // - appended during iteration *will* be traversed
+  // - removed during iteration *will not* be traversed.
+  // @see EndLimitedIterator
+  class ForwardIterator : protected Iterator
+  {
+  public:
+    typedef nsAutoTObserverArray<T, N> array_type;
+    typedef Iterator                   base_type;
+
+    explicit ForwardIterator(const array_type& aArray)
+      : Iterator(0, aArray)
+    {
+    }
+
+    ForwardIterator(const array_type& aArray, index_type aPos)
+      : Iterator(aPos, aArray)
+    {
+    }
+
+    bool operator<(const ForwardIterator& aOther) const
+    {
+      NS_ASSERTION(&this->mArray == &aOther.mArray,
+                   "not iterating the same array");
+      return base_type::mPosition < aOther.mPosition;
+    }
+
+    // Returns true if there are more elements to iterate.
+    // This must precede a call to GetNext(). If false is
+    // returned, GetNext() must not be called.
+    bool HasMore() const
+    {
+      return base_type::mPosition < base_type::mArray.Length();
+    }
+
+    // Returns the next element and steps one step. This must
+    // be preceded by a call to HasMore().
+    // @return The next observer.
+    elem_type& GetNext()
+    {
+      NS_ASSERTION(HasMore(), "iterating beyond end of array");
+      return base_type::mArray.ElementAt(base_type::mPosition++);
+    }
+  };
+
+  // EndLimitedIterator works like ForwardIterator, but will not iterate new
+  // observers appended to the array after the iterator was created.
+  class EndLimitedIterator : protected ForwardIterator
+  {
+  public:
+    typedef nsAutoTObserverArray<T, N> array_type;
+    typedef Iterator                   base_type;
+
+    explicit EndLimitedIterator(const array_type& aArray)
+      : ForwardIterator(aArray)
+      , mEnd(aArray, aArray.Length())
+    {
+    }
+
+    // Returns true if there are more elements to iterate.
+    // This must precede a call to GetNext(). If false is
+    // returned, GetNext() must not be called.
+    bool HasMore() const { return *this < mEnd; }
+
+    // Returns the next element and steps one step. This must
+    // be preceded by a call to HasMore().
+    // @return The next observer.
+    elem_type& GetNext()
+    {
+      NS_ASSERTION(HasMore(), "iterating beyond end of array");
+      return base_type::mArray.ElementAt(base_type::mPosition++);
+    }
+
+  private:
+    ForwardIterator mEnd;
+  };
+
+  // Iterates the array backward from end to start. mPosition points
+  // to the element that was returned last.
+  // Elements:
+  // - prepended to the array during iteration *will* be traversed,
+  //   unless the iteration already arrived at the first element
+  // - appended during iteration *will not* be traversed
+  // - removed during iteration *will not* be traversed.
+  class BackwardIterator : protected Iterator
+  {
+  public:
+    typedef nsAutoTObserverArray<T, N> array_type;
+    typedef Iterator                   base_type;
+
+    explicit BackwardIterator(const array_type& aArray)
+      : Iterator(aArray.Length(), aArray)
+    {
+    }
+
+    // Returns true if there are more elements to iterate.
+    // This must precede a call to GetNext(). If false is
+    // returned, GetNext() must not be called.
+    bool HasMore() const { return base_type::mPosition > 0; }
+
+    // Returns the next element and steps one step. This must
+    // be preceded by a call to HasMore().
+    // @return The next observer.
+    elem_type& GetNext()
+    {
+      NS_ASSERTION(HasMore(), "iterating beyond start of array");
+      return base_type::mArray.ElementAt(--base_type::mPosition);
+    }
+
+    // Removes the element at the current iterator position.
+    // (the last element returned from |GetNext()|)
+    // This will not affect the next call to |GetNext()|
+    void Remove()
+    {
+      return base_type::mArray.RemoveElementAt(base_type::mPosition);
+    }
+  };
+
+protected:
+  AutoTArray<T, N> mArray;
+};
+
+template<class T>
+class nsTObserverArray : public nsAutoTObserverArray<T, 0>
+{
+public:
+  typedef nsAutoTObserverArray<T, 0>       base_type;
+  typedef nsTObserverArray_base::size_type size_type;
+
+  //
+  // Initialization methods
+  //
+
+  nsTObserverArray() {}
+
+  // Initialize this array and pre-allocate some number of elements.
+  explicit nsTObserverArray(size_type aCapacity)
+  {
+    base_type::mArray.SetCapacity(aCapacity);
+  }
+};
+
+template<typename T, size_t N>
+inline void
+ImplCycleCollectionUnlink(nsAutoTObserverArray<T, N>& aField)
+{
+  aField.Clear();
+}
+
+template<typename T, size_t N>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsAutoTObserverArray<T, N>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  aFlags |= CycleCollectionEdgeNameArrayFlag;
+  size_t length = aField.Length();
+  for (size_t i = 0; i < length; ++i) {
+    ImplCycleCollectionTraverse(aCallback, aField.ElementAt(i), aName, aFlags);
+  }
+}
+
+// XXXbz I wish I didn't have to pass in the observer type, but I
+// don't see a way to get it out of array_.
+// Note that this macro only works if the array holds pointers to XPCOM objects.
+#define NS_OBSERVER_ARRAY_NOTIFY_XPCOM_OBSERVERS(array_, obstype_, func_, params_) \
+  PR_BEGIN_MACRO                                                             \
+    nsTObserverArray<obstype_ *>::ForwardIterator iter_(array_);             \
+    RefPtr<obstype_> obs_;                                                 \
+    while (iter_.HasMore()) {                                                 \
+      obs_ = iter_.GetNext();                                                \
+      obs_ -> func_ params_ ;                                                \
+    }                                                                        \
+  PR_END_MACRO
+
+// Note that this macro only works if the array holds pointers to XPCOM objects.
+#define NS_OBSERVER_ARRAY_NOTIFY_OBSERVERS(array_, obstype_, func_, params_) \
+  PR_BEGIN_MACRO                                                             \
+    nsTObserverArray<obstype_ *>::ForwardIterator iter_(array_);             \
+    obstype_* obs_;                                                          \
+    while (iter_.HasMore()) {                                                \
+      obs_ = iter_.GetNext();                                                \
+      obs_ -> func_ params_ ;                                                \
+    }                                                                        \
+  PR_END_MACRO
+
+#define NS_OBSERVER_ARRAY_NOTIFY_OBSERVERS_WITH_QI(array_, basetype_, obstype_, func_, params_) \
+  PR_BEGIN_MACRO                                                             \
+    nsTObserverArray<basetype_ *>::ForwardIterator iter_(array_);            \
+    basetype_* obsbase_;                                                     \
+    while (iter_.HasMore()) {                                                \
+      obsbase_ = iter_.GetNext();                                            \
+      nsCOMPtr<obstype_> obs_ = do_QueryInterface(obsbase_);                 \
+      if (obs_) {                                                            \
+        obs_ -> func_ params_ ;                                              \
+      }                                                                      \
+    }                                                                        \
+  PR_END_MACRO
+#endif // nsTObserverArray_h___
diff --git a/xpcom/glue/nsTPriorityQueue.h b/xpcom/glue/nsTPriorityQueue.h
new file mode 100644
index 0000000000..20a0fc8a55
--- /dev/null
+++ b/xpcom/glue/nsTPriorityQueue.h
@@ -0,0 +1,161 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NS_TPRIORITY_QUEUE_H_
+#define NS_TPRIORITY_QUEUE_H_
+
+#include "nsTArray.h"
+#include "nsDebug.h"
+
+/**
+ * A templatized priority queue data structure that uses an nsTArray to serve as
+ * a binary heap. The default comparator causes this to act like a min-heap.
+ * Only the LessThan method of the comparator is used.
+ */
+template<class T, class Compare = nsDefaultComparator<T, T>>
+class nsTPriorityQueue
+{
+public:
+  typedef typename nsTArray<T>::size_type size_type;
+
+  /**
+   * Default constructor also creates a comparator object using the default
+   * constructor for type Compare.
+   */
+  nsTPriorityQueue() : mCompare(Compare()) {}
+
+  /**
+   * Constructor to allow a specific instance of a comparator object to be
+   * used.
+   */
+  explicit nsTPriorityQueue(const Compare& aComp) : mCompare(aComp) {}
+
+  /**
+   * Copy constructor
+   */
+  nsTPriorityQueue(const nsTPriorityQueue& aOther)
+    : mElements(aOther.mElements)
+    , mCompare(aOther.mCompare)
+  {
+  }
+
+  /**
+   * @return True if the queue is empty or false otherwise.
+   */
+  bool IsEmpty() const { return mElements.IsEmpty(); }
+
+  /**
+   * @return The number of elements in the queue.
+   */
+  size_type Length() const { return mElements.Length(); }
+
+  /**
+   * @return The topmost element in the queue without changing the queue. This
+   * is the element 'a' such that there is no other element 'b' in the queue for
+   * which Compare(b, a) returns true. (Since this container does not check
+   * for duplicate entries there may exist 'b' for which Compare(a, b) returns
+   * false.)
+   */
+  const T& Top() const
+  {
+    MOZ_ASSERT(!mElements.IsEmpty(), "Empty queue");
+    return mElements[0];
+  }
+
+  /**
+   * Adds an element to the queue
+   * @param aElement The element to add
+   * @return true on success, false on out of memory.
+   */
+  bool Push(const T& aElement)
+  {
+    T* elem = mElements.AppendElement(aElement);
+    if (!elem) {
+      return false;  // Out of memory
+    }
+
+    // Sift up
+    size_type i = mElements.Length() - 1;
+    while (i) {
+      size_type parent = (size_type)((i - 1) / 2);
+      if (mCompare.LessThan(mElements[parent], mElements[i])) {
+        break;
+      }
+      Swap(i, parent);
+      i = parent;
+    }
+
+    return true;
+  }
+
+  /**
+   * Removes and returns the top-most element from the queue.
+   * @return The topmost element, that is, the element 'a' such that there is no
+   * other element 'b' in the queue for which Compare(b, a) returns true.
+   * @see Top()
+   */
+  T Pop()
+  {
+    MOZ_ASSERT(!mElements.IsEmpty(), "Empty queue");
+    T pop = mElements[0];
+
+    // Move last to front
+    mElements[0] = mElements[mElements.Length() - 1];
+    mElements.TruncateLength(mElements.Length() - 1);
+
+    // Sift down
+    size_type i = 0;
+    while (2 * i + 1 < mElements.Length()) {
+      size_type swap = i;
+      size_type l_child = 2 * i + 1;
+      if (mCompare.LessThan(mElements[l_child], mElements[i])) {
+        swap = l_child;
+      }
+      size_type r_child = l_child + 1;
+      if (r_child < mElements.Length() &&
+          mCompare.LessThan(mElements[r_child], mElements[swap])) {
+        swap = r_child;
+      }
+      if (swap == i) {
+        break;
+      }
+      Swap(i, swap);
+      i = swap;
+    }
+
+    return pop;
+  }
+
+  /**
+   * Removes all elements from the queue.
+   */
+  void Clear() { mElements.Clear(); }
+
+  /**
+   * Provides readonly access to the queue elements as an array. Generally this
+   * should be avoided but may be needed in some situations such as when the
+   * elements contained in the queue need to be enumerated for cycle-collection.
+   * @return A pointer to the first element of the array.  If the array is
+   * empty, then this pointer must not be dereferenced.
+   */
+  const T* Elements() const { return mElements.Elements(); }
+
+protected:
+  /**
+   * Swaps the elements at the specified indices.
+   */
+  void Swap(size_type aIndexA, size_type aIndexB)
+  {
+    T temp = mElements[aIndexA];
+    mElements[aIndexA] = mElements[aIndexB];
+    mElements[aIndexB] = temp;
+  }
+
+  nsTArray<T> mElements;
+  Compare mCompare; // Comparator object
+};
+
+#endif // NS_TPRIORITY_QUEUE_H_
diff --git a/xpcom/glue/nsTWeakRef.h b/xpcom/glue/nsTWeakRef.h
new file mode 100644
index 0000000000..6c9a5e8ebf
--- /dev/null
+++ b/xpcom/glue/nsTWeakRef.h
@@ -0,0 +1,176 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTWeakRef_h__
+#define nsTWeakRef_h__
+
+#ifndef nsDebug_h___
+#include "nsDebug.h"
+#endif
+
+/**
+ * A weak reference class for use with generic C++ objects.  NOT THREADSAFE!
+ *
+ * Example usage:
+ *
+ *   class A {
+ *   public:
+ *     A() : mWeakSelf(this) {
+ *     }
+ *     ~A() {
+ *       mWeakSelf.forget();
+ *     }
+ *     void Bar() { printf("Bar!\n"); }
+ *     const nsTWeakRef<A> &AsWeakRef() const { return mWeakSelf; }
+ *   private:
+ *     nsTWeakRef<A> mWeakSelf;
+ *   };
+ *
+ *   class B {
+ *   public:
+ *     void SetA(const nsTWeakRef<A> &a) {
+ *       mA = a;
+ *     }
+ *     void Foo() {
+ *       if (mA)
+ *         mA->Bar();
+ *     }
+ *   private:
+ *     nsTWeakRef<A> mA;
+ *   };
+ *
+ *   void Test() {
+ *     B b;
+ *     {
+ *       A a;
+ *       b.SetA(a.AsWeakRef());
+ *       b.Foo();  // prints "Bar!"
+ *     }
+ *     b.Foo();  // prints nothing because |a| has already been destroyed
+ *   }
+ *
+ * One can imagine much more complex examples, especially when asynchronous
+ * event processing is involved.
+ *
+ * Keep in mind that you should only ever need a class like this when you have
+ * multiple instances of B, such that it is not possible for A and B to simply
+ * have pointers to one another.
+ */
+template<class Type>
+class nsTWeakRef
+{
+public:
+  ~nsTWeakRef()
+  {}
+
+  /**
+   * Construct from an object pointer (may be null).
+   */
+  explicit nsTWeakRef(Type* aObj = nullptr)
+  {
+    if (aObj) {
+      mRef = new Inner(aObj);
+    } else {
+      mRef = nullptr;
+    }
+  }
+
+  /**
+   * Construct from another weak reference object.
+   */
+  explicit nsTWeakRef(const nsTWeakRef<Type>& aOther) : mRef(aOther.mRef)
+  {}
+
+  /**
+   * Assign from an object pointer.
+   */
+  nsTWeakRef<Type>& operator=(Type* aObj)
+  {
+    if (aObj) {
+      mRef = new Inner(aObj);
+    } else {
+      mRef = nullptr;
+    }
+    return *this;
+  }
+
+  /**
+   * Assign from another weak reference object.
+   */
+  nsTWeakRef<Type>& operator=(const nsTWeakRef<Type>& aOther)
+  {
+    mRef = aOther.mRef;
+    return *this;
+  }
+
+  /**
+   * Get the referenced object.  This method may return null if the reference
+   * has been cleared or if an out-of-memory error occurred at assignment.
+   */
+  Type* get() const { return mRef ? mRef->mObj : nullptr; }
+
+  /**
+   * Called to "null out" the weak reference.  Typically, the object referenced
+   * by this weak reference calls this method when it is being destroyed.
+   * @returns The former referenced object.
+   */
+  Type* forget()
+  {
+    Type* obj;
+    if (mRef) {
+      obj = mRef->mObj;
+      mRef->mObj = nullptr;
+      mRef = nullptr;
+    } else {
+      obj = nullptr;
+    }
+    return obj;
+  }
+
+  /**
+   * Allow |*this| to be treated as a |Type*| for convenience.
+   */
+  operator Type*() const { return get(); }
+
+  /**
+   * Allow |*this| to be treated as a |Type*| for convenience.  Use with
+   * caution since this method will crash if the referenced object is null.
+   */
+  Type* operator->() const MOZ_NO_ADDREF_RELEASE_ON_RETURN
+  {
+    NS_ASSERTION(mRef && mRef->mObj,
+                 "You can't dereference a null weak reference with operator->().");
+    return get();
+  }
+
+private:
+
+  struct Inner
+  {
+    int     mCnt;
+    Type*   mObj;
+
+    explicit Inner(Type* aObj)
+      : mCnt(1)
+      , mObj(aObj)
+    {
+    }
+    void AddRef()
+    {
+      ++mCnt;
+    }
+    void Release()
+    {
+      if (--mCnt == 0) {
+        delete this;
+      }
+    }
+  };
+
+  RefPtr<Inner> mRef;
+};
+
+#endif  // nsTWeakRef_h__
diff --git a/xpcom/glue/nsTextFormatter.cpp b/xpcom/glue/nsTextFormatter.cpp
new file mode 100644
index 0000000000..ab9941d156
--- /dev/null
+++ b/xpcom/glue/nsTextFormatter.cpp
@@ -0,0 +1,1394 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Portable safe sprintf code.
+ *
+ * Code based on mozilla/nsprpub/src/io/prprf.c rev 3.7
+ *
+ * Contributor(s):
+ *   Kipp E.B. Hickman  <kipp@netscape.com>  (original author)
+ *   Frank Yung-Fong Tang  <ftang@netscape.com>
+ *   Daniele Nicolodi  <daniele@grinta.net>
+ */
+
+/*
+ * Copied from xpcom/ds/nsTextFormatter.cpp r1.22
+ *     Changed to use nsMemory and Frozen linkage
+ *                  -- Prasad <prasad@medhas.org>
+ */
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include "prdtoa.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Sprintf.h"
+#include "prmem.h"
+#include "nsCRTGlue.h"
+#include "nsTextFormatter.h"
+#include "nsMemory.h"
+
+/*
+** Note: on some platforms va_list is defined as an array,
+** and requires array notation.
+*/
+
+#ifdef HAVE_VA_COPY
+#define VARARGS_ASSIGN(foo, bar)        VA_COPY(foo,bar)
+#elif defined(HAVE_VA_LIST_AS_ARRAY)
+#define VARARGS_ASSIGN(foo, bar)	foo[0] = bar[0]
+#else
+#define VARARGS_ASSIGN(foo, bar)	(foo) = (bar)
+#endif
+
+typedef struct SprintfStateStr SprintfState;
+
+struct SprintfStateStr
+{
+  int (*stuff)(SprintfState* aState, const char16_t* aStr, uint32_t aLen);
+
+  char16_t* base;
+  char16_t* cur;
+  uint32_t maxlen;
+
+  void* stuffclosure;
+};
+
+/*
+** Numbered Arguement State
+*/
+struct NumArgState
+{
+  int type;    /* type of the current ap */
+  va_list ap;  /* point to the corresponding position on ap */
+
+  enum Type
+  {
+    INT16,
+    UINT16,
+    INTN,
+    UINTN,
+    INT32,
+    UINT32,
+    INT64,
+    UINT64,
+    STRING,
+    DOUBLE,
+    INTSTR,
+    UNISTRING,
+    UNKNOWN
+  };
+};
+
+#define NAS_DEFAULT_NUM 20  /* default number of NumberedArgumentState array */
+
+#define _LEFT		0x1
+#define _SIGNED		0x2
+#define _SPACED		0x4
+#define _ZEROS		0x8
+#define _NEG		0x10
+
+#define ELEMENTS_OF(array_) (sizeof(array_) / sizeof(array_[0]))
+
+#define PR_CHECK_DELETE(nas) if (nas && (nas != nasArray)) { PR_DELETE(nas); }
+
+/*
+** Fill into the buffer using the data in src
+*/
+static int
+fill2(SprintfState* aState, const char16_t* aSrc, int aSrcLen, int aWidth,
+      int aFlags)
+{
+  char16_t space = ' ';
+  int rv;
+
+  aWidth -= aSrcLen;
+  /* Right adjusting */
+  if ((aWidth > 0) && ((aFlags & _LEFT) == 0)) {
+    if (aFlags & _ZEROS) {
+      space = '0';
+    }
+    while (--aWidth >= 0) {
+      rv = (*aState->stuff)(aState, &space, 1);
+      if (rv < 0) {
+        return rv;
+      }
+    }
+  }
+
+  /* Copy out the source data */
+  rv = (*aState->stuff)(aState, aSrc, aSrcLen);
+  if (rv < 0) {
+    return rv;
+  }
+
+  /* Left adjusting */
+  if ((aWidth > 0) && ((aFlags & _LEFT) != 0)) {
+    while (--aWidth >= 0) {
+      rv = (*aState->stuff)(aState, &space, 1);
+      if (rv < 0) {
+        return rv;
+      }
+    }
+  }
+  return 0;
+}
+
+/*
+** Fill a number. The order is: optional-sign zero-filling conversion-digits
+*/
+static int
+fill_n(SprintfState* aState, const char16_t* aSrc, int aSrcLen, int aWidth,
+       int aPrec, int aType, int aFlags)
+{
+  int zerowidth   = 0;
+  int precwidth   = 0;
+  int signwidth   = 0;
+  int leftspaces  = 0;
+  int rightspaces = 0;
+  int cvtwidth;
+  int rv;
+  char16_t sign;
+  char16_t space = ' ';
+  char16_t zero = '0';
+
+  if ((aType & 1) == 0) {
+    if (aFlags & _NEG) {
+      sign = '-';
+      signwidth = 1;
+    } else if (aFlags & _SIGNED) {
+      sign = '+';
+      signwidth = 1;
+    } else if (aFlags & _SPACED) {
+      sign = ' ';
+      signwidth = 1;
+    }
+  }
+  cvtwidth = signwidth + aSrcLen;
+
+  if (aPrec > 0) {
+    if (aPrec > aSrcLen) {
+      /* Need zero filling */
+      precwidth = aPrec - aSrcLen;
+      cvtwidth += precwidth;
+    }
+  }
+
+  if ((aFlags & _ZEROS) && (aPrec < 0)) {
+    if (aWidth > cvtwidth) {
+      /* Zero filling */
+      zerowidth = aWidth - cvtwidth;
+      cvtwidth += zerowidth;
+    }
+  }
+
+  if (aFlags & _LEFT) {
+    if (aWidth > cvtwidth) {
+      /* Space filling on the right (i.e. left adjusting) */
+      rightspaces = aWidth - cvtwidth;
+    }
+  } else {
+    if (aWidth > cvtwidth) {
+      /* Space filling on the left (i.e. right adjusting) */
+      leftspaces = aWidth - cvtwidth;
+    }
+  }
+  while (--leftspaces >= 0) {
+    rv = (*aState->stuff)(aState, &space, 1);
+    if (rv < 0) {
+      return rv;
+    }
+  }
+  if (signwidth) {
+    rv = (*aState->stuff)(aState, &sign, 1);
+    if (rv < 0) {
+      return rv;
+    }
+  }
+  while (--precwidth >= 0) {
+    rv = (*aState->stuff)(aState,  &space, 1);
+    if (rv < 0) {
+      return rv;
+    }
+  }
+  while (--zerowidth >= 0) {
+    rv = (*aState->stuff)(aState,  &zero, 1);
+    if (rv < 0) {
+      return rv;
+    }
+  }
+  rv = (*aState->stuff)(aState, aSrc, aSrcLen);
+  if (rv < 0) {
+    return rv;
+  }
+  while (--rightspaces >= 0) {
+    rv = (*aState->stuff)(aState,  &space, 1);
+    if (rv < 0) {
+      return rv;
+    }
+  }
+  return 0;
+}
+
+/*
+** Convert a long into its printable form
+*/
+static int
+cvt_l(SprintfState* aState, long aNum, int aWidth, int aPrec, int aRadix,
+      int aType, int aFlags, const char16_t* aHexStr)
+{
+  char16_t cvtbuf[100];
+  char16_t* cvt;
+  int digits;
+
+  /* according to the man page this needs to happen */
+  if ((aPrec == 0) && (aNum == 0)) {
+    return 0;
+  }
+
+  /*
+  ** Converting decimal is a little tricky. In the unsigned case we
+  ** need to stop when we hit 10 digits. In the signed case, we can
+  ** stop when the number is zero.
+  */
+  cvt = &cvtbuf[0] + ELEMENTS_OF(cvtbuf);
+  digits = 0;
+  while (aNum) {
+    int digit = (((unsigned long)aNum) % aRadix) & 0xF;
+    *--cvt = aHexStr[digit];
+    digits++;
+    aNum = (long)(((unsigned long)aNum) / aRadix);
+  }
+  if (digits == 0) {
+    *--cvt = '0';
+    digits++;
+  }
+
+  /*
+  ** Now that we have the number converted without its sign, deal with
+  ** the sign and zero padding.
+  */
+  return fill_n(aState, cvt, digits, aWidth, aPrec, aType, aFlags);
+}
+
+/*
+** Convert a 64-bit integer into its printable form
+*/
+static int
+cvt_ll(SprintfState* aState, int64_t aNum, int aWidth, int aPrec, int aRadix,
+       int aType, int aFlags, const char16_t* aHexStr)
+{
+  char16_t cvtbuf[100];
+  char16_t* cvt;
+  int digits;
+  int64_t rad;
+
+  /* according to the man page this needs to happen */
+  if (aPrec == 0 && aNum == 0) {
+    return 0;
+  }
+
+  /*
+  ** Converting decimal is a little tricky. In the unsigned case we
+  ** need to stop when we hit 10 digits. In the signed case, we can
+  ** stop when the number is zero.
+  */
+  rad = aRadix;
+  cvt = &cvtbuf[0] + ELEMENTS_OF(cvtbuf);
+  digits = 0;
+  while (aNum != 0) {
+    *--cvt = aHexStr[int32_t(aNum % rad) & 0xf];
+    digits++;
+    aNum /= rad;
+  }
+  if (digits == 0) {
+    *--cvt = '0';
+    digits++;
+  }
+
+  /*
+  ** Now that we have the number converted without its sign, deal with
+  ** the sign and zero padding.
+  */
+  return fill_n(aState, cvt, digits, aWidth, aPrec, aType, aFlags);
+}
+
+/*
+** Convert a double precision floating point number into its printable
+** form.
+*/
+static int
+cvt_f(SprintfState* aState, double aDouble, int aWidth, int aPrec,
+      const char16_t aType, int aFlags)
+{
+  int    mode = 2;
+  int    decpt;
+  int    sign;
+  char   buf[256];
+  char*  bufp = buf;
+  int    bufsz = 256;
+  char   num[256];
+  char*  nump;
+  char*  endnum;
+  int    numdigits = 0;
+  char   exp = 'e';
+
+  if (aPrec == -1) {
+    aPrec = 6;
+  } else if (aPrec > 50) {
+    // limit precision to avoid PR_dtoa bug 108335
+    // and to prevent buffers overflows
+    aPrec = 50;
+  }
+
+  switch (aType) {
+    case 'f':
+      numdigits = aPrec;
+      mode = 3;
+      break;
+    case 'E':
+      exp = 'E';
+      MOZ_FALLTHROUGH;
+    case 'e':
+      numdigits = aPrec + 1;
+      mode = 2;
+      break;
+    case 'G':
+      exp = 'E';
+      MOZ_FALLTHROUGH;
+    case 'g':
+      if (aPrec == 0) {
+        aPrec = 1;
+      }
+      numdigits = aPrec;
+      mode = 2;
+      break;
+    default:
+      NS_ERROR("invalid aType passed to cvt_f");
+  }
+
+  if (PR_dtoa(aDouble, mode, numdigits, &decpt, &sign,
+              &endnum, num, bufsz) == PR_FAILURE) {
+    buf[0] = '\0';
+    return -1;
+  }
+  numdigits = endnum - num;
+  nump = num;
+
+  if (sign) {
+    *bufp++ = '-';
+  } else if (aFlags & _SIGNED) {
+    *bufp++ = '+';
+  }
+
+  if (decpt == 9999) {
+    while ((*bufp++ = *nump++)) {
+    }
+  } else {
+
+    switch (aType) {
+
+      case 'E':
+      case 'e':
+
+        *bufp++ = *nump++;
+        if (aPrec > 0) {
+          *bufp++ = '.';
+          while (*nump) {
+            *bufp++ = *nump++;
+            aPrec--;
+          }
+          while (aPrec-- > 0) {
+            *bufp++ = '0';
+          }
+        }
+        *bufp++ = exp;
+
+        snprintf(bufp, bufsz - (bufp - buf), "%+03d", decpt - 1);
+        break;
+
+      case 'f':
+
+        if (decpt < 1) {
+          *bufp++ = '0';
+          if (aPrec > 0) {
+            *bufp++ = '.';
+            while (decpt++ && aPrec-- > 0) {
+              *bufp++ = '0';
+            }
+            while (*nump && aPrec-- > 0) {
+              *bufp++ = *nump++;
+            }
+            while (aPrec-- > 0) {
+              *bufp++ = '0';
+            }
+          }
+        } else {
+          while (*nump && decpt-- > 0) {
+            *bufp++ = *nump++;
+          }
+          while (decpt-- > 0) {
+            *bufp++ = '0';
+          }
+          if (aPrec > 0) {
+            *bufp++ = '.';
+            while (*nump && aPrec-- > 0) {
+              *bufp++ = *nump++;
+            }
+            while (aPrec-- > 0) {
+              *bufp++ = '0';
+            }
+          }
+        }
+        *bufp = '\0';
+        break;
+
+      case 'G':
+      case 'g':
+
+        if ((decpt < -3) || ((decpt - 1) >= aPrec)) {
+          *bufp++ = *nump++;
+          numdigits--;
+          if (numdigits > 0) {
+            *bufp++ = '.';
+            while (*nump) {
+              *bufp++ = *nump++;
+            }
+          }
+          *bufp++ = exp;
+          snprintf(bufp, bufsz - (bufp - buf), "%+03d", decpt - 1);
+        } else {
+          if (decpt < 1) {
+            *bufp++ = '0';
+            if (aPrec > 0) {
+              *bufp++ = '.';
+              while (decpt++) {
+                *bufp++ = '0';
+              }
+              while (*nump) {
+                *bufp++ = *nump++;
+              }
+            }
+          } else {
+            while (*nump && decpt-- > 0) {
+              *bufp++ = *nump++;
+              numdigits--;
+            }
+            while (decpt-- > 0) {
+              *bufp++ = '0';
+            }
+            if (numdigits > 0) {
+              *bufp++ = '.';
+              while (*nump) {
+                *bufp++ = *nump++;
+              }
+            }
+          }
+          *bufp = '\0';
+        }
+    }
+  }
+
+  char16_t rbuf[256];
+  char16_t* rbufp = rbuf;
+  bufp = buf;
+  // cast to char16_t
+  while ((*rbufp++ = *bufp++)) {
+  }
+  *rbufp = '\0';
+
+  return fill2(aState, rbuf, NS_strlen(rbuf), aWidth, aFlags);
+}
+
+/*
+** Convert a string into its printable form. |aWidth| is the output
+** width. |aPrec| is the maximum number of characters of |aStr| to output,
+** where -1 means until NUL.
+*/
+static int
+cvt_S(SprintfState* aState, const char16_t* aStr, int aWidth, int aPrec,
+      int aFlags)
+{
+  int slen;
+
+  if (aPrec == 0) {
+    return 0;
+  }
+
+  /* Limit string length by precision value */
+  slen = aStr ? NS_strlen(aStr) : 6;
+  if (aPrec > 0) {
+    if (aPrec < slen) {
+      slen = aPrec;
+    }
+  }
+
+  /* and away we go */
+  return fill2(aState, aStr ? aStr : u"(null)", slen, aWidth, aFlags);
+}
+
+/*
+** Convert a string into its printable form.  |aWidth| is the output
+** width. |aPrec| is the maximum number of characters of |aStr| to output,
+** where -1 means until NUL.
+*/
+static int
+cvt_s(SprintfState* aState, const char* aStr, int aWidth, int aPrec, int aFlags)
+{
+  NS_ConvertUTF8toUTF16 utf16Val(aStr);
+  return cvt_S(aState, utf16Val.get(), aWidth, aPrec, aFlags);
+}
+
+/*
+** BuildArgArray stands for Numbered Argument list Sprintf
+** for example,
+**	fmp = "%4$i, %2$d, %3s, %1d";
+** the number must start from 1, and no gap among them
+*/
+
+static struct NumArgState*
+BuildArgArray(const char16_t* aFmt, va_list aAp, int* aRv,
+              struct NumArgState* aNasArray)
+{
+  int number = 0, cn = 0, i;
+  const char16_t* p;
+  char16_t  c;
+  struct NumArgState* nas;
+
+  /*
+  **	first pass:
+  **	detemine how many legal % I have got, then allocate space
+  */
+  p = aFmt;
+  *aRv = 0;
+  i = 0;
+  while ((c = *p++) != 0) {
+    if (c != '%') {
+      continue;
+    }
+    /* skip %% case */
+    if ((c = *p++) == '%') {
+      continue;
+    }
+
+    while (c != 0) {
+      if (c > '9' || c < '0') {
+        /* numbered argument csae */
+        if (c == '$') {
+          if (i > 0) {
+            *aRv = -1;
+            return nullptr;
+          }
+          number++;
+          break;
+
+        } else {
+          /* non-numbered argument case */
+          if (number > 0) {
+            *aRv = -1;
+            return nullptr;
+          }
+          i = 1;
+          break;
+        }
+      }
+      c = *p++;
+    }
+  }
+
+  if (number == 0) {
+    return nullptr;
+  }
+
+  if (number > NAS_DEFAULT_NUM) {
+    nas = (struct NumArgState*)moz_xmalloc(number * sizeof(struct NumArgState));
+    if (!nas) {
+      *aRv = -1;
+      return nullptr;
+    }
+  } else {
+    nas = aNasArray;
+  }
+
+  for (i = 0; i < number; i++) {
+    nas[i].type = NumArgState::UNKNOWN;
+  }
+
+  /*
+  ** second pass:
+  ** set nas[].type
+  */
+  p = aFmt;
+  while ((c = *p++) != 0) {
+    if (c != '%') {
+      continue;
+    }
+    c = *p++;
+    if (c == '%') {
+      continue;
+    }
+    cn = 0;
+    /* should improve error check later */
+    while (c && c != '$') {
+      cn = cn * 10 + c - '0';
+      c = *p++;
+    }
+
+    if (!c || cn < 1 || cn > number) {
+      *aRv = -1;
+      break;
+    }
+
+    /* nas[cn] starts from 0, and make sure
+             nas[cn].type is not assigned */
+    cn--;
+    if (nas[cn].type != NumArgState::UNKNOWN) {
+      continue;
+    }
+
+    c = *p++;
+
+    /* width */
+    if (c == '*') {
+      /* not supported feature, for the argument is not numbered */
+      *aRv = -1;
+      break;
+    } else {
+      while ((c >= '0') && (c <= '9')) {
+        c = *p++;
+      }
+    }
+
+    /* precision */
+    if (c == '.') {
+      c = *p++;
+      if (c == '*') {
+        /* not supported feature, for the argument is not numbered */
+        *aRv = -1;
+        break;
+      } else {
+        while ((c >= '0') && (c <= '9')) {
+          c = *p++;
+        }
+      }
+    }
+
+    /* size */
+    nas[cn].type = NumArgState::INTN;
+    if (c == 'h') {
+      nas[cn].type = NumArgState::INT16;
+      c = *p++;
+    } else if (c == 'L') {
+      /* XXX not quite sure here */
+      nas[cn].type = NumArgState::INT64;
+      c = *p++;
+    } else if (c == 'l') {
+      nas[cn].type = NumArgState::INT32;
+      c = *p++;
+      if (c == 'l') {
+        nas[cn].type = NumArgState::INT64;
+        c = *p++;
+      }
+    }
+
+    /* format */
+    switch (c) {
+      case 'd':
+      case 'c':
+      case 'i':
+      case 'o':
+      case 'u':
+      case 'x':
+      case 'X':
+        break;
+
+      case 'e':
+      case 'f':
+      case 'g':
+        nas[cn].type = NumArgState::DOUBLE;
+        break;
+
+      case 'p':
+        /* XXX should use cpp */
+        if (sizeof(void*) == sizeof(int32_t)) {
+          nas[cn].type = NumArgState::UINT32;
+        } else if (sizeof(void*) == sizeof(int64_t)) {
+          nas[cn].type = NumArgState::UINT64;
+        } else if (sizeof(void*) == sizeof(int)) {
+          nas[cn].type = NumArgState::UINTN;
+        } else {
+          nas[cn].type = NumArgState::UNKNOWN;
+        }
+        break;
+
+      case 'C':
+        /* XXX not supported I suppose */
+        PR_ASSERT(0);
+        nas[cn].type = NumArgState::UNKNOWN;
+        break;
+
+      case 'S':
+        nas[cn].type = NumArgState::UNISTRING;
+        break;
+
+      case 's':
+        nas[cn].type = NumArgState::STRING;
+        break;
+
+      case 'n':
+        nas[cn].type = NumArgState::INTSTR;
+        break;
+
+      default:
+        PR_ASSERT(0);
+        nas[cn].type = NumArgState::UNKNOWN;
+        break;
+    }
+
+    /* get a legal para. */
+    if (nas[cn].type == NumArgState::UNKNOWN) {
+      *aRv = -1;
+      break;
+    }
+  }
+
+
+  /*
+  ** third pass
+  ** fill the nas[cn].ap
+  */
+  if (*aRv < 0) {
+    if (nas != aNasArray) {
+      PR_DELETE(nas);
+    }
+    return nullptr;
+  }
+
+  cn = 0;
+  while (cn < number) {
+    if (nas[cn].type == NumArgState::UNKNOWN) {
+      cn++;
+      continue;
+    }
+
+    VARARGS_ASSIGN(nas[cn].ap, aAp);
+
+    switch (nas[cn].type) {
+      case NumArgState::INT16:
+      case NumArgState::UINT16:
+      case NumArgState::INTN:
+      case NumArgState::UINTN:     (void)va_arg(aAp, int);         break;
+
+      case NumArgState::INT32:     (void)va_arg(aAp, int32_t);     break;
+
+      case NumArgState::UINT32:    (void)va_arg(aAp, uint32_t);    break;
+
+      case NumArgState::INT64:     (void)va_arg(aAp, int64_t);     break;
+
+      case NumArgState::UINT64:    (void)va_arg(aAp, uint64_t);    break;
+
+      case NumArgState::STRING:    (void)va_arg(aAp, char*);       break;
+
+      case NumArgState::INTSTR:    (void)va_arg(aAp, int*);        break;
+
+      case NumArgState::DOUBLE:    (void)va_arg(aAp, double);      break;
+
+      case NumArgState::UNISTRING: (void)va_arg(aAp, char16_t*);   break;
+
+      default:
+        if (nas != aNasArray) {
+          PR_DELETE(nas);
+        }
+        *aRv = -1;
+        va_end(aAp);
+        return nullptr;
+    }
+    cn++;
+  }
+  va_end(aAp);
+  return nas;
+}
+
+
+/*
+** The workhorse sprintf code.
+*/
+static int
+dosprintf(SprintfState* aState, const char16_t* aFmt, va_list aAp)
+{
+  char16_t c;
+  int flags, width, prec, radix, type;
+  union
+  {
+    char16_t ch;
+    int i;
+    long l;
+    int64_t ll;
+    double d;
+    const char* s;
+    const char16_t* S;
+    int* ip;
+  } u;
+  char16_t space = ' ';
+
+  nsAutoString hex;
+  hex.AssignLiteral("0123456789abcdef");
+
+  nsAutoString HEX;
+  HEX.AssignLiteral("0123456789ABCDEF");
+
+  const char16_t* hexp;
+  int rv, i;
+  struct NumArgState* nas = nullptr;
+  struct NumArgState  nasArray[NAS_DEFAULT_NUM];
+
+
+  /*
+  ** build an argument array, IF the aFmt is numbered argument
+  ** list style, to contain the Numbered Argument list pointers
+  */
+  nas = BuildArgArray(aFmt, aAp, &rv, nasArray);
+  if (rv < 0) {
+    /* the aFmt contains error Numbered Argument format, jliu@netscape.com */
+    PR_ASSERT(0);
+    return rv;
+  }
+
+  while ((c = *aFmt++) != 0) {
+    if (c != '%') {
+      rv = (*aState->stuff)(aState, aFmt - 1, 1);
+      if (rv < 0) {
+        va_end(aAp);
+        PR_CHECK_DELETE(nas);
+        return rv;
+      }
+      continue;
+    }
+
+    /*
+    ** Gobble up the % format string. Hopefully we have handled all
+    ** of the strange cases!
+    */
+    flags = 0;
+    c = *aFmt++;
+    if (c == '%') {
+      /* quoting a % with %% */
+      rv = (*aState->stuff)(aState, aFmt - 1, 1);
+      if (rv < 0) {
+        va_end(aAp);
+        PR_CHECK_DELETE(nas);
+        return rv;
+      }
+      continue;
+    }
+
+    if (nas) {
+      /* the aFmt contains the Numbered Arguments feature */
+      i = 0;
+      /* should improve error check later */
+      while (c && c != '$') {
+        i = (i * 10) + (c - '0');
+        c = *aFmt++;
+      }
+
+      if (nas[i - 1].type == NumArgState::UNKNOWN) {
+        if (nas != nasArray) {
+          PR_DELETE(nas);
+        }
+        va_end(aAp);
+        return -1;
+      }
+
+      VARARGS_ASSIGN(aAp, nas[i - 1].ap);
+      c = *aFmt++;
+    }
+
+    /*
+     * Examine optional flags.  Note that we do not implement the
+     * '#' flag of sprintf().  The ANSI C spec. of the '#' flag is
+     * somewhat ambiguous and not ideal, which is perhaps why
+     * the various sprintf() implementations are inconsistent
+     * on this feature.
+     */
+    while ((c == '-') || (c == '+') || (c == ' ') || (c == '0')) {
+      if (c == '-') {
+        flags |= _LEFT;
+      }
+      if (c == '+') {
+        flags |= _SIGNED;
+      }
+      if (c == ' ') {
+        flags |= _SPACED;
+      }
+      if (c == '0') {
+        flags |= _ZEROS;
+      }
+      c = *aFmt++;
+    }
+    if (flags & _SIGNED) {
+      flags &= ~_SPACED;
+    }
+    if (flags & _LEFT) {
+      flags &= ~_ZEROS;
+    }
+
+    /* width */
+    if (c == '*') {
+      c = *aFmt++;
+      width = va_arg(aAp, int);
+    } else {
+      width = 0;
+      while ((c >= '0') && (c <= '9')) {
+        width = (width * 10) + (c - '0');
+        c = *aFmt++;
+      }
+    }
+
+    /* precision */
+    prec = -1;
+    if (c == '.') {
+      c = *aFmt++;
+      if (c == '*') {
+        c = *aFmt++;
+        prec = va_arg(aAp, int);
+      } else {
+        prec = 0;
+        while ((c >= '0') && (c <= '9')) {
+          prec = (prec * 10) + (c - '0');
+          c = *aFmt++;
+        }
+      }
+    }
+
+    /* size */
+    type = NumArgState::INTN;
+    if (c == 'h') {
+      type = NumArgState::INT16;
+      c = *aFmt++;
+    } else if (c == 'L') {
+      /* XXX not quite sure here */
+      type = NumArgState::INT64;
+      c = *aFmt++;
+    } else if (c == 'l') {
+      type = NumArgState::INT32;
+      c = *aFmt++;
+      if (c == 'l') {
+        type = NumArgState::INT64;
+        c = *aFmt++;
+      }
+    }
+
+    /* format */
+    hexp = hex.get();
+    switch (c) {
+      case 'd':
+      case 'i':                               /* decimal/integer */
+        radix = 10;
+        goto fetch_and_convert;
+
+      case 'o':                               /* octal */
+        radix = 8;
+        type |= 1;
+        goto fetch_and_convert;
+
+      case 'u':                               /* unsigned decimal */
+        radix = 10;
+        type |= 1;
+        goto fetch_and_convert;
+
+      case 'x':                               /* unsigned hex */
+        radix = 16;
+        type |= 1;
+        goto fetch_and_convert;
+
+      case 'X':                               /* unsigned HEX */
+        radix = 16;
+        hexp = HEX.get();
+        type |= 1;
+        goto fetch_and_convert;
+
+        fetch_and_convert:
+        switch (type) {
+          case NumArgState::INT16:
+            u.l = va_arg(aAp, int);
+            if (u.l < 0) {
+              u.l = -u.l;
+              flags |= _NEG;
+            }
+            goto do_long;
+          case NumArgState::UINT16:
+            u.l = va_arg(aAp, int) & 0xffff;
+            goto do_long;
+          case NumArgState::INTN:
+            u.l = va_arg(aAp, int);
+            if (u.l < 0) {
+              u.l = -u.l;
+              flags |= _NEG;
+            }
+            goto do_long;
+          case NumArgState::UINTN:
+            u.l = (long)va_arg(aAp, unsigned int);
+            goto do_long;
+
+          case NumArgState::INT32:
+            u.l = va_arg(aAp, int32_t);
+            if (u.l < 0) {
+              u.l = -u.l;
+              flags |= _NEG;
+            }
+            goto do_long;
+          case NumArgState::UINT32:
+            u.l = (long)va_arg(aAp, uint32_t);
+          do_long:
+            rv = cvt_l(aState, u.l, width, prec, radix, type, flags, hexp);
+            if (rv < 0) {
+              va_end(aAp);
+              PR_CHECK_DELETE(nas);
+              return rv;
+            }
+            break;
+
+          case NumArgState::INT64:
+            u.ll = va_arg(aAp, int64_t);
+            if (u.ll < 0) {
+              u.ll = -u.ll;
+              flags |= _NEG;
+            }
+            goto do_longlong;
+          case NumArgState::UINT64:
+            u.ll = va_arg(aAp, uint64_t);
+          do_longlong:
+            rv = cvt_ll(aState, u.ll, width, prec, radix, type, flags, hexp);
+            if (rv < 0) {
+              va_end(aAp);
+              PR_CHECK_DELETE(nas);
+              return rv;
+            }
+            break;
+        }
+        break;
+
+      case 'e':
+      case 'E':
+      case 'f':
+      case 'g':
+      case 'G':
+        u.d = va_arg(aAp, double);
+        rv = cvt_f(aState, u.d, width, prec, c, flags);
+        if (rv < 0) {
+          return rv;
+        }
+        break;
+
+      case 'c':
+        u.ch = va_arg(aAp, int);
+        if ((flags & _LEFT) == 0) {
+          while (width-- > 1) {
+            rv = (*aState->stuff)(aState, &space, 1);
+            if (rv < 0) {
+              va_end(aAp);
+              PR_CHECK_DELETE(nas);
+              return rv;
+            }
+          }
+        }
+        rv = (*aState->stuff)(aState, &u.ch, 1);
+        if (rv < 0) {
+          va_end(aAp);
+          PR_CHECK_DELETE(nas);
+          return rv;
+        }
+        if (flags & _LEFT) {
+          while (width-- > 1) {
+            rv = (*aState->stuff)(aState, &space, 1);
+            if (rv < 0) {
+              va_end(aAp);
+              PR_CHECK_DELETE(nas);
+              return rv;
+            }
+          }
+        }
+        break;
+
+      case 'p':
+        if (sizeof(void*) == sizeof(int32_t)) {
+          type = NumArgState::UINT32;
+        } else if (sizeof(void*) == sizeof(int64_t)) {
+          type = NumArgState::UINT64;
+        } else if (sizeof(void*) == sizeof(int)) {
+          type = NumArgState::UINTN;
+        } else {
+          PR_ASSERT(0);
+          break;
+        }
+        radix = 16;
+        goto fetch_and_convert;
+
+#if 0
+      case 'C':
+        /* XXX not supported I suppose */
+        PR_ASSERT(0);
+        break;
+#endif
+
+      case 'S':
+        u.S = va_arg(aAp, const char16_t*);
+        rv = cvt_S(aState, u.S, width, prec, flags);
+        if (rv < 0) {
+          va_end(aAp);
+          PR_CHECK_DELETE(nas);
+          return rv;
+        }
+        break;
+
+      case 's':
+        u.s = va_arg(aAp, const char*);
+        rv = cvt_s(aState, u.s, width, prec, flags);
+        if (rv < 0) {
+          va_end(aAp);
+          PR_CHECK_DELETE(nas);
+          return rv;
+        }
+        break;
+
+      case 'n':
+        u.ip = va_arg(aAp, int*);
+        if (u.ip) {
+          *u.ip = aState->cur - aState->base;
+        }
+        break;
+
+      default:
+        /* Not a % token after all... skip it */
+#if 0
+        PR_ASSERT(0);
+#endif
+        char16_t perct = '%';
+        rv = (*aState->stuff)(aState, &perct, 1);
+        if (rv < 0) {
+          va_end(aAp);
+          PR_CHECK_DELETE(nas);
+          return rv;
+        }
+        rv = (*aState->stuff)(aState, aFmt - 1, 1);
+        if (rv < 0) {
+          va_end(aAp);
+          PR_CHECK_DELETE(nas);
+          return rv;
+        }
+    }
+  }
+
+  /* Stuff trailing NUL */
+  char16_t null = '\0';
+
+  rv = (*aState->stuff)(aState, &null, 1);
+
+  va_end(aAp);
+  PR_CHECK_DELETE(nas);
+
+  return rv;
+}
+
+/************************************************************************/
+
+static int
+StringStuff(SprintfState* aState, const char16_t* aStr, uint32_t aLen)
+{
+  if (*aStr == '\0') {
+    return 0;
+  }
+
+  ptrdiff_t off = aState->cur - aState->base;
+
+  nsAString* str = static_cast<nsAString*>(aState->stuffclosure);
+  str->Append(aStr, aLen);
+
+  aState->base = str->BeginWriting();
+  aState->cur = aState->base + off;
+
+  return 0;
+}
+
+/*
+** Stuff routine that automatically grows the malloc'd output buffer
+** before it overflows.
+*/
+static int
+GrowStuff(SprintfState* aState, const char16_t* aStr, uint32_t aLen)
+{
+  ptrdiff_t off;
+  char16_t* newbase;
+  uint32_t newlen;
+
+  off = aState->cur - aState->base;
+  if (off + aLen >= aState->maxlen) {
+    /* Grow the buffer */
+    newlen = aState->maxlen + ((aLen > 32) ? aLen : 32);
+    if (aState->base) {
+      newbase = (char16_t*)moz_xrealloc(aState->base,
+                                        newlen * sizeof(char16_t));
+    } else {
+      newbase = (char16_t*)moz_xmalloc(newlen * sizeof(char16_t));
+    }
+    if (!newbase) {
+      /* Ran out of memory */
+      return -1;
+    }
+    aState->base = newbase;
+    aState->maxlen = newlen;
+    aState->cur = aState->base + off;
+  }
+
+  /* Copy data */
+  while (aLen) {
+    --aLen;
+    *aState->cur++ = *aStr++;
+  }
+  MOZ_ASSERT((uint32_t)(aState->cur - aState->base) <= aState->maxlen);
+  return 0;
+}
+
+/*
+** sprintf into a malloc'd buffer
+*/
+char16_t*
+nsTextFormatter::smprintf(const char16_t* aFmt, ...)
+{
+  va_list ap;
+  char16_t* rv;
+
+  va_start(ap, aFmt);
+  rv = nsTextFormatter::vsmprintf(aFmt, ap);
+  va_end(ap);
+  return rv;
+}
+
+uint32_t
+nsTextFormatter::ssprintf(nsAString& aOut, const char16_t* aFmt, ...)
+{
+  va_list ap;
+  uint32_t rv;
+
+  va_start(ap, aFmt);
+  rv = nsTextFormatter::vssprintf(aOut, aFmt, ap);
+  va_end(ap);
+  return rv;
+}
+
+uint32_t
+nsTextFormatter::vssprintf(nsAString& aOut, const char16_t* aFmt, va_list aAp)
+{
+  SprintfState ss;
+  ss.stuff = StringStuff;
+  ss.base = 0;
+  ss.cur = 0;
+  ss.maxlen = 0;
+  ss.stuffclosure = &aOut;
+
+  aOut.Truncate();
+  int n = dosprintf(&ss, aFmt, aAp);
+  return n ? n - 1 : n;
+}
+
+char16_t*
+nsTextFormatter::vsmprintf(const char16_t* aFmt, va_list aAp)
+{
+  SprintfState ss;
+  int rv;
+
+  ss.stuff = GrowStuff;
+  ss.base = 0;
+  ss.cur = 0;
+  ss.maxlen = 0;
+  rv = dosprintf(&ss, aFmt, aAp);
+  if (rv < 0) {
+    if (ss.base) {
+      PR_DELETE(ss.base);
+    }
+    return 0;
+  }
+  return ss.base;
+}
+
+/*
+** Stuff routine that discards overflow data
+*/
+static int
+LimitStuff(SprintfState* aState, const char16_t* aStr, uint32_t aLen)
+{
+  uint32_t limit = aState->maxlen - (aState->cur - aState->base);
+
+  if (aLen > limit) {
+    aLen = limit;
+  }
+  while (aLen) {
+    --aLen;
+    *aState->cur++ = *aStr++;
+  }
+  return 0;
+}
+
+/*
+** sprintf into a fixed size buffer. Make sure there is a NUL at the end
+** when finished.
+*/
+uint32_t
+nsTextFormatter::snprintf(char16_t* aOut, uint32_t aOutLen,
+                          const char16_t* aFmt, ...)
+{
+  va_list ap;
+  uint32_t rv;
+
+  MOZ_ASSERT((int32_t)aOutLen > 0);
+  if ((int32_t)aOutLen <= 0) {
+    return 0;
+  }
+
+  va_start(ap, aFmt);
+  rv = nsTextFormatter::vsnprintf(aOut, aOutLen, aFmt, ap);
+  va_end(ap);
+  return rv;
+}
+
+uint32_t
+nsTextFormatter::vsnprintf(char16_t* aOut, uint32_t aOutLen,
+                           const char16_t* aFmt, va_list aAp)
+{
+  SprintfState ss;
+  uint32_t n;
+
+  MOZ_ASSERT((int32_t)aOutLen > 0);
+  if ((int32_t)aOutLen <= 0) {
+    return 0;
+  }
+
+  ss.stuff = LimitStuff;
+  ss.base = aOut;
+  ss.cur = aOut;
+  ss.maxlen = aOutLen;
+  (void) dosprintf(&ss, aFmt, aAp);
+
+  /* If we added chars, and we didn't append a null, do it now. */
+  if ((ss.cur != ss.base) && (*(ss.cur - 1) != '\0')) {
+    *(--ss.cur) = '\0';
+  }
+
+  n = ss.cur - ss.base;
+  return n ? n - 1 : n;
+}
+
+/*
+ * Free memory allocated, for the caller, by smprintf
+ */
+void
+nsTextFormatter::smprintf_free(char16_t* aMem)
+{
+  free(aMem);
+}
+
diff --git a/xpcom/glue/nsTextFormatter.h b/xpcom/glue/nsTextFormatter.h
new file mode 100644
index 0000000000..4cd44be320
--- /dev/null
+++ b/xpcom/glue/nsTextFormatter.h
@@ -0,0 +1,80 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * This code was copied from xpcom/ds/nsTextFormatter r1.3
+ *           Memory model and Frozen linkage changes only.
+ *                           -- Prasad <prasad@medhas.org>
+ */
+
+#ifndef nsTextFormatter_h___
+#define nsTextFormatter_h___
+
+/*
+ ** API for PR printf like routines. Supports the following formats
+ **	%d - decimal
+ **	%u - unsigned decimal
+ **	%x - unsigned hex
+ **	%X - unsigned uppercase hex
+ **	%o - unsigned octal
+ **	%hd, %hu, %hx, %hX, %ho - 16-bit versions of above
+ **	%ld, %lu, %lx, %lX, %lo - 32-bit versions of above
+ **	%lld, %llu, %llx, %llX, %llo - 64 bit versions of above
+ **	%s - utf8 string
+ **	%S - char16_t string
+ **	%c - character
+ **	%p - pointer (deals with machine dependent pointer size)
+ **	%f - float
+ **	%g - float
+ */
+#include "prio.h"
+#include <stdio.h>
+#include <stdarg.h>
+#include "nscore.h"
+#include "nsStringGlue.h"
+
+#ifdef XPCOM_GLUE
+#error "nsTextFormatter is not available in the standalone glue due to NSPR dependencies."
+#endif
+
+class nsTextFormatter
+{
+public:
+
+  /*
+   * sprintf into a fixed size buffer. Guarantees that the buffer is null
+   * terminated. Returns the length of the written output, NOT including the
+   * null terminator, or (uint32_t)-1 if an error occurs.
+   */
+  static uint32_t snprintf(char16_t* aOut, uint32_t aOutLen,
+                           const char16_t* aFmt, ...);
+
+  /*
+   * sprintf into a moz_xmalloc'd buffer. Return a pointer to
+   * buffer on success, nullptr on failure.
+   */
+  static char16_t* smprintf(const char16_t* aFmt, ...);
+
+  static uint32_t ssprintf(nsAString& aOut, const char16_t* aFmt, ...);
+
+  /*
+   * va_list forms of the above.
+   */
+  static uint32_t vsnprintf(char16_t* aOut, uint32_t aOutLen, const char16_t* aFmt,
+                            va_list aAp);
+  static char16_t* vsmprintf(const char16_t* aFmt, va_list aAp);
+  static uint32_t vssprintf(nsAString& aOut, const char16_t* aFmt, va_list aAp);
+
+  /*
+   * Free the memory allocated, for the caller, by smprintf.
+   * -- Deprecated --
+   * Callers can substitute calling smprintf_free with free
+   */
+  static void smprintf_free(char16_t* aMem);
+
+};
+
+#endif /* nsTextFormatter_h___ */
diff --git a/xpcom/glue/nsThreadUtils.cpp b/xpcom/glue/nsThreadUtils.cpp
new file mode 100644
index 0000000000..287ada7bef
--- /dev/null
+++ b/xpcom/glue/nsThreadUtils.cpp
@@ -0,0 +1,472 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsThreadUtils.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Likely.h"
+#include "mozilla/TimeStamp.h"
+#include "LeakRefPtr.h"
+
+#ifdef MOZILLA_INTERNAL_API
+# include "nsThreadManager.h"
+#else
+# include "nsXPCOMCIDInternal.h"
+# include "nsIThreadManager.h"
+# include "nsServiceManagerUtils.h"
+#endif
+
+#ifdef XP_WIN
+#include <windows.h>
+#include "mozilla/WindowsVersion.h"
+using mozilla::IsVistaOrLater;
+#elif defined(XP_MACOSX)
+#include <sys/resource.h>
+#endif
+
+#include <pratom.h>
+#include <prthread.h>
+
+using namespace mozilla;
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+
+NS_IMPL_ISUPPORTS(IdlePeriod, nsIIdlePeriod)
+
+NS_IMETHODIMP
+IdlePeriod::GetIdlePeriodHint(TimeStamp* aIdleDeadline)
+{
+  *aIdleDeadline = TimeStamp();
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(Runnable, nsIRunnable)
+
+NS_IMETHODIMP
+Runnable::Run()
+{
+  // Do nothing
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS_INHERITED(CancelableRunnable, Runnable,
+                            nsICancelableRunnable)
+
+nsresult
+CancelableRunnable::Cancel()
+{
+  // Do nothing
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS_INHERITED(IncrementalRunnable, CancelableRunnable,
+                            nsIIncrementalRunnable)
+
+void
+IncrementalRunnable::SetDeadline(TimeStamp aDeadline)
+{
+  // Do nothing
+}
+
+#endif  // XPCOM_GLUE_AVOID_NSPR
+
+//-----------------------------------------------------------------------------
+
+nsresult
+NS_NewThread(nsIThread** aResult, nsIRunnable* aEvent, uint32_t aStackSize)
+{
+  nsCOMPtr<nsIThread> thread;
+#ifdef MOZILLA_INTERNAL_API
+  nsresult rv =
+    nsThreadManager::get().nsThreadManager::NewThread(0, aStackSize,
+                                                      getter_AddRefs(thread));
+#else
+  nsresult rv;
+  nsCOMPtr<nsIThreadManager> mgr =
+    do_GetService(NS_THREADMANAGER_CONTRACTID, &rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = mgr->NewThread(0, aStackSize, getter_AddRefs(thread));
+#endif
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  if (aEvent) {
+    rv = thread->Dispatch(aEvent, NS_DISPATCH_NORMAL);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  *aResult = nullptr;
+  thread.swap(*aResult);
+  return NS_OK;
+}
+
+nsresult
+NS_GetCurrentThread(nsIThread** aResult)
+{
+#ifdef MOZILLA_INTERNAL_API
+  return nsThreadManager::get().nsThreadManager::GetCurrentThread(aResult);
+#else
+  nsresult rv;
+  nsCOMPtr<nsIThreadManager> mgr =
+    do_GetService(NS_THREADMANAGER_CONTRACTID, &rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  return mgr->GetCurrentThread(aResult);
+#endif
+}
+
+nsresult
+NS_GetMainThread(nsIThread** aResult)
+{
+#ifdef MOZILLA_INTERNAL_API
+  return nsThreadManager::get().nsThreadManager::GetMainThread(aResult);
+#else
+  nsresult rv;
+  nsCOMPtr<nsIThreadManager> mgr =
+    do_GetService(NS_THREADMANAGER_CONTRACTID, &rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  return mgr->GetMainThread(aResult);
+#endif
+}
+
+#ifndef MOZILLA_INTERNAL_API
+bool
+NS_IsMainThread()
+{
+  bool result = false;
+  nsCOMPtr<nsIThreadManager> mgr =
+    do_GetService(NS_THREADMANAGER_CONTRACTID);
+  if (mgr) {
+    mgr->GetIsMainThread(&result);
+  }
+  return bool(result);
+}
+#endif
+
+nsresult
+NS_DispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent)
+{
+  nsresult rv;
+  nsCOMPtr<nsIRunnable> event(aEvent);
+#ifdef MOZILLA_INTERNAL_API
+  nsIThread* thread = NS_GetCurrentThread();
+  if (!thread) {
+    return NS_ERROR_UNEXPECTED;
+  }
+#else
+  nsCOMPtr<nsIThread> thread;
+  rv = NS_GetCurrentThread(getter_AddRefs(thread));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+#endif
+  // To keep us from leaking the runnable if dispatch method fails,
+  // we grab the reference on failures and release it.
+  nsIRunnable* temp = event.get();
+  rv = thread->Dispatch(event.forget(), NS_DISPATCH_NORMAL);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    // Dispatch() leaked the reference to the event, but due to caller's
+    // assumptions, we shouldn't leak here. And given we are on the same
+    // thread as the dispatch target, it's mostly safe to do it here.
+    NS_RELEASE(temp);
+  }
+  return rv;
+}
+
+// It is common to call NS_DispatchToCurrentThread with a newly
+// allocated runnable with a refcount of zero. To keep us from leaking
+// the runnable if the dispatch method fails, we take a death grip.
+nsresult
+NS_DispatchToCurrentThread(nsIRunnable* aEvent)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+  return NS_DispatchToCurrentThread(event.forget());
+}
+
+nsresult
+NS_DispatchToMainThread(already_AddRefed<nsIRunnable>&& aEvent, uint32_t aDispatchFlags)
+{
+  LeakRefPtr<nsIRunnable> event(Move(aEvent));
+  nsCOMPtr<nsIThread> thread;
+  nsresult rv = NS_GetMainThread(getter_AddRefs(thread));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    NS_ASSERTION(false, "Failed NS_DispatchToMainThread() in shutdown; leaking");
+    // NOTE: if you stop leaking here, adjust Promise::MaybeReportRejected(),
+    // which assumes a leak here, or split into leaks and no-leaks versions
+    return rv;
+  }
+  return thread->Dispatch(event.take(), aDispatchFlags);
+}
+
+// In the case of failure with a newly allocated runnable with a
+// refcount of zero, we intentionally leak the runnable, because it is
+// likely that the runnable is being dispatched to the main thread
+// because it owns main thread only objects, so it is not safe to
+// release them here.
+nsresult
+NS_DispatchToMainThread(nsIRunnable* aEvent, uint32_t aDispatchFlags)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+  return NS_DispatchToMainThread(event.forget(), aDispatchFlags);
+}
+
+nsresult
+NS_DelayedDispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent, uint32_t aDelayMs)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+#ifdef MOZILLA_INTERNAL_API
+  nsIThread* thread = NS_GetCurrentThread();
+  if (!thread) {
+    return NS_ERROR_UNEXPECTED;
+  }
+#else
+  nsresult rv;
+  nsCOMPtr<nsIThread> thread;
+  rv = NS_GetCurrentThread(getter_AddRefs(thread));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+#endif
+
+  return thread->DelayedDispatch(event.forget(), aDelayMs);
+}
+
+nsresult
+NS_IdleDispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent)
+{
+  nsresult rv;
+  nsCOMPtr<nsIRunnable> event(aEvent);
+#ifdef MOZILLA_INTERNAL_API
+  nsIThread* thread = NS_GetCurrentThread();
+  if (!thread) {
+    return NS_ERROR_UNEXPECTED;
+  }
+#else
+  nsCOMPtr<nsIThread> thread;
+  rv = NS_GetCurrentThread(getter_AddRefs(thread));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+#endif
+  // To keep us from leaking the runnable if dispatch method fails,
+  // we grab the reference on failures and release it.
+  nsIRunnable* temp = event.get();
+  rv = thread->IdleDispatch(event.forget());
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    // Dispatch() leaked the reference to the event, but due to caller's
+    // assumptions, we shouldn't leak here. And given we are on the same
+    // thread as the dispatch target, it's mostly safe to do it here.
+    NS_RELEASE(temp);
+  }
+
+  return rv;
+}
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+nsresult
+NS_ProcessPendingEvents(nsIThread* aThread, PRIntervalTime aTimeout)
+{
+  nsresult rv = NS_OK;
+
+#ifdef MOZILLA_INTERNAL_API
+  if (!aThread) {
+    aThread = NS_GetCurrentThread();
+    if (NS_WARN_IF(!aThread)) {
+      return NS_ERROR_UNEXPECTED;
+    }
+  }
+#else
+  nsCOMPtr<nsIThread> current;
+  if (!aThread) {
+    rv = NS_GetCurrentThread(getter_AddRefs(current));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+    aThread = current.get();
+  }
+#endif
+
+  PRIntervalTime start = PR_IntervalNow();
+  for (;;) {
+    bool processedEvent;
+    rv = aThread->ProcessNextEvent(false, &processedEvent);
+    if (NS_FAILED(rv) || !processedEvent) {
+      break;
+    }
+    if (PR_IntervalNow() - start > aTimeout) {
+      break;
+    }
+  }
+  return rv;
+}
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+inline bool
+hasPendingEvents(nsIThread* aThread)
+{
+  bool val;
+  return NS_SUCCEEDED(aThread->HasPendingEvents(&val)) && val;
+}
+
+bool
+NS_HasPendingEvents(nsIThread* aThread)
+{
+  if (!aThread) {
+#ifndef MOZILLA_INTERNAL_API
+    nsCOMPtr<nsIThread> current;
+    NS_GetCurrentThread(getter_AddRefs(current));
+    return hasPendingEvents(current);
+#else
+    aThread = NS_GetCurrentThread();
+    if (NS_WARN_IF(!aThread)) {
+      return false;
+    }
+#endif
+  }
+  return hasPendingEvents(aThread);
+}
+
+bool
+NS_ProcessNextEvent(nsIThread* aThread, bool aMayWait)
+{
+#ifdef MOZILLA_INTERNAL_API
+  if (!aThread) {
+    aThread = NS_GetCurrentThread();
+    if (NS_WARN_IF(!aThread)) {
+      return false;
+    }
+  }
+#else
+  nsCOMPtr<nsIThread> current;
+  if (!aThread) {
+    NS_GetCurrentThread(getter_AddRefs(current));
+    if (NS_WARN_IF(!current)) {
+      return false;
+    }
+    aThread = current.get();
+  }
+#endif
+  bool val;
+  return NS_SUCCEEDED(aThread->ProcessNextEvent(aMayWait, &val)) && val;
+}
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+
+namespace {
+
+class nsNameThreadRunnable final : public nsIRunnable
+{
+  ~nsNameThreadRunnable() {}
+
+public:
+  explicit nsNameThreadRunnable(const nsACString& aName) : mName(aName) {}
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIRUNNABLE
+
+protected:
+  const nsCString mName;
+};
+
+NS_IMPL_ISUPPORTS(nsNameThreadRunnable, nsIRunnable)
+
+NS_IMETHODIMP
+nsNameThreadRunnable::Run()
+{
+  PR_SetCurrentThreadName(mName.BeginReading());
+  return NS_OK;
+}
+
+} // namespace
+
+void
+NS_SetThreadName(nsIThread* aThread, const nsACString& aName)
+{
+  if (!aThread) {
+    return;
+  }
+
+  aThread->Dispatch(new nsNameThreadRunnable(aName),
+                    nsIEventTarget::DISPATCH_NORMAL);
+}
+
+#else // !XPCOM_GLUE_AVOID_NSPR
+
+void
+NS_SetThreadName(nsIThread* aThread, const nsACString& aName)
+{
+  // No NSPR, no love.
+}
+
+#endif
+
+#ifdef MOZILLA_INTERNAL_API
+nsIThread*
+NS_GetCurrentThread()
+{
+  return nsThreadManager::get().GetCurrentThread();
+}
+#endif
+
+// nsThreadPoolNaming
+void
+nsThreadPoolNaming::SetThreadPoolName(const nsACString& aPoolName,
+                                      nsIThread* aThread)
+{
+  nsCString name(aPoolName);
+  name.AppendLiteral(" #");
+  name.AppendInt(++mCounter, 10); // The counter is declared as volatile
+
+  if (aThread) {
+    // Set on the target thread
+    NS_SetThreadName(aThread, name);
+  } else {
+    // Set on the current thread
+#ifndef XPCOM_GLUE_AVOID_NSPR
+    PR_SetCurrentThreadName(name.BeginReading());
+#endif
+  }
+}
+
+// nsAutoLowPriorityIO
+nsAutoLowPriorityIO::nsAutoLowPriorityIO()
+{
+#if defined(XP_WIN)
+  lowIOPrioritySet = IsVistaOrLater() &&
+                     SetThreadPriority(GetCurrentThread(),
+                                       THREAD_MODE_BACKGROUND_BEGIN);
+#elif defined(XP_MACOSX)
+  oldPriority = getiopolicy_np(IOPOL_TYPE_DISK, IOPOL_SCOPE_THREAD);
+  lowIOPrioritySet = oldPriority != -1 &&
+                     setiopolicy_np(IOPOL_TYPE_DISK,
+                                    IOPOL_SCOPE_THREAD,
+                                    IOPOL_THROTTLE) != -1;
+#else
+  lowIOPrioritySet = false;
+#endif
+}
+
+nsAutoLowPriorityIO::~nsAutoLowPriorityIO()
+{
+#if defined(XP_WIN)
+  if (MOZ_LIKELY(lowIOPrioritySet)) {
+    // On Windows the old thread priority is automatically restored
+    SetThreadPriority(GetCurrentThread(), THREAD_MODE_BACKGROUND_END);
+  }
+#elif defined(XP_MACOSX)
+  if (MOZ_LIKELY(lowIOPrioritySet)) {
+    setiopolicy_np(IOPOL_TYPE_DISK, IOPOL_SCOPE_THREAD, oldPriority);
+  }
+#endif
+}
diff --git a/xpcom/glue/nsThreadUtils.h b/xpcom/glue/nsThreadUtils.h
new file mode 100644
index 0000000000..cbd7f78421
--- /dev/null
+++ b/xpcom/glue/nsThreadUtils.h
@@ -0,0 +1,1049 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsThreadUtils_h__
+#define nsThreadUtils_h__
+
+#include "prthread.h"
+#include "prinrval.h"
+#include "MainThreadUtils.h"
+#include "nsIThreadManager.h"
+#include "nsIThread.h"
+#include "nsIRunnable.h"
+#include "nsICancelableRunnable.h"
+#include "nsIIdlePeriod.h"
+#include "nsIIncrementalRunnable.h"
+#include "nsStringGlue.h"
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/IndexSequence.h"
+#include "mozilla/Likely.h"
+#include "mozilla/Move.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/Tuple.h"
+#include "mozilla/TypeTraits.h"
+
+//-----------------------------------------------------------------------------
+// These methods are alternatives to the methods on nsIThreadManager, provided
+// for convenience.
+
+/**
+ * Set name of the target thread.  This operation is asynchronous.
+ */
+extern void NS_SetThreadName(nsIThread* aThread, const nsACString& aName);
+
+/**
+ * Static length version of the above function checking length of the
+ * name at compile time.
+ */
+template<size_t LEN>
+inline void
+NS_SetThreadName(nsIThread* aThread, const char (&aName)[LEN])
+{
+  static_assert(LEN <= 16,
+                "Thread name must be no more than 16 characters");
+  NS_SetThreadName(aThread, nsDependentCString(aName));
+}
+
+/**
+ * Create a new thread, and optionally provide an initial event for the thread.
+ *
+ * @param aResult
+ *   The resulting nsIThread object.
+ * @param aInitialEvent
+ *   The initial event to run on this thread.  This parameter may be null.
+ * @param aStackSize
+ *   The size in bytes to reserve for the thread's stack.
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   Indicates that the given name is not unique.
+ */
+extern nsresult
+NS_NewThread(nsIThread** aResult,
+             nsIRunnable* aInitialEvent = nullptr,
+             uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE);
+
+/**
+ * Creates a named thread, otherwise the same as NS_NewThread
+ */
+template<size_t LEN>
+inline nsresult
+NS_NewNamedThread(const char (&aName)[LEN],
+                  nsIThread** aResult,
+                  nsIRunnable* aInitialEvent = nullptr,
+                  uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE)
+{
+  // Hold a ref while dispatching the initial event to match NS_NewThread()
+  nsCOMPtr<nsIThread> thread;
+  nsresult rv = NS_NewThread(getter_AddRefs(thread), nullptr, aStackSize);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  NS_SetThreadName<LEN>(thread, aName);
+  if (aInitialEvent) {
+    rv = thread->Dispatch(aInitialEvent, NS_DISPATCH_NORMAL);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Initial event dispatch failed");
+  }
+
+  *aResult = nullptr;
+  thread.swap(*aResult);
+  return rv;
+}
+
+/**
+ * Get a reference to the current thread.
+ *
+ * @param aResult
+ *   The resulting nsIThread object.
+ */
+extern nsresult NS_GetCurrentThread(nsIThread** aResult);
+
+/**
+ * Dispatch the given event to the current thread.
+ *
+ * @param aEvent
+ *   The event to dispatch.
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   If event is null.
+ */
+extern nsresult NS_DispatchToCurrentThread(nsIRunnable* aEvent);
+extern nsresult
+NS_DispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent);
+
+/**
+ * Dispatch the given event to the main thread.
+ *
+ * @param aEvent
+ *   The event to dispatch.
+ * @param aDispatchFlags
+ *   The flags to pass to the main thread's dispatch method.
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   If event is null.
+ */
+extern nsresult
+NS_DispatchToMainThread(nsIRunnable* aEvent,
+                        uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
+extern nsresult
+NS_DispatchToMainThread(already_AddRefed<nsIRunnable>&& aEvent,
+                        uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
+
+extern nsresult
+NS_DelayedDispatchToCurrentThread(
+  already_AddRefed<nsIRunnable>&& aEvent, uint32_t aDelayMs);
+
+extern nsresult
+NS_IdleDispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+/**
+ * Process all pending events for the given thread before returning.  This
+ * method simply calls ProcessNextEvent on the thread while HasPendingEvents
+ * continues to return true and the time spent in NS_ProcessPendingEvents
+ * does not exceed the given timeout value.
+ *
+ * @param aThread
+ *   The thread object for which to process pending events.  If null, then
+ *   events will be processed for the current thread.
+ * @param aTimeout
+ *   The maximum number of milliseconds to spend processing pending events.
+ *   Events are not pre-empted to honor this timeout.  Rather, the timeout
+ *   value is simply used to determine whether or not to process another event.
+ *   Pass PR_INTERVAL_NO_TIMEOUT to specify no timeout.
+ */
+extern nsresult
+NS_ProcessPendingEvents(nsIThread* aThread,
+                        PRIntervalTime aTimeout = PR_INTERVAL_NO_TIMEOUT);
+#endif
+
+/**
+ * Shortcut for nsIThread::HasPendingEvents.
+ *
+ * It is an error to call this function when the given thread is not the
+ * current thread.  This function will return false if called from some
+ * other thread.
+ *
+ * @param aThread
+ *   The current thread or null.
+ *
+ * @returns
+ *   A boolean value that if "true" indicates that there are pending events
+ *   in the current thread's event queue.
+ */
+extern bool NS_HasPendingEvents(nsIThread* aThread = nullptr);
+
+/**
+ * Shortcut for nsIThread::ProcessNextEvent.
+ *
+ * It is an error to call this function when the given thread is not the
+ * current thread.  This function will simply return false if called
+ * from some other thread.
+ *
+ * @param aThread
+ *   The current thread or null.
+ * @param aMayWait
+ *   A boolean parameter that if "true" indicates that the method may block
+ *   the calling thread to wait for a pending event.
+ *
+ * @returns
+ *   A boolean value that if "true" indicates that an event from the current
+ *   thread's event queue was processed.
+ */
+extern bool NS_ProcessNextEvent(nsIThread* aThread = nullptr,
+                                bool aMayWait = true);
+
+//-----------------------------------------------------------------------------
+// Helpers that work with nsCOMPtr:
+
+inline already_AddRefed<nsIThread>
+do_GetCurrentThread()
+{
+  nsIThread* thread = nullptr;
+  NS_GetCurrentThread(&thread);
+  return already_AddRefed<nsIThread>(thread);
+}
+
+inline already_AddRefed<nsIThread>
+do_GetMainThread()
+{
+  nsIThread* thread = nullptr;
+  NS_GetMainThread(&thread);
+  return already_AddRefed<nsIThread>(thread);
+}
+
+//-----------------------------------------------------------------------------
+
+#ifdef MOZILLA_INTERNAL_API
+// Fast access to the current thread.  Do not release the returned pointer!  If
+// you want to use this pointer from some other thread, then you will need to
+// AddRef it.  Otherwise, you should only consider this pointer valid from code
+// running on the current thread.
+extern nsIThread* NS_GetCurrentThread();
+#endif
+
+//-----------------------------------------------------------------------------
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+
+namespace mozilla {
+
+// This class is designed to be subclassed.
+class IdlePeriod : public nsIIdlePeriod
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIIDLEPERIOD
+
+  IdlePeriod() {}
+
+protected:
+  virtual ~IdlePeriod() {}
+private:
+  IdlePeriod(const IdlePeriod&) = delete;
+  IdlePeriod& operator=(const IdlePeriod&) = delete;
+  IdlePeriod& operator=(const IdlePeriod&&) = delete;
+};
+
+// This class is designed to be subclassed.
+class Runnable : public nsIRunnable
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIRUNNABLE
+
+  Runnable() {}
+
+protected:
+  virtual ~Runnable() {}
+private:
+  Runnable(const Runnable&) = delete;
+  Runnable& operator=(const Runnable&) = delete;
+  Runnable& operator=(const Runnable&&) = delete;
+};
+
+// This class is designed to be subclassed.
+class CancelableRunnable : public Runnable,
+                           public nsICancelableRunnable
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  // nsICancelableRunnable
+  virtual nsresult Cancel() override;
+
+  CancelableRunnable() {}
+
+protected:
+  virtual ~CancelableRunnable() {}
+private:
+  CancelableRunnable(const CancelableRunnable&) = delete;
+  CancelableRunnable& operator=(const CancelableRunnable&) = delete;
+  CancelableRunnable& operator=(const CancelableRunnable&&) = delete;
+};
+
+// This class is designed to be subclassed.
+class IncrementalRunnable : public CancelableRunnable,
+                            public nsIIncrementalRunnable
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  // nsIIncrementalRunnable
+  virtual void SetDeadline(TimeStamp aDeadline) override;
+
+  IncrementalRunnable() {}
+
+protected:
+  virtual ~IncrementalRunnable() {}
+private:
+  IncrementalRunnable(const IncrementalRunnable&) = delete;
+  IncrementalRunnable& operator=(const IncrementalRunnable&) = delete;
+  IncrementalRunnable& operator=(const IncrementalRunnable&&) = delete;
+};
+
+namespace detail {
+
+// An event that can be used to call a C++11 functions or function objects,
+// including lambdas. The function must have no required arguments, and must
+// return void.
+template<typename StoredFunction>
+class RunnableFunction : public Runnable
+{
+public:
+  template <typename F>
+  explicit RunnableFunction(F&& aFunction)
+    : mFunction(Forward<F>(aFunction))
+  { }
+
+  NS_IMETHOD Run() override {
+    static_assert(IsVoid<decltype(mFunction())>::value,
+                  "The lambda must return void!");
+    mFunction();
+    return NS_OK;
+  }
+private:
+  StoredFunction mFunction;
+};
+
+} // namespace detail
+
+} // namespace mozilla
+
+template<typename Function>
+already_AddRefed<mozilla::Runnable>
+NS_NewRunnableFunction(Function&& aFunction)
+{
+  return do_AddRef(new mozilla::detail::RunnableFunction
+                   // Make sure we store a non-reference in nsRunnableFunction.
+                   <typename mozilla::RemoveReference<Function>::Type>
+                   // But still forward aFunction to move if possible.
+                   (mozilla::Forward<Function>(aFunction)));
+}
+
+// An event that can be used to call a method on a class.  The class type must
+// support reference counting. This event supports Revoke for use
+// with nsRevocableEventPtr.
+template<class ClassType,
+         typename ReturnType = void,
+         bool Owning = true,
+         bool Cancelable = false>
+class nsRunnableMethod : public mozilla::Conditional<!Cancelable,
+                                                     mozilla::Runnable,
+                                                     mozilla::CancelableRunnable>::Type
+{
+public:
+  virtual void Revoke() = 0;
+
+  // These ReturnTypeEnforcer classes set up a blacklist for return types that
+  // we know are not safe. The default ReturnTypeEnforcer compiles just fine but
+  // already_AddRefed will not.
+  template<typename OtherReturnType>
+  class ReturnTypeEnforcer
+  {
+  public:
+    typedef int ReturnTypeIsSafe;
+  };
+
+  template<class T>
+  class ReturnTypeEnforcer<already_AddRefed<T>>
+  {
+    // No ReturnTypeIsSafe makes this illegal!
+  };
+
+  // Make sure this return type is safe.
+  typedef typename ReturnTypeEnforcer<ReturnType>::ReturnTypeIsSafe check;
+};
+
+template<class ClassType, bool Owning>
+struct nsRunnableMethodReceiver
+{
+  RefPtr<ClassType> mObj;
+  explicit nsRunnableMethodReceiver(ClassType* aObj) : mObj(aObj) {}
+  ~nsRunnableMethodReceiver() { Revoke(); }
+  ClassType* Get() const { return mObj.get(); }
+  void Revoke() { mObj = nullptr; }
+};
+
+template<class ClassType>
+struct nsRunnableMethodReceiver<ClassType, false>
+{
+  ClassType* MOZ_NON_OWNING_REF mObj;
+  explicit nsRunnableMethodReceiver(ClassType* aObj) : mObj(aObj) {}
+  ClassType* Get() const { return mObj; }
+  void Revoke() { mObj = nullptr; }
+};
+
+template<typename Method, bool Owning, bool Cancelable> struct nsRunnableMethodTraits;
+
+template<class C, typename R, bool Owning, bool Cancelable, typename... As>
+struct nsRunnableMethodTraits<R(C::*)(As...), Owning, Cancelable>
+{
+  typedef C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+
+template<class C, typename R, bool Owning, bool Cancelable, typename... As>
+struct nsRunnableMethodTraits<R(C::*)(As...) const, Owning, Cancelable>
+{
+  typedef const C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+
+#ifdef NS_HAVE_STDCALL
+template<class C, typename R, bool Owning, bool Cancelable, typename... As>
+struct nsRunnableMethodTraits<R(__stdcall C::*)(As...), Owning, Cancelable>
+{
+  typedef C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+
+template<class C, typename R, bool Owning, bool Cancelable>
+struct nsRunnableMethodTraits<R(NS_STDCALL C::*)(), Owning, Cancelable>
+{
+  typedef C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+template<class C, typename R, bool Owning, bool Cancelable, typename... As>
+struct nsRunnableMethodTraits<R(__stdcall C::*)(As...) const, Owning, Cancelable>
+{
+  typedef const C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+
+template<class C, typename R, bool Owning, bool Cancelable>
+struct nsRunnableMethodTraits<R(NS_STDCALL C::*)() const, Owning, Cancelable>
+{
+  typedef const C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+#endif
+
+
+// IsParameterStorageClass<T>::value is true if T is a parameter-storage class
+// that will be recognized by NS_New[NonOwning]RunnableMethodWithArg[s] to
+// force a specific storage&passing strategy (instead of inferring one,
+// see ParameterStorage).
+// When creating a new storage class, add a specialization for it to be
+// recognized.
+template<typename T>
+struct IsParameterStorageClass : public mozilla::FalseType {};
+
+// StoreXPassByY structs used to inform nsRunnableMethodArguments how to
+// store arguments, and how to pass them to the target method.
+
+template<typename T>
+struct StoreCopyPassByValue
+{
+  typedef T stored_type;
+  typedef T passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByValue(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByValue<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreCopyPassByConstLRef
+{
+  typedef T stored_type;
+  typedef const T& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByConstLRef(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByConstLRef<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreCopyPassByLRef
+{
+  typedef T stored_type;
+  typedef T& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByLRef(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByLRef<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreCopyPassByRRef
+{
+  typedef T stored_type;
+  typedef T&& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByRRef(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return mozilla::Move(m); }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByRRef<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreRefPassByLRef
+{
+  typedef T& stored_type;
+  typedef T& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreRefPassByLRef(A& a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreRefPassByLRef<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreConstRefPassByConstLRef
+{
+  typedef const T& stored_type;
+  typedef const T& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreConstRefPassByConstLRef(const A& a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreConstRefPassByConstLRef<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StorensRefPtrPassByPtr
+{
+  typedef RefPtr<T> stored_type;
+  typedef T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StorensRefPtrPassByPtr(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return m.get(); }
+};
+template<typename S>
+struct IsParameterStorageClass<StorensRefPtrPassByPtr<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StorePtrPassByPtr
+{
+  typedef T* stored_type;
+  typedef T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StorePtrPassByPtr(A a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StorePtrPassByPtr<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreConstPtrPassByConstPtr
+{
+  typedef const T* stored_type;
+  typedef const T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreConstPtrPassByConstPtr(A a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreConstPtrPassByConstPtr<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreCopyPassByConstPtr
+{
+  typedef T stored_type;
+  typedef const T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByConstPtr(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return &m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByConstPtr<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreCopyPassByPtr
+{
+  typedef T stored_type;
+  typedef T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByPtr(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return &m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByPtr<S>>
+  : public mozilla::TrueType {};
+
+namespace detail {
+
+template<typename TWithoutPointer>
+struct NonnsISupportsPointerStorageClass
+  : mozilla::Conditional<mozilla::IsConst<TWithoutPointer>::value,
+                         StoreConstPtrPassByConstPtr<
+                           typename mozilla::RemoveConst<TWithoutPointer>::Type>,
+                         StorePtrPassByPtr<TWithoutPointer>>
+{};
+
+template<typename>
+struct SFINAE1True : mozilla::TrueType
+{};
+
+template<class T>
+static auto HasRefCountMethodsTest(int)
+    -> SFINAE1True<decltype(mozilla::DeclVal<T>().AddRef(),
+                            mozilla::DeclVal<T>().Release())>;
+template<class>
+static auto HasRefCountMethodsTest(long) -> mozilla::FalseType;
+
+template<class T>
+struct HasRefCountMethods : decltype(HasRefCountMethodsTest<T>(0))
+{};
+
+template<typename T>
+struct IsRefcountedSmartPointer : public mozilla::FalseType
+{};
+
+template<typename T>
+struct IsRefcountedSmartPointer<RefPtr<T>> : public mozilla::TrueType
+{};
+
+template<typename T>
+struct IsRefcountedSmartPointer<nsCOMPtr<T>> : public mozilla::TrueType
+{};
+
+template<typename T>
+struct StripSmartPointer
+{
+  typedef void Type;
+};
+
+template<typename T>
+struct StripSmartPointer<RefPtr<T>>
+{
+  typedef T Type;
+};
+
+template<typename T>
+struct StripSmartPointer<nsCOMPtr<T>>
+{
+  typedef T Type;
+};
+
+template<typename TWithoutPointer>
+struct PointerStorageClass
+  : mozilla::Conditional<HasRefCountMethods<TWithoutPointer>::value,
+                         StorensRefPtrPassByPtr<TWithoutPointer>,
+                         typename NonnsISupportsPointerStorageClass<
+                           TWithoutPointer
+                         >::Type>
+{};
+
+template<typename TWithoutRef>
+struct LValueReferenceStorageClass
+  : mozilla::Conditional<mozilla::IsConst<TWithoutRef>::value,
+                         StoreConstRefPassByConstLRef<
+                           typename mozilla::RemoveConst<TWithoutRef>::Type>,
+                         StoreRefPassByLRef<TWithoutRef>>
+{};
+
+template<typename T>
+struct SmartPointerStorageClass
+  : mozilla::Conditional<IsRefcountedSmartPointer<T>::value,
+                         StorensRefPtrPassByPtr<
+                           typename StripSmartPointer<T>::Type>,
+                         StoreCopyPassByValue<T>>
+{};
+
+template<typename T>
+struct NonLValueReferenceStorageClass
+  : mozilla::Conditional<mozilla::IsRvalueReference<T>::value,
+                         StoreCopyPassByRRef<
+                           typename mozilla::RemoveReference<T>::Type>,
+                         typename SmartPointerStorageClass<T>::Type>
+{};
+
+template<typename T>
+struct NonPointerStorageClass
+  : mozilla::Conditional<mozilla::IsLvalueReference<T>::value,
+                         typename LValueReferenceStorageClass<
+                           typename mozilla::RemoveReference<T>::Type
+                         >::Type,
+                         typename NonLValueReferenceStorageClass<T>::Type>
+{};
+
+template<typename T>
+struct NonParameterStorageClass
+  : mozilla::Conditional<mozilla::IsPointer<T>::value,
+                         typename PointerStorageClass<
+                           typename mozilla::RemovePointer<T>::Type
+                         >::Type,
+                         typename NonPointerStorageClass<T>::Type>
+{};
+
+// Choose storage&passing strategy based on preferred storage type:
+// - If IsParameterStorageClass<T>::value is true, use as-is.
+// - RC*       -> StorensRefPtrPassByPtr<RC>     : Store RefPtr<RC>, pass RC*
+//   ^^ RC quacks like a ref-counted type (i.e., has AddRef and Release methods)
+// - const T*  -> StoreConstPtrPassByConstPtr<T> : Store const T*, pass const T*
+// - T*        -> StorePtrPassByPtr<T>           : Store T*, pass T*.
+// - const T&  -> StoreConstRefPassByConstLRef<T>: Store const T&, pass const T&.
+// - T&        -> StoreRefPassByLRef<T>          : Store T&, pass T&.
+// - T&&       -> StoreCopyPassByRRef<T>         : Store T, pass Move(T).
+// - RefPtr<T>, nsCOMPtr<T>
+//             -> StorensRefPtrPassByPtr<T>      : Store RefPtr<T>, pass T*
+// - Other T   -> StoreCopyPassByValue<T>        : Store T, pass T.
+// Other available explicit options:
+// -              StoreCopyPassByConstLRef<T>    : Store T, pass const T&.
+// -              StoreCopyPassByLRef<T>         : Store T, pass T& (of copy!)
+// -              StoreCopyPassByConstPtr<T>     : Store T, pass const T*
+// -              StoreCopyPassByPtr<T>          : Store T, pass T* (of copy!)
+// Or create your own class with PassAsParameter() method, optional
+// clean-up in destructor, and with associated IsParameterStorageClass<>.
+template<typename T>
+struct ParameterStorage
+  : mozilla::Conditional<IsParameterStorageClass<T>::value,
+                         T,
+                         typename NonParameterStorageClass<T>::Type>
+{};
+
+} /* namespace detail */
+
+namespace mozilla {
+
+namespace detail {
+
+// struct used to store arguments and later apply them to a method.
+template <typename... Ts>
+struct RunnableMethodArguments final
+{
+  Tuple<typename ::detail::ParameterStorage<Ts>::Type...> mArguments;
+  template <typename... As>
+  explicit RunnableMethodArguments(As&&... aArguments)
+    : mArguments(Forward<As>(aArguments)...)
+  {}
+  template<typename C, typename M, typename... Args, size_t... Indices>
+  static auto
+  applyImpl(C* o, M m, Tuple<Args...>& args, IndexSequence<Indices...>)
+      -> decltype(((*o).*m)(Get<Indices>(args).PassAsParameter()...))
+  {
+    return ((*o).*m)(Get<Indices>(args).PassAsParameter()...);
+  }
+  template<class C, typename M> auto apply(C* o, M m)
+      -> decltype(applyImpl(o, m, mArguments,
+                  typename IndexSequenceFor<Ts...>::Type()))
+  {
+    return applyImpl(o, m, mArguments,
+        typename IndexSequenceFor<Ts...>::Type());
+  }
+};
+
+template<typename Method, bool Owning, bool Cancelable, typename... Storages>
+class RunnableMethodImpl final
+  : public ::nsRunnableMethodTraits<Method, Owning, Cancelable>::base_type
+{
+  typedef typename ::nsRunnableMethodTraits<Method, Owning, Cancelable>::class_type
+      ClassType;
+  ::nsRunnableMethodReceiver<ClassType, Owning> mReceiver;
+  Method mMethod;
+  RunnableMethodArguments<Storages...> mArgs;
+private:
+  virtual ~RunnableMethodImpl() { Revoke(); };
+public:
+  template<typename... Args>
+  explicit RunnableMethodImpl(ClassType* aObj, Method aMethod,
+                              Args&&... aArgs)
+    : mReceiver(aObj)
+    , mMethod(aMethod)
+    , mArgs(Forward<Args>(aArgs)...)
+  {
+    static_assert(sizeof...(Storages) == sizeof...(Args), "Storages and Args should have equal sizes");
+  }
+  NS_IMETHOD Run()
+  {
+    if (MOZ_LIKELY(mReceiver.Get())) {
+      mArgs.apply(mReceiver.Get(), mMethod);
+    }
+    return NS_OK;
+  }
+  nsresult Cancel() {
+    static_assert(Cancelable, "Don't use me!");
+    Revoke();
+    return NS_OK;
+  }
+  void Revoke() { mReceiver.Revoke(); }
+};
+
+} // namespace detail
+
+// Use this template function like so:
+//
+//   nsCOMPtr<nsIRunnable> event =
+//     mozilla::NewRunnableMethod(myObject, &MyClass::HandleEvent);
+//   NS_DispatchToCurrentThread(event);
+//
+// Statically enforced constraints:
+//  - myObject must be of (or implicitly convertible to) type MyClass
+//  - MyClass must define AddRef and Release methods
+//
+
+template<typename PtrType, typename Method>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, true, false>::base_type>
+NewRunnableMethod(PtrType aPtr, Method aMethod)
+{
+  return do_AddRef(new detail::RunnableMethodImpl<Method, true, false>(aPtr, aMethod));
+}
+
+template<typename PtrType, typename Method>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, true, true>::base_type>
+NewCancelableRunnableMethod(PtrType aPtr, Method aMethod)
+{
+  return do_AddRef(new detail::RunnableMethodImpl<Method, true, true>(aPtr, aMethod));
+}
+
+template<typename PtrType, typename Method>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, false, false>::base_type>
+NewNonOwningRunnableMethod(PtrType&& aPtr, Method aMethod)
+{
+  return do_AddRef(new detail::RunnableMethodImpl<Method, false, false>(aPtr, aMethod));
+}
+
+template<typename PtrType, typename Method>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, false, true>::base_type>
+NewNonOwningCancelableRunnableMethod(PtrType&& aPtr, Method aMethod)
+{
+  return do_AddRef(new detail::RunnableMethodImpl<Method, false, true>(aPtr, aMethod));
+}
+
+// Similar to NewRunnableMethod. Call like so:
+// nsCOMPtr<nsIRunnable> event =
+//   NewRunnableMethod<Types,...>(myObject, &MyClass::HandleEvent, myArg1,...);
+// 'Types' are the stored type for each argument, see ParameterStorage for details.
+template<typename... Storages, typename Method, typename PtrType, typename... Args>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, true, false>::base_type>
+NewRunnableMethod(PtrType&& aPtr, Method aMethod, Args&&... aArgs)
+{
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(new detail::RunnableMethodImpl<Method, true, false, Storages...>(
+      aPtr, aMethod, mozilla::Forward<Args>(aArgs)...));
+}
+
+template<typename... Storages, typename Method, typename PtrType, typename... Args>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, false, false>::base_type>
+NewNonOwningRunnableMethod(PtrType&& aPtr, Method aMethod, Args&&... aArgs)
+{
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(new detail::RunnableMethodImpl<Method, false, false, Storages...>(
+      aPtr, aMethod, mozilla::Forward<Args>(aArgs)...));
+}
+
+template<typename... Storages, typename Method, typename PtrType, typename... Args>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, true, true>::base_type>
+NewCancelableRunnableMethod(PtrType&& aPtr, Method aMethod, Args&&... aArgs)
+{
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(new detail::RunnableMethodImpl<Method, true, true, Storages...>(
+      aPtr, aMethod, mozilla::Forward<Args>(aArgs)...));
+}
+
+template<typename... Storages, typename Method, typename PtrType, typename... Args>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, false, true>::base_type>
+NewNonOwningCancelableRunnableMethod(PtrType&& aPtr, Method aMethod,
+                                                Args&&... aArgs)
+{
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(new detail::RunnableMethodImpl<Method, false, true, Storages...>(
+      aPtr, aMethod, mozilla::Forward<Args>(aArgs)...));
+}
+
+} // namespace mozilla
+
+#endif  // XPCOM_GLUE_AVOID_NSPR
+
+// This class is designed to be used when you have an event class E that has a
+// pointer back to resource class R.  If R goes away while E is still pending,
+// then it is important to "revoke" E so that it does not try use R after R has
+// been destroyed.  nsRevocableEventPtr makes it easy for R to manage such
+// situations:
+//
+//   class R;
+//
+//   class E : public mozilla::Runnable {
+//   public:
+//     void Revoke() {
+//       mResource = nullptr;
+//     }
+//   private:
+//     R *mResource;
+//   };
+//
+//   class R {
+//   public:
+//     void EventHandled() {
+//       mEvent.Forget();
+//     }
+//   private:
+//     nsRevocableEventPtr<E> mEvent;
+//   };
+//
+//   void R::PostEvent() {
+//     // Make sure any pending event is revoked.
+//     mEvent->Revoke();
+//
+//     nsCOMPtr<nsIRunnable> event = new E();
+//     if (NS_SUCCEEDED(NS_DispatchToCurrentThread(event))) {
+//       // Keep pointer to event so we can revoke it.
+//       mEvent = event;
+//     }
+//   }
+//
+//   NS_IMETHODIMP E::Run() {
+//     if (!mResource)
+//       return NS_OK;
+//     ...
+//     mResource->EventHandled();
+//     return NS_OK;
+//   }
+//
+template<class T>
+class nsRevocableEventPtr
+{
+public:
+  nsRevocableEventPtr() : mEvent(nullptr) {}
+  ~nsRevocableEventPtr() { Revoke(); }
+
+  const nsRevocableEventPtr& operator=(T* aEvent)
+  {
+    if (mEvent != aEvent) {
+      Revoke();
+      mEvent = aEvent;
+    }
+    return *this;
+  }
+
+  const nsRevocableEventPtr& operator=(already_AddRefed<T> aEvent)
+  {
+    RefPtr<T> event = aEvent;
+    if (mEvent != event) {
+      Revoke();
+      mEvent = event.forget();
+    }
+    return *this;
+  }
+
+  void Revoke()
+  {
+    if (mEvent) {
+      mEvent->Revoke();
+      mEvent = nullptr;
+    }
+  }
+
+  void Forget() { mEvent = nullptr; }
+  bool IsPending() { return mEvent != nullptr; }
+  T* get() { return mEvent; }
+
+private:
+  // Not implemented
+  nsRevocableEventPtr(const nsRevocableEventPtr&);
+  nsRevocableEventPtr& operator=(const nsRevocableEventPtr&);
+
+  RefPtr<T> mEvent;
+};
+
+/**
+ * A simple helper to suffix thread pool name
+ * with incremental numbers.
+ */
+class nsThreadPoolNaming
+{
+public:
+  nsThreadPoolNaming() : mCounter(0) {}
+
+  /**
+   * Creates and sets next thread name as "<aPoolName> #<n>"
+   * on the specified thread.  If no thread is specified (aThread
+   * is null) then the name is synchronously set on the current thread.
+   */
+  void SetThreadPoolName(const nsACString& aPoolName,
+                         nsIThread* aThread = nullptr);
+
+private:
+  mozilla::Atomic<uint32_t> mCounter;
+
+  nsThreadPoolNaming(const nsThreadPoolNaming&) = delete;
+  void operator=(const nsThreadPoolNaming&) = delete;
+};
+
+/**
+ * Thread priority in most operating systems affect scheduling, not IO.  This
+ * helper is used to set the current thread to low IO priority for the lifetime
+ * of the created object.  You can only use this low priority IO setting within
+ * the context of the current thread.
+ */
+class MOZ_STACK_CLASS nsAutoLowPriorityIO
+{
+public:
+  nsAutoLowPriorityIO();
+  ~nsAutoLowPriorityIO();
+
+private:
+  bool lowIOPrioritySet;
+#if defined(XP_MACOSX)
+  int oldPriority;
+#endif
+};
+
+void
+NS_SetMainThread();
+
+#endif  // nsThreadUtils_h__
diff --git a/xpcom/glue/nsVersionComparator.cpp b/xpcom/glue/nsVersionComparator.cpp
new file mode 100644
index 0000000000..6be32b9744
--- /dev/null
+++ b/xpcom/glue/nsVersionComparator.cpp
@@ -0,0 +1,379 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsVersionComparator.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#if defined(XP_WIN) && !defined(UPDATER_NO_STRING_GLUE_STL)
+#include <wchar.h>
+#include "nsStringGlue.h"
+#endif
+
+struct VersionPart
+{
+  int32_t     numA;
+
+  const char* strB;    // NOT null-terminated, can be a null pointer
+  uint32_t    strBlen;
+
+  int32_t     numC;
+
+  char*       extraD;  // null-terminated
+};
+
+#ifdef XP_WIN
+struct VersionPartW
+{
+  int32_t     numA;
+
+  wchar_t*    strB;    // NOT null-terminated, can be a null pointer
+  uint32_t    strBlen;
+
+  int32_t     numC;
+
+  wchar_t*    extraD;  // null-terminated
+
+};
+#endif
+
+/**
+ * Parse a version part into a number and "extra text".
+ *
+ * @returns A pointer to the next versionpart, or null if none.
+ */
+static char*
+ParseVP(char* aPart, VersionPart& aResult)
+{
+  char* dot;
+
+  aResult.numA = 0;
+  aResult.strB = nullptr;
+  aResult.strBlen = 0;
+  aResult.numC = 0;
+  aResult.extraD = nullptr;
+
+  if (!aPart) {
+    return aPart;
+  }
+
+  dot = strchr(aPart, '.');
+  if (dot) {
+    *dot = '\0';
+  }
+
+  if (aPart[0] == '*' && aPart[1] == '\0') {
+    aResult.numA = INT32_MAX;
+    aResult.strB = "";
+  } else {
+    aResult.numA = strtol(aPart, const_cast<char**>(&aResult.strB), 10);
+  }
+
+  if (!*aResult.strB) {
+    aResult.strB = nullptr;
+    aResult.strBlen = 0;
+  } else {
+    if (aResult.strB[0] == '+') {
+      static const char kPre[] = "pre";
+
+      ++aResult.numA;
+      aResult.strB = kPre;
+      aResult.strBlen = sizeof(kPre) - 1;
+    } else {
+      const char* numstart = strpbrk(aResult.strB, "0123456789+-");
+      if (!numstart) {
+        aResult.strBlen = strlen(aResult.strB);
+      } else {
+        aResult.strBlen = numstart - aResult.strB;
+
+        aResult.numC = strtol(numstart, &aResult.extraD, 10);
+        if (!*aResult.extraD) {
+          aResult.extraD = nullptr;
+        }
+      }
+    }
+  }
+
+  if (dot) {
+    ++dot;
+
+    if (!*dot) {
+      dot = nullptr;
+    }
+  }
+
+  return dot;
+}
+
+
+/**
+ * Parse a version part into a number and "extra text".
+ *
+ * @returns A pointer to the next versionpart, or null if none.
+ */
+#ifdef XP_WIN
+static wchar_t*
+ParseVP(wchar_t* aPart, VersionPartW& aResult)
+{
+
+  wchar_t* dot;
+
+  aResult.numA = 0;
+  aResult.strB = nullptr;
+  aResult.strBlen = 0;
+  aResult.numC = 0;
+  aResult.extraD = nullptr;
+
+  if (!aPart) {
+    return aPart;
+  }
+
+  dot = wcschr(aPart, '.');
+  if (dot) {
+    *dot = '\0';
+  }
+
+  if (aPart[0] == '*' && aPart[1] == '\0') {
+    aResult.numA = INT32_MAX;
+    aResult.strB = L"";
+  } else {
+    aResult.numA = wcstol(aPart, const_cast<wchar_t**>(&aResult.strB), 10);
+  }
+
+  if (!*aResult.strB) {
+    aResult.strB = nullptr;
+    aResult.strBlen = 0;
+  } else {
+    if (aResult.strB[0] == '+') {
+      static wchar_t kPre[] = L"pre";
+
+      ++aResult.numA;
+      aResult.strB = kPre;
+      aResult.strBlen = sizeof(kPre) - 1;
+    } else {
+      const wchar_t* numstart = wcspbrk(aResult.strB, L"0123456789+-");
+      if (!numstart) {
+        aResult.strBlen = wcslen(aResult.strB);
+      } else {
+        aResult.strBlen = numstart - aResult.strB;
+
+        aResult.numC = wcstol(numstart, &aResult.extraD, 10);
+        if (!*aResult.extraD) {
+          aResult.extraD = nullptr;
+        }
+      }
+    }
+  }
+
+  if (dot) {
+    ++dot;
+
+    if (!*dot) {
+      dot = nullptr;
+    }
+  }
+
+  return dot;
+}
+#endif
+
+// compare two null-terminated strings, which may be null pointers
+static int32_t
+ns_strcmp(const char* aStr1, const char* aStr2)
+{
+  // any string is *before* no string
+  if (!aStr1) {
+    return aStr2 != 0;
+  }
+
+  if (!aStr2) {
+    return -1;
+  }
+
+  return strcmp(aStr1, aStr2);
+}
+
+// compare two length-specified string, which may be null pointers
+static int32_t
+ns_strnncmp(const char* aStr1, uint32_t aLen1,
+            const char* aStr2, uint32_t aLen2)
+{
+  // any string is *before* no string
+  if (!aStr1) {
+    return aStr2 != 0;
+  }
+
+  if (!aStr2) {
+    return -1;
+  }
+
+  for (; aLen1 && aLen2; --aLen1, --aLen2, ++aStr1, ++aStr2) {
+    if (*aStr1 < *aStr2) {
+      return -1;
+    }
+
+    if (*aStr1 > *aStr2) {
+      return 1;
+    }
+  }
+
+  if (aLen1 == 0) {
+    return aLen2 == 0 ? 0 : -1;
+  }
+
+  return 1;
+}
+
+// compare two int32_t
+static int32_t
+ns_cmp(int32_t aNum1, int32_t aNum2)
+{
+  if (aNum1 < aNum2) {
+    return -1;
+  }
+
+  return aNum1 != aNum2;
+}
+
+/**
+ * Compares two VersionParts
+ */
+static int32_t
+CompareVP(VersionPart& aVer1, VersionPart& aVer2)
+{
+  int32_t r = ns_cmp(aVer1.numA, aVer2.numA);
+  if (r) {
+    return r;
+  }
+
+  r = ns_strnncmp(aVer1.strB, aVer1.strBlen, aVer2.strB, aVer2.strBlen);
+  if (r) {
+    return r;
+  }
+
+  r = ns_cmp(aVer1.numC, aVer2.numC);
+  if (r) {
+    return r;
+  }
+
+  return ns_strcmp(aVer1.extraD, aVer2.extraD);
+}
+
+/**
+ * Compares two VersionParts
+ */
+#ifdef XP_WIN
+static int32_t
+CompareVP(VersionPartW& aVer1, VersionPartW& aVer2)
+{
+  int32_t r = ns_cmp(aVer1.numA, aVer2.numA);
+  if (r) {
+    return r;
+  }
+
+  r = wcsncmp(aVer1.strB, aVer2.strB, XPCOM_MIN(aVer1.strBlen, aVer2.strBlen));
+  if (r) {
+    return r;
+  }
+
+  r = ns_cmp(aVer1.numC, aVer2.numC);
+  if (r) {
+    return r;
+  }
+
+  if (!aVer1.extraD) {
+    return aVer2.extraD != 0;
+  }
+
+  if (!aVer2.extraD) {
+    return -1;
+  }
+
+  return wcscmp(aVer1.extraD, aVer2.extraD);
+}
+#endif
+
+namespace mozilla {
+
+#ifdef XP_WIN
+int32_t
+CompareVersions(const char16_t* aStrA, const char16_t* aStrB)
+{
+  wchar_t* A2 = wcsdup(char16ptr_t(aStrA));
+  if (!A2) {
+    return 1;
+  }
+
+  wchar_t* B2 = wcsdup(char16ptr_t(aStrB));
+  if (!B2) {
+    free(A2);
+    return 1;
+  }
+
+  int32_t result;
+  wchar_t* a = A2;
+  wchar_t* b = B2;
+
+  do {
+    VersionPartW va, vb;
+
+    a = ParseVP(a, va);
+    b = ParseVP(b, vb);
+
+    result = CompareVP(va, vb);
+    if (result) {
+      break;
+    }
+
+  } while (a || b);
+
+  free(A2);
+  free(B2);
+
+  return result;
+}
+#endif
+
+int32_t
+CompareVersions(const char* aStrA, const char* aStrB)
+{
+  char* A2 = strdup(aStrA);
+  if (!A2) {
+    return 1;
+  }
+
+  char* B2 = strdup(aStrB);
+  if (!B2) {
+    free(A2);
+    return 1;
+  }
+
+  int32_t result;
+  char* a = A2;
+  char* b = B2;
+
+  do {
+    VersionPart va, vb;
+
+    a = ParseVP(a, va);
+    b = ParseVP(b, vb);
+
+    result = CompareVP(va, vb);
+    if (result) {
+      break;
+    }
+
+  } while (a || b);
+
+  free(A2);
+  free(B2);
+
+  return result;
+}
+
+} // namespace mozilla
+
diff --git a/xpcom/glue/nsVersionComparator.h b/xpcom/glue/nsVersionComparator.h
new file mode 100644
index 0000000000..0dbf8532b0
--- /dev/null
+++ b/xpcom/glue/nsVersionComparator.h
@@ -0,0 +1,174 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsVersionComparator_h__
+#define nsVersionComparator_h__
+
+#include "nscore.h"
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#if defined(XP_WIN) && !defined(UPDATER_NO_STRING_GLUE_STL)
+#include <wchar.h>
+#include "nsStringGlue.h"
+#endif
+
+/**
+ * In order to compare version numbers in Mozilla, you need to use the
+ * mozilla::Version class.  You can construct an object of this type by passing
+ * in a string version number to the constructor.  Objects of this type can be
+ * compared using the standard comparison operators.
+ *
+ * For example, let's say that you want to make sure that a given version
+ * number is not older than 15.a2.  Here's how you would write a function to
+ * do that.
+ *
+ * bool IsVersionValid(const char* version) {
+ *   return mozilla::Version("15.a2") <= mozilla::Version(version);
+ * }
+ *
+ * Or, since Version's constructor is implicit, you can simplify this code:
+ *
+ * bool IsVersionValid(const char* version) {
+ *   return mozilla::Version("15.a2") <= version;
+ * }
+ *
+ * On Windows, if your version strings are wide characters, you should use the
+ * mozilla::VersionW variant instead.  The semantics of that class is the same
+ * as Version.
+ */
+
+namespace mozilla {
+
+int32_t CompareVersions(const char* aStrA, const char* aStrB);
+
+#ifdef XP_WIN
+int32_t CompareVersions(const char16_t* aStrA, const char16_t* aStrB);
+#endif
+
+struct Version
+{
+  explicit Version(const char* aVersionString)
+  {
+    versionContent = strdup(aVersionString);
+  }
+
+  const char* ReadContent() const
+  {
+    return versionContent;
+  }
+
+  ~Version()
+  {
+    free(versionContent);
+  }
+
+  bool operator<(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) == -1;
+  }
+  bool operator<=(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) < 1;
+  }
+  bool operator>(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) == 1;
+  }
+  bool operator>=(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) > -1;
+  }
+  bool operator==(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) == 0;
+  }
+  bool operator!=(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) != 0;
+  }
+  bool operator<(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) == -1;
+  }
+  bool operator<=(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) < 1;
+  }
+  bool operator>(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) == 1;
+  }
+  bool operator>=(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) > -1;
+  }
+  bool operator==(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) == 0;
+  }
+  bool operator!=(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) != 0;
+  }
+
+private:
+  char* versionContent;
+};
+
+#ifdef XP_WIN
+struct VersionW
+{
+  VersionW(const char16_t* aVersionStringW)
+  {
+    versionContentW =
+      reinterpret_cast<char16_t*>(wcsdup(char16ptr_t(aVersionStringW)));
+  }
+
+  const char16_t* ReadContentW() const
+  {
+    return versionContentW;
+  }
+
+  ~VersionW()
+  {
+    free(versionContentW);
+  }
+
+  bool operator<(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) == -1;
+  }
+  bool operator<=(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) < 1;
+  }
+  bool operator>(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) == 1;
+  }
+  bool operator>=(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) > -1;
+  }
+  bool operator==(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) == 0;
+  }
+  bool operator!=(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) != 0;
+  }
+
+private:
+  char16_t* versionContentW;
+};
+#endif
+
+} // namespace mozilla
+
+#endif // nsVersionComparator_h__
+
diff --git a/xpcom/glue/nsWeakReference.cpp b/xpcom/glue/nsWeakReference.cpp
new file mode 100644
index 0000000000..57f372641e
--- /dev/null
+++ b/xpcom/glue/nsWeakReference.cpp
@@ -0,0 +1,164 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// nsWeakReference.cpp
+
+#include "mozilla/Attributes.h"
+
+#include "nsWeakReference.h"
+#include "nsCOMPtr.h"
+#include "nsDebug.h"
+
+#ifdef MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED
+
+#define MOZ_WEAKREF_DECL_OWNINGTHREAD nsAutoOwningThread _mWeakRefOwningThread;
+#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD \
+  NS_CheckThreadSafe(_mWeakRefOwningThread.GetThread(), "nsWeakReference not thread-safe")
+#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(that) \
+  NS_CheckThreadSafe((that)->_mWeakRefOwningThread.GetThread(), "nsWeakReference not thread-safe")
+
+#else
+
+#define MOZ_WEAKREF_DECL_OWNINGTHREAD
+#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD do { } while (false)
+#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(that) do { } while (false)
+
+#endif
+
+class nsWeakReference final : public nsIWeakReference
+{
+public:
+  // nsISupports...
+  NS_DECL_ISUPPORTS
+
+  // nsIWeakReference...
+  NS_DECL_NSIWEAKREFERENCE
+  virtual size_t SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const override;
+
+private:
+  MOZ_WEAKREF_DECL_OWNINGTHREAD
+
+  friend class nsSupportsWeakReference;
+
+  explicit nsWeakReference(nsSupportsWeakReference* aReferent)
+    : mReferent(aReferent)
+    // ...I can only be constructed by an |nsSupportsWeakReference|
+  {
+  }
+
+  ~nsWeakReference()
+  // ...I will only be destroyed by calling |delete| myself.
+  {
+    MOZ_WEAKREF_ASSERT_OWNINGTHREAD;
+    if (mReferent) {
+      mReferent->NoticeProxyDestruction();
+    }
+  }
+
+  void
+  NoticeReferentDestruction()
+  // ...called (only) by an |nsSupportsWeakReference| from _its_ dtor.
+  {
+    MOZ_WEAKREF_ASSERT_OWNINGTHREAD;
+    mReferent = nullptr;
+  }
+
+  nsSupportsWeakReference* MOZ_NON_OWNING_REF mReferent;
+};
+
+nsresult
+nsQueryReferent::operator()(const nsIID& aIID, void** aAnswer) const
+{
+  nsresult status;
+  if (mWeakPtr) {
+    if (NS_FAILED(status = mWeakPtr->QueryReferent(aIID, aAnswer))) {
+      *aAnswer = 0;
+    }
+  } else {
+    status = NS_ERROR_NULL_POINTER;
+  }
+
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+nsIWeakReference*  // or else |already_AddRefed<nsIWeakReference>|
+NS_GetWeakReference(nsISupports* aInstancePtr, nsresult* aErrorPtr)
+{
+  nsresult status;
+
+  nsIWeakReference* result = nullptr;
+
+  if (aInstancePtr) {
+    nsCOMPtr<nsISupportsWeakReference> factoryPtr =
+      do_QueryInterface(aInstancePtr, &status);
+    if (factoryPtr) {
+      status = factoryPtr->GetWeakReference(&result);
+    }
+    // else, |status| has already been set by |do_QueryInterface|
+  } else {
+    status = NS_ERROR_NULL_POINTER;
+  }
+
+  if (aErrorPtr) {
+    *aErrorPtr = status;
+  }
+  return result;
+}
+
+nsresult
+nsSupportsWeakReference::GetWeakReference(nsIWeakReference** aInstancePtr)
+{
+  if (!aInstancePtr) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (!mProxy) {
+    mProxy = new nsWeakReference(this);
+  } else {
+    MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(mProxy);
+  }
+  *aInstancePtr = mProxy;
+
+  nsresult status;
+  if (!*aInstancePtr) {
+    status = NS_ERROR_OUT_OF_MEMORY;
+  } else {
+    NS_ADDREF(*aInstancePtr);
+    status = NS_OK;
+  }
+
+  return status;
+}
+
+NS_IMPL_ISUPPORTS(nsWeakReference, nsIWeakReference)
+
+NS_IMETHODIMP
+nsWeakReference::QueryReferent(const nsIID& aIID, void** aInstancePtr)
+{
+  MOZ_WEAKREF_ASSERT_OWNINGTHREAD;
+
+  return mReferent ? mReferent->QueryInterface(aIID, aInstancePtr) :
+                     NS_ERROR_NULL_POINTER;
+}
+
+size_t
+nsWeakReference::SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this);
+}
+
+void
+nsSupportsWeakReference::ClearWeakReferences()
+{
+  if (mProxy) {
+    mProxy->NoticeReferentDestruction();
+    mProxy = nullptr;
+  }
+}
+
diff --git a/xpcom/glue/nsWeakReference.h b/xpcom/glue/nsWeakReference.h
new file mode 100644
index 0000000000..fc875ba968
--- /dev/null
+++ b/xpcom/glue/nsWeakReference.h
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsWeakReference_h__
+#define nsWeakReference_h__
+
+// nsWeakReference.h
+
+// See mfbt/WeakPtr.h for a more typesafe C++ implementation of weak references
+
+#include "nsIWeakReferenceUtils.h"
+
+class nsWeakReference;
+
+class nsSupportsWeakReference : public nsISupportsWeakReference
+{
+public:
+  nsSupportsWeakReference() : mProxy(0) {}
+
+  NS_DECL_NSISUPPORTSWEAKREFERENCE
+
+protected:
+  inline ~nsSupportsWeakReference();
+
+private:
+  friend class nsWeakReference;
+
+  // Called (only) by an |nsWeakReference| from _its_ dtor.
+  // The thread safety check is made by the caller.
+  void NoticeProxyDestruction() { mProxy = nullptr; }
+
+  nsWeakReference* MOZ_NON_OWNING_REF mProxy;
+
+protected:
+
+  void ClearWeakReferences();
+  bool HasWeakReferences() const { return !!mProxy; }
+};
+
+inline
+nsSupportsWeakReference::~nsSupportsWeakReference()
+{
+  ClearWeakReferences();
+}
+
+#endif
diff --git a/xpcom/glue/nsXPTCUtils.h b/xpcom/glue/nsXPTCUtils.h
new file mode 100644
index 0000000000..8922aca162
--- /dev/null
+++ b/xpcom/glue/nsXPTCUtils.h
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPTCUtils_h__
+#define nsXPTCUtils_h__
+
+#include "xptcall.h"
+#include "mozilla/MemoryReporting.h"
+
+/**
+ * A helper class that initializes an xptcall helper at construction
+ * and releases it at destruction.
+ */
+class nsAutoXPTCStub : protected nsIXPTCProxy
+{
+public:
+  nsISomeInterface* mXPTCStub;
+
+protected:
+  nsAutoXPTCStub() : mXPTCStub(nullptr) {}
+
+  nsresult
+  InitStub(const nsIID& aIID)
+  {
+    return NS_GetXPTCallStub(aIID, this, &mXPTCStub);
+  }
+
+  ~nsAutoXPTCStub()
+  {
+    if (mXPTCStub) {
+      NS_DestroyXPTCallStub(mXPTCStub);
+    }
+  }
+
+  size_t
+  SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return mXPTCStub ? NS_SizeOfIncludingThisXPTCallStub(mXPTCStub, aMallocSizeOf) : 0;
+  }
+};
+
+#endif // nsXPTCUtils_h__
diff --git a/xpcom/glue/objs.mozbuild b/xpcom/glue/objs.mozbuild
new file mode 100644
index 0000000000..8161e1ebce
--- /dev/null
+++ b/xpcom/glue/objs.mozbuild
@@ -0,0 +1,48 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+xpcom_glue_src_lcppsrcs = [
+    'AppData.cpp',
+    'FileUtils.cpp',
+    'nsArrayEnumerator.cpp',
+    'nsArrayUtils.cpp',
+    'nsCategoryCache.cpp',
+    'nsClassInfoImpl.cpp',
+    'nsCOMArray.cpp',
+    'nsComponentManagerUtils.cpp',
+    'nsCOMPtr.cpp',
+    'nsCRTGlue.cpp',
+    'nsCycleCollectionParticipant.cpp',
+    'nsDeque.cpp',
+    'nsEnumeratorUtils.cpp',
+    'nsID.cpp',
+    'nsIInterfaceRequestorUtils.cpp',
+    'nsINIParser.cpp',
+    'nsISupportsImpl.cpp',
+    'nsMemory.cpp',
+    'nsQuickSort.cpp',
+    'nsTArray.cpp',
+    'nsThreadUtils.cpp',
+    'nsTObserverArray.cpp',
+    'nsVersionComparator.cpp',
+    'nsWeakReference.cpp',
+    'PLDHashTable.cpp',
+]
+
+xpcom_glue_src_cppsrcs = [
+    '/xpcom/glue/%s' % s for s in xpcom_glue_src_lcppsrcs
+]
+
+xpcom_gluens_src_lcppsrcs = [
+    'BlockingResourceBase.cpp',
+    'GenericFactory.cpp',
+    'nsProxyRelease.cpp',
+    'nsTextFormatter.cpp',
+]
+
+xpcom_gluens_src_cppsrcs = [
+    '/xpcom/glue/%s' % s for s in xpcom_gluens_src_lcppsrcs
+]
diff --git a/xpcom/glue/standalone/moz.build b/xpcom/glue/standalone/moz.build
new file mode 100644
index 0000000000..fd91fa0bb0
--- /dev/null
+++ b/xpcom/glue/standalone/moz.build
@@ -0,0 +1,58 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# On win we build two glue libs - glue linked to crt dlls here and in staticruntime we build
+# a statically linked glue lib.
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DIRS += ['staticruntime']
+
+include('../objs.mozbuild')
+
+SOURCES += xpcom_glue_src_cppsrcs
+
+SOURCES += [
+    '../nsStringAPI.cpp',
+    'nsXPCOMGlue.cpp',
+]
+
+Library('xpcomglue')
+
+EXPORTS += [
+    'nsXPCOMGlue.h',
+]
+
+SDK_LIBRARY = True
+
+FORCE_STATIC_LIB = True
+
+if CONFIG['_MSC_VER']:
+    DEFINES['_USE_ANSI_CPP'] = True
+    # Don't include directives about which CRT to use
+    CFLAGS += ['-Zl']
+    CXXFLAGS += ['-Zl']
+
+DEFINES['XPCOM_GLUE'] = True
+
+LOCAL_INCLUDES += [
+    '../../build',
+    '../../threads',
+]
+
+# Don't use STL wrappers here (i.e. wrapped <new>); they require mozalloc
+DISABLE_STL_WRAPPING = True
+
+# Include fallible for third party code using the xpcom glue
+USE_LIBS += [
+    'fallible',
+]
+
+# Force to build a static library only
+NO_EXPAND_LIBS = True
+
+DIST_INSTALL = True
+
+if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('gtk2', 'gtk3'):
+    CXXFLAGS += CONFIG['GLIB_CFLAGS']
diff --git a/xpcom/glue/standalone/nsXPCOMGlue.cpp b/xpcom/glue/standalone/nsXPCOMGlue.cpp
new file mode 100644
index 0000000000..b657d7050e
--- /dev/null
+++ b/xpcom/glue/standalone/nsXPCOMGlue.cpp
@@ -0,0 +1,927 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsXPCOMGlue.h"
+
+#include "nspr.h"
+#include "nsDebug.h"
+#include "nsIServiceManager.h"
+#include "nsXPCOMPrivate.h"
+#include "nsCOMPtr.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "mozilla/FileUtils.h"
+#include "mozilla/Sprintf.h"
+
+using namespace mozilla;
+
+#define XPCOM_DEPENDENT_LIBS_LIST "dependentlibs.list"
+
+static XPCOMFunctions xpcomFunctions;
+static bool do_preload = false;
+
+#if defined(XP_WIN)
+#define READ_TEXTMODE L"rt"
+#else
+#define READ_TEXTMODE "r"
+#endif
+
+#if defined(XP_WIN)
+#include <windows.h>
+#include <mbstring.h>
+
+typedef HINSTANCE LibHandleType;
+
+static LibHandleType
+GetLibHandle(pathstr_t aDependentLib)
+{
+  LibHandleType libHandle =
+    LoadLibraryExW(aDependentLib, nullptr, LOAD_WITH_ALTERED_SEARCH_PATH);
+
+#ifdef DEBUG
+  if (!libHandle) {
+    DWORD err = GetLastError();
+    LPWSTR lpMsgBuf;
+    FormatMessageW(
+      FORMAT_MESSAGE_ALLOCATE_BUFFER |
+      FORMAT_MESSAGE_FROM_SYSTEM |
+      FORMAT_MESSAGE_IGNORE_INSERTS,
+      nullptr,
+      err,
+      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+      (LPWSTR)&lpMsgBuf,
+      0,
+      nullptr
+    );
+    wprintf(L"Error loading %ls: %s\n", aDependentLib, lpMsgBuf);
+    LocalFree(lpMsgBuf);
+  }
+#endif
+
+  return libHandle;
+}
+
+static NSFuncPtr
+GetSymbol(LibHandleType aLibHandle, const char* aSymbol)
+{
+  return (NSFuncPtr)GetProcAddress(aLibHandle, aSymbol);
+}
+
+static void
+CloseLibHandle(LibHandleType aLibHandle)
+{
+  FreeLibrary(aLibHandle);
+}
+
+#else
+#include <dlfcn.h>
+
+#if defined(MOZ_LINKER) && !defined(ANDROID)
+extern "C" {
+NS_HIDDEN __typeof(dlopen) __wrap_dlopen;
+NS_HIDDEN __typeof(dlsym) __wrap_dlsym;
+NS_HIDDEN __typeof(dlclose) __wrap_dlclose;
+}
+
+#define dlopen __wrap_dlopen
+#define dlsym __wrap_dlsym
+#define dlclose __wrap_dlclose
+#endif
+
+typedef void* LibHandleType;
+
+static LibHandleType
+GetLibHandle(pathstr_t aDependentLib)
+{
+  LibHandleType libHandle = dlopen(aDependentLib,
+                                   RTLD_GLOBAL | RTLD_LAZY
+#ifdef XP_MACOSX
+                                   | RTLD_FIRST
+#endif
+                                   );
+  if (!libHandle) {
+    fprintf(stderr, "XPCOMGlueLoad error for file %s:\n%s\n", aDependentLib,
+            dlerror());
+  }
+  return libHandle;
+}
+
+static NSFuncPtr
+GetSymbol(LibHandleType aLibHandle, const char* aSymbol)
+{
+  return (NSFuncPtr)dlsym(aLibHandle, aSymbol);
+}
+
+static void
+CloseLibHandle(LibHandleType aLibHandle)
+{
+  dlclose(aLibHandle);
+}
+#endif
+
+struct DependentLib
+{
+  LibHandleType libHandle;
+  DependentLib* next;
+};
+
+static DependentLib* sTop;
+
+static void
+AppendDependentLib(LibHandleType aLibHandle)
+{
+  DependentLib* d = new DependentLib;
+  if (!d) {
+    return;
+  }
+
+  d->next = sTop;
+  d->libHandle = aLibHandle;
+
+  sTop = d;
+}
+
+static bool
+ReadDependentCB(pathstr_t aDependentLib, bool aDoPreload)
+{
+  if (aDoPreload) {
+    ReadAheadLib(aDependentLib);
+  }
+  LibHandleType libHandle = GetLibHandle(aDependentLib);
+  if (libHandle) {
+    AppendDependentLib(libHandle);
+  }
+
+  return libHandle;
+}
+
+#ifdef XP_WIN
+static bool
+ReadDependentCB(const char* aDependentLib, bool do_preload)
+{
+  wchar_t wideDependentLib[MAX_PATH];
+  MultiByteToWideChar(CP_UTF8, 0, aDependentLib, -1, wideDependentLib, MAX_PATH);
+  return ReadDependentCB(wideDependentLib, do_preload);
+}
+
+inline FILE*
+TS_tfopen(const char* path, const wchar_t* mode)
+{
+  wchar_t wPath[MAX_PATH];
+  MultiByteToWideChar(CP_UTF8, 0, path, -1, wPath, MAX_PATH);
+  return _wfopen(wPath, mode);
+}
+#else
+inline FILE*
+TS_tfopen(const char* aPath, const char* aMode)
+{
+  return fopen(aPath, aMode);
+}
+#endif
+
+/* RAII wrapper for FILE descriptors */
+struct ScopedCloseFileTraits
+{
+  typedef FILE* type;
+  static type empty() { return nullptr; }
+  static void release(type aFile)
+  {
+    if (aFile) {
+      fclose(aFile);
+    }
+  }
+};
+typedef Scoped<ScopedCloseFileTraits> ScopedCloseFile;
+
+static void
+XPCOMGlueUnload()
+{
+  while (sTop) {
+    CloseLibHandle(sTop->libHandle);
+
+    DependentLib* temp = sTop;
+    sTop = sTop->next;
+
+    delete temp;
+  }
+}
+
+#if defined(XP_WIN)
+// like strpbrk but finds the *last* char, not the first
+static const char*
+ns_strrpbrk(const char* string, const char* strCharSet)
+{
+  const char* found = nullptr;
+  for (; *string; ++string) {
+    for (const char* search = strCharSet; *search; ++search) {
+      if (*search == *string) {
+        found = string;
+        // Since we're looking for the last char, we save "found"
+        // until we're at the end of the string.
+      }
+    }
+  }
+
+  return found;
+}
+#endif
+
+static GetFrozenFunctionsFunc
+XPCOMGlueLoad(const char* aXPCOMFile)
+{
+  char xpcomDir[MAXPATHLEN];
+#ifdef XP_WIN
+  const char* lastSlash = ns_strrpbrk(aXPCOMFile, "/\\");
+#elif XP_MACOSX
+  // On OSX, the dependentlibs.list file lives under Contents/Resources.
+  // However, the actual libraries listed in dependentlibs.list live under
+  // Contents/MacOS. We want to read the list from Contents/Resources, then
+  // load the libraries from Contents/MacOS.
+  const char *tempSlash = strrchr(aXPCOMFile, '/');
+  size_t tempLen = size_t(tempSlash - aXPCOMFile);
+  if (tempLen > MAXPATHLEN) {
+    return nullptr;
+  }
+  char tempBuffer[MAXPATHLEN];
+  memcpy(tempBuffer, aXPCOMFile, tempLen);
+  tempBuffer[tempLen] = '\0';
+  const char *slash = strrchr(tempBuffer, '/');
+  tempLen = size_t(slash - tempBuffer);
+  const char *lastSlash = aXPCOMFile + tempLen;
+#else
+  const char* lastSlash = strrchr(aXPCOMFile, '/');
+#endif
+  char* cursor;
+  if (lastSlash) {
+    size_t len = size_t(lastSlash - aXPCOMFile);
+
+    if (len > MAXPATHLEN - sizeof(XPCOM_FILE_PATH_SEPARATOR
+#ifdef XP_MACOSX
+                                  "Resources"
+                                  XPCOM_FILE_PATH_SEPARATOR
+#endif
+                                  XPCOM_DEPENDENT_LIBS_LIST)) {
+      return nullptr;
+    }
+    memcpy(xpcomDir, aXPCOMFile, len);
+    strcpy(xpcomDir + len, XPCOM_FILE_PATH_SEPARATOR
+#ifdef XP_MACOSX
+                           "Resources"
+                           XPCOM_FILE_PATH_SEPARATOR
+#endif
+                           XPCOM_DEPENDENT_LIBS_LIST);
+    cursor = xpcomDir + len + 1;
+  } else {
+    strcpy(xpcomDir, XPCOM_DEPENDENT_LIBS_LIST);
+    cursor = xpcomDir;
+  }
+
+  if (getenv("MOZ_RUN_GTEST")) {
+    strcat(xpcomDir, ".gtest");
+  }
+
+  ScopedCloseFile flist;
+  flist = TS_tfopen(xpcomDir, READ_TEXTMODE);
+  if (!flist) {
+    return nullptr;
+  }
+
+#ifdef XP_MACOSX
+  tempLen = size_t(cursor - xpcomDir);
+  if (tempLen > MAXPATHLEN - sizeof("MacOS" XPCOM_FILE_PATH_SEPARATOR) - 1) {
+    return nullptr;
+  }
+  strcpy(cursor, "MacOS" XPCOM_FILE_PATH_SEPARATOR);
+  cursor += strlen(cursor);
+#endif
+  *cursor = '\0';
+
+  char buffer[MAXPATHLEN];
+
+  while (fgets(buffer, sizeof(buffer), flist)) {
+    int l = strlen(buffer);
+
+    // ignore empty lines and comments
+    if (l == 0 || *buffer == '#') {
+      continue;
+    }
+
+    // cut the trailing newline, if present
+    if (buffer[l - 1] == '\n') {
+      buffer[l - 1] = '\0';
+    }
+
+    if (l + size_t(cursor - xpcomDir) > MAXPATHLEN) {
+      return nullptr;
+    }
+
+    strcpy(cursor, buffer);
+    if (!ReadDependentCB(xpcomDir, do_preload)) {
+      XPCOMGlueUnload();
+      return nullptr;
+    }
+  }
+
+  GetFrozenFunctionsFunc sym =
+    (GetFrozenFunctionsFunc)GetSymbol(sTop->libHandle,
+                                      "NS_GetFrozenFunctions");
+
+  if (!sym) { // No symbol found.
+    XPCOMGlueUnload();
+    return nullptr;
+  }
+
+  return sym;
+}
+
+nsresult
+XPCOMGlueLoadXULFunctions(const nsDynamicFunctionLoad* aSymbols)
+{
+  // We don't null-check sXULLibHandle because this might work even
+  // if it is null (same as RTLD_DEFAULT)
+
+  nsresult rv = NS_OK;
+  while (aSymbols->functionName) {
+    char buffer[512];
+    SprintfLiteral(buffer, "%s", aSymbols->functionName);
+
+    *aSymbols->function = (NSFuncPtr)GetSymbol(sTop->libHandle, buffer);
+    if (!*aSymbols->function) {
+      rv = NS_ERROR_LOSS_OF_SIGNIFICANT_DATA;
+    }
+
+    ++aSymbols;
+  }
+  return rv;
+}
+
+void
+XPCOMGlueEnablePreload()
+{
+  do_preload = true;
+}
+
+#if defined(MOZ_WIDGET_GTK) && (defined(MOZ_MEMORY) || defined(__FreeBSD__) || defined(__NetBSD__))
+#define MOZ_GSLICE_INIT
+#endif
+
+#ifdef MOZ_GSLICE_INIT
+#include <glib.h>
+
+class GSliceInit {
+public:
+  GSliceInit() {
+    mHadGSlice = bool(getenv("G_SLICE"));
+    if (!mHadGSlice) {
+      // Disable the slice allocator, since jemalloc already uses similar layout
+      // algorithms, and using a sub-allocator tends to increase fragmentation.
+      // This must be done before g_thread_init() is called.
+      // glib >= 2.36 initializes g_slice as a side effect of its various static
+      // initializers, so this needs to happen before glib is loaded, which is
+      // this is hooked in XPCOMGlueStartup before libxul is loaded. This
+      // relies on the main executable not depending on glib.
+      setenv("G_SLICE", "always-malloc", 1);
+    }
+  }
+
+  ~GSliceInit() {
+#if MOZ_WIDGET_GTK == 2
+    if (sTop) {
+      auto XRE_GlibInit = (void (*)(void)) GetSymbol(sTop->libHandle,
+        "XRE_GlibInit");
+      // Initialize glib enough for G_SLICE to have an effect before it is unset.
+      // unset.
+      XRE_GlibInit();
+    }
+#endif
+    if (!mHadGSlice) {
+      unsetenv("G_SLICE");
+    }
+  }
+
+private:
+  bool mHadGSlice;
+};
+#endif
+
+nsresult
+XPCOMGlueStartup(const char* aXPCOMFile)
+{
+#ifdef MOZ_GSLICE_INIT
+  GSliceInit gSliceInit;
+#endif
+  xpcomFunctions.version = XPCOM_GLUE_VERSION;
+  xpcomFunctions.size    = sizeof(XPCOMFunctions);
+
+  if (!aXPCOMFile) {
+    aXPCOMFile = XPCOM_DLL;
+  }
+
+  GetFrozenFunctionsFunc func = XPCOMGlueLoad(aXPCOMFile);
+  if (!func) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsresult rv = (*func)(&xpcomFunctions, nullptr);
+  if (NS_FAILED(rv)) {
+    XPCOMGlueUnload();
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+XPCOM_API(nsresult)
+NS_InitXPCOM2(nsIServiceManager** aResult,
+              nsIFile* aBinDirectory,
+              nsIDirectoryServiceProvider* aAppFileLocationProvider)
+{
+  if (!xpcomFunctions.init) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.init(aResult, aBinDirectory, aAppFileLocationProvider);
+}
+
+XPCOM_API(nsresult)
+NS_ShutdownXPCOM(nsIServiceManager* aServMgr)
+{
+  if (!xpcomFunctions.shutdown) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.shutdown(aServMgr);
+}
+
+XPCOM_API(nsresult)
+NS_GetServiceManager(nsIServiceManager** aResult)
+{
+  if (!xpcomFunctions.getServiceManager) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.getServiceManager(aResult);
+}
+
+XPCOM_API(nsresult)
+NS_GetComponentManager(nsIComponentManager** aResult)
+{
+  if (!xpcomFunctions.getComponentManager) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.getComponentManager(aResult);
+}
+
+XPCOM_API(nsresult)
+NS_GetComponentRegistrar(nsIComponentRegistrar** aResult)
+{
+  if (!xpcomFunctions.getComponentRegistrar) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.getComponentRegistrar(aResult);
+}
+
+XPCOM_API(nsresult)
+NS_GetMemoryManager(nsIMemory** aResult)
+{
+  if (!xpcomFunctions.getMemoryManager) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.getMemoryManager(aResult);
+}
+
+XPCOM_API(nsresult)
+NS_NewLocalFile(const nsAString& aPath, bool aFollowLinks, nsIFile** aResult)
+{
+  if (!xpcomFunctions.newLocalFile) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.newLocalFile(aPath, aFollowLinks, aResult);
+}
+
+XPCOM_API(nsresult)
+NS_NewNativeLocalFile(const nsACString& aPath, bool aFollowLinks,
+                      nsIFile** aResult)
+{
+  if (!xpcomFunctions.newNativeLocalFile) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.newNativeLocalFile(aPath, aFollowLinks, aResult);
+}
+
+XPCOM_API(nsresult)
+NS_GetDebug(nsIDebug2** aResult)
+{
+  if (!xpcomFunctions.getDebug) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.getDebug(aResult);
+}
+
+
+XPCOM_API(nsresult)
+NS_StringContainerInit(nsStringContainer& aStr)
+{
+  if (!xpcomFunctions.stringContainerInit) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.stringContainerInit(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_StringContainerInit2(nsStringContainer& aStr, const char16_t* aData,
+                        uint32_t aDataLength, uint32_t aFlags)
+{
+  if (!xpcomFunctions.stringContainerInit2) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.stringContainerInit2(aStr, aData, aDataLength, aFlags);
+}
+
+XPCOM_API(void)
+NS_StringContainerFinish(nsStringContainer& aStr)
+{
+  if (xpcomFunctions.stringContainerFinish) {
+    xpcomFunctions.stringContainerFinish(aStr);
+  }
+}
+
+XPCOM_API(uint32_t)
+NS_StringGetData(const nsAString& aStr, const char16_t** aBuf, bool* aTerm)
+{
+  if (!xpcomFunctions.stringGetData) {
+    *aBuf = nullptr;
+    return 0;
+  }
+  return xpcomFunctions.stringGetData(aStr, aBuf, aTerm);
+}
+
+XPCOM_API(uint32_t)
+NS_StringGetMutableData(nsAString& aStr, uint32_t aLen, char16_t** aBuf)
+{
+  if (!xpcomFunctions.stringGetMutableData) {
+    *aBuf = nullptr;
+    return 0;
+  }
+  return xpcomFunctions.stringGetMutableData(aStr, aLen, aBuf);
+}
+
+XPCOM_API(char16_t*)
+NS_StringCloneData(const nsAString& aStr)
+{
+  if (!xpcomFunctions.stringCloneData) {
+    return nullptr;
+  }
+  return xpcomFunctions.stringCloneData(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_StringSetData(nsAString& aStr, const char16_t* aBuf, uint32_t aCount)
+{
+  if (!xpcomFunctions.stringSetData) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return xpcomFunctions.stringSetData(aStr, aBuf, aCount);
+}
+
+XPCOM_API(nsresult)
+NS_StringSetDataRange(nsAString& aStr, uint32_t aCutStart, uint32_t aCutLength,
+                      const char16_t* aBuf, uint32_t aCount)
+{
+  if (!xpcomFunctions.stringSetDataRange) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.stringSetDataRange(aStr, aCutStart, aCutLength, aBuf,
+                                           aCount);
+}
+
+XPCOM_API(nsresult)
+NS_StringCopy(nsAString& aDest, const nsAString& aSrc)
+{
+  if (!xpcomFunctions.stringCopy) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.stringCopy(aDest, aSrc);
+}
+
+XPCOM_API(void)
+NS_StringSetIsVoid(nsAString& aStr, const bool aIsVoid)
+{
+  if (xpcomFunctions.stringSetIsVoid) {
+    xpcomFunctions.stringSetIsVoid(aStr, aIsVoid);
+  }
+}
+
+XPCOM_API(bool)
+NS_StringGetIsVoid(const nsAString& aStr)
+{
+  if (!xpcomFunctions.stringGetIsVoid) {
+    return false;
+  }
+  return xpcomFunctions.stringGetIsVoid(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_CStringContainerInit(nsCStringContainer& aStr)
+{
+  if (!xpcomFunctions.cstringContainerInit) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringContainerInit(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_CStringContainerInit2(nsCStringContainer& aStr, const char* aData,
+                         uint32_t aDataLength, uint32_t aFlags)
+{
+  if (!xpcomFunctions.cstringContainerInit2) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringContainerInit2(aStr, aData, aDataLength, aFlags);
+}
+
+XPCOM_API(void)
+NS_CStringContainerFinish(nsCStringContainer& aStr)
+{
+  if (xpcomFunctions.cstringContainerFinish) {
+    xpcomFunctions.cstringContainerFinish(aStr);
+  }
+}
+
+XPCOM_API(uint32_t)
+NS_CStringGetData(const nsACString& aStr, const char** aBuf, bool* aTerm)
+{
+  if (!xpcomFunctions.cstringGetData) {
+    *aBuf = nullptr;
+    return 0;
+  }
+  return xpcomFunctions.cstringGetData(aStr, aBuf, aTerm);
+}
+
+XPCOM_API(uint32_t)
+NS_CStringGetMutableData(nsACString& aStr, uint32_t aLen, char** aBuf)
+{
+  if (!xpcomFunctions.cstringGetMutableData) {
+    *aBuf = nullptr;
+    return 0;
+  }
+  return xpcomFunctions.cstringGetMutableData(aStr, aLen, aBuf);
+}
+
+XPCOM_API(char*)
+NS_CStringCloneData(const nsACString& aStr)
+{
+  if (!xpcomFunctions.cstringCloneData) {
+    return nullptr;
+  }
+  return xpcomFunctions.cstringCloneData(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_CStringSetData(nsACString& aStr, const char* aBuf, uint32_t aCount)
+{
+  if (!xpcomFunctions.cstringSetData) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringSetData(aStr, aBuf, aCount);
+}
+
+XPCOM_API(nsresult)
+NS_CStringSetDataRange(nsACString& aStr, uint32_t aCutStart,
+                       uint32_t aCutLength, const char* aBuf, uint32_t aCount)
+{
+  if (!xpcomFunctions.cstringSetDataRange) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringSetDataRange(aStr, aCutStart, aCutLength, aBuf,
+                                            aCount);
+}
+
+XPCOM_API(nsresult)
+NS_CStringCopy(nsACString& aDest, const nsACString& aSrc)
+{
+  if (!xpcomFunctions.cstringCopy) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringCopy(aDest, aSrc);
+}
+
+XPCOM_API(void)
+NS_CStringSetIsVoid(nsACString& aStr, const bool aIsVoid)
+{
+  if (xpcomFunctions.cstringSetIsVoid) {
+    xpcomFunctions.cstringSetIsVoid(aStr, aIsVoid);
+  }
+}
+
+XPCOM_API(bool)
+NS_CStringGetIsVoid(const nsACString& aStr)
+{
+  if (!xpcomFunctions.cstringGetIsVoid) {
+    return false;
+  }
+  return xpcomFunctions.cstringGetIsVoid(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_CStringToUTF16(const nsACString& aSrc, nsCStringEncoding aSrcEncoding,
+                  nsAString& aDest)
+{
+  if (!xpcomFunctions.cstringToUTF16) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringToUTF16(aSrc, aSrcEncoding, aDest);
+}
+
+XPCOM_API(nsresult)
+NS_UTF16ToCString(const nsAString& aSrc, nsCStringEncoding aDestEncoding,
+                  nsACString& aDest)
+{
+  if (!xpcomFunctions.utf16ToCString) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.utf16ToCString(aSrc, aDestEncoding, aDest);
+}
+
+XPCOM_API(void*)
+NS_Alloc(size_t aSize)
+{
+  if (!xpcomFunctions.allocFunc) {
+    return nullptr;
+  }
+  return xpcomFunctions.allocFunc(aSize);
+}
+
+XPCOM_API(void*)
+NS_Realloc(void* aPtr, size_t aSize)
+{
+  if (!xpcomFunctions.reallocFunc) {
+    return nullptr;
+  }
+  return xpcomFunctions.reallocFunc(aPtr, aSize);
+}
+
+XPCOM_API(void)
+NS_Free(void* aPtr)
+{
+  if (xpcomFunctions.freeFunc) {
+    xpcomFunctions.freeFunc(aPtr);
+  }
+}
+
+XPCOM_API(void)
+NS_DebugBreak(uint32_t aSeverity, const char* aStr, const char* aExpr,
+              const char* aFile, int32_t aLine)
+{
+  if (xpcomFunctions.debugBreakFunc) {
+    xpcomFunctions.debugBreakFunc(aSeverity, aStr, aExpr, aFile, aLine);
+  }
+}
+
+XPCOM_API(void)
+NS_LogInit()
+{
+  if (xpcomFunctions.logInitFunc) {
+    xpcomFunctions.logInitFunc();
+  }
+}
+
+XPCOM_API(void)
+NS_LogTerm()
+{
+  if (xpcomFunctions.logTermFunc) {
+    xpcomFunctions.logTermFunc();
+  }
+}
+
+XPCOM_API(void)
+NS_LogAddRef(void* aPtr, nsrefcnt aNewRefCnt,
+             const char* aTypeName, uint32_t aInstanceSize)
+{
+  if (xpcomFunctions.logAddRefFunc)
+    xpcomFunctions.logAddRefFunc(aPtr, aNewRefCnt,
+                                 aTypeName, aInstanceSize);
+}
+
+XPCOM_API(void)
+NS_LogRelease(void* aPtr, nsrefcnt aNewRefCnt, const char* aTypeName)
+{
+  if (xpcomFunctions.logReleaseFunc) {
+    xpcomFunctions.logReleaseFunc(aPtr, aNewRefCnt, aTypeName);
+  }
+}
+
+XPCOM_API(void)
+NS_LogCtor(void* aPtr, const char* aTypeName, uint32_t aInstanceSize)
+{
+  if (xpcomFunctions.logCtorFunc) {
+    xpcomFunctions.logCtorFunc(aPtr, aTypeName, aInstanceSize);
+  }
+}
+
+XPCOM_API(void)
+NS_LogDtor(void* aPtr, const char* aTypeName, uint32_t aInstanceSize)
+{
+  if (xpcomFunctions.logDtorFunc) {
+    xpcomFunctions.logDtorFunc(aPtr, aTypeName, aInstanceSize);
+  }
+}
+
+XPCOM_API(void)
+NS_LogCOMPtrAddRef(void* aCOMPtr, nsISupports* aObject)
+{
+  if (xpcomFunctions.logCOMPtrAddRefFunc) {
+    xpcomFunctions.logCOMPtrAddRefFunc(aCOMPtr, aObject);
+  }
+}
+
+XPCOM_API(void)
+NS_LogCOMPtrRelease(void* aCOMPtr, nsISupports* aObject)
+{
+  if (xpcomFunctions.logCOMPtrReleaseFunc) {
+    xpcomFunctions.logCOMPtrReleaseFunc(aCOMPtr, aObject);
+  }
+}
+
+XPCOM_API(nsresult)
+NS_GetXPTCallStub(REFNSIID aIID, nsIXPTCProxy* aOuter,
+                  nsISomeInterface** aStub)
+{
+  if (!xpcomFunctions.getXPTCallStubFunc) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return xpcomFunctions.getXPTCallStubFunc(aIID, aOuter, aStub);
+}
+
+XPCOM_API(void)
+NS_DestroyXPTCallStub(nsISomeInterface* aStub)
+{
+  if (xpcomFunctions.destroyXPTCallStubFunc) {
+    xpcomFunctions.destroyXPTCallStubFunc(aStub);
+  }
+}
+
+XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* aThat, uint32_t aMethodIndex,
+                 uint32_t aParamCount, nsXPTCVariant* aParams)
+{
+  if (!xpcomFunctions.invokeByIndexFunc) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return xpcomFunctions.invokeByIndexFunc(aThat, aMethodIndex,
+                                          aParamCount, aParams);
+}
+
+XPCOM_API(bool)
+NS_CycleCollectorSuspect(nsISupports* aObj)
+{
+  if (!xpcomFunctions.cycleSuspectFunc) {
+    return false;
+  }
+
+  return xpcomFunctions.cycleSuspectFunc(aObj);
+}
+
+XPCOM_API(bool)
+NS_CycleCollectorForget(nsISupports* aObj)
+{
+  if (!xpcomFunctions.cycleForgetFunc) {
+    return false;
+  }
+
+  return xpcomFunctions.cycleForgetFunc(aObj);
+}
+
+XPCOM_API(nsPurpleBufferEntry*)
+NS_CycleCollectorSuspect2(void* aObj, nsCycleCollectionParticipant* aCp)
+{
+  if (!xpcomFunctions.cycleSuspect2Func) {
+    return nullptr;
+  }
+
+  return xpcomFunctions.cycleSuspect2Func(aObj, aCp);
+}
+
+XPCOM_API(void)
+NS_CycleCollectorSuspect3(void* aObj, nsCycleCollectionParticipant* aCp,
+                          nsCycleCollectingAutoRefCnt* aRefCnt,
+                          bool* aShouldDelete)
+{
+  if (xpcomFunctions.cycleSuspect3Func) {
+    xpcomFunctions.cycleSuspect3Func(aObj, aCp, aRefCnt, aShouldDelete);
+  }
+}
+
+XPCOM_API(bool)
+NS_CycleCollectorForget2(nsPurpleBufferEntry* aEntry)
+{
+  if (!xpcomFunctions.cycleForget2Func) {
+    return false;
+  }
+
+  return xpcomFunctions.cycleForget2Func(aEntry);
+}
diff --git a/xpcom/glue/standalone/nsXPCOMGlue.h b/xpcom/glue/standalone/nsXPCOMGlue.h
new file mode 100644
index 0000000000..e23bfa4981
--- /dev/null
+++ b/xpcom/glue/standalone/nsXPCOMGlue.h
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPCOMGlue_h__
+#define nsXPCOMGlue_h__
+
+#include "nscore.h"
+
+#ifdef XPCOM_GLUE
+
+/**
+ * The following functions are only available in the standalone glue.
+ */
+
+/**
+ * Enabled preloading of dynamically loaded libraries
+ */
+extern "C" NS_HIDDEN_(void) XPCOMGlueEnablePreload();
+
+/**
+ * Initialize the XPCOM glue by dynamically linking against the XPCOM
+ * shared library indicated by xpcomFile.
+ */
+extern "C" NS_HIDDEN_(nsresult) XPCOMGlueStartup(const char* aXPCOMFile);
+
+typedef void (*NSFuncPtr)();
+
+struct nsDynamicFunctionLoad
+{
+  const char* functionName;
+  NSFuncPtr* function;
+};
+
+/**
+ * Dynamically load functions from libxul.
+ *
+ * @throws NS_ERROR_NOT_INITIALIZED if XPCOMGlueStartup() was not called or
+ *         if the libxul DLL was not found.
+ * @throws NS_ERROR_LOSS_OF_SIGNIFICANT_DATA if only some of the required
+ *         functions were found.
+ */
+extern "C" NS_HIDDEN_(nsresult)
+XPCOMGlueLoadXULFunctions(const nsDynamicFunctionLoad* aSymbols);
+
+#endif // XPCOM_GLUE
+#endif // nsXPCOMGlue_h__
diff --git a/xpcom/glue/standalone/staticruntime/moz.build b/xpcom/glue/standalone/staticruntime/moz.build
new file mode 100644
index 0000000000..735086ab0b
--- /dev/null
+++ b/xpcom/glue/standalone/staticruntime/moz.build
@@ -0,0 +1,50 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../../objs.mozbuild')
+
+SOURCES += xpcom_glue_src_cppsrcs
+
+SOURCES += [
+    '../../nsStringAPI.cpp',
+    '../nsXPCOMGlue.cpp',
+]
+
+Library('xpcomglue_staticruntime')
+
+SDK_LIBRARY = True
+
+# create a static lib
+FORCE_STATIC_LIB = True
+
+if CONFIG['_MSC_VER']:
+    DEFINES['_USE_ANSI_CPP'] = True
+    # Don't include directives about which CRT to use
+    CFLAGS += ['-Zl']
+    CXXFLAGS += ['-Zl']
+
+DEFINES['XPCOM_GLUE'] = True
+
+LOCAL_INCLUDES += [
+    '../../../build',
+    '../../../threads',
+]
+
+# Statically link to the CRT on Windows
+USE_STATIC_LIBS = True
+
+# Don't use STL wrappers here (i.e. wrapped <new>); they require mozalloc
+DISABLE_STL_WRAPPING = True
+
+# Include fallible for third party code using the xpcom glue
+USE_LIBS += [
+    'fallible',
+]
+
+# Force to build a static library only
+NO_EXPAND_LIBS = True
+
+DIST_INSTALL = True
diff --git a/xpcom/glue/staticruntime/moz.build b/xpcom/glue/staticruntime/moz.build
new file mode 100644
index 0000000000..384bc6878f
--- /dev/null
+++ b/xpcom/glue/staticruntime/moz.build
@@ -0,0 +1,48 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../objs.mozbuild')
+
+UNIFIED_SOURCES += xpcom_gluens_src_cppsrcs
+UNIFIED_SOURCES += xpcom_glue_src_cppsrcs
+
+UNIFIED_SOURCES += [
+    '../GenericModule.cpp',
+    '../nsStringAPI.cpp',
+]
+
+Library('xpcomglue_staticruntime_s')
+
+SDK_LIBRARY = True
+
+FORCE_STATIC_LIB = True
+
+if CONFIG['_MSC_VER']:
+    DEFINES['_USE_ANSI_CPP'] = True
+    # Don't include directives about which CRT to use
+    CFLAGS += ['-Zl']
+    CXXFLAGS += ['-Zl']
+
+LOCAL_INCLUDES += [
+    '../../build',
+    '../../threads',
+]
+
+# Statically link to the CRT on Windows
+USE_STATIC_LIBS = True
+
+# Don't use STL wrappers here (i.e. wrapped <new>); they require mozalloc
+DISABLE_STL_WRAPPING = True
+
+# Include fallible for third party code using the xpcom glue
+USE_LIBS += [
+    'fallible',
+]
+
+# Force to build a static library only
+NO_EXPAND_LIBS = True
+
+DIST_INSTALL = True
diff --git a/xpcom/glue/tests/gtest/TestArray.cpp b/xpcom/glue/tests/gtest/TestArray.cpp
new file mode 100644
index 0000000000..72d28b4dff
--- /dev/null
+++ b/xpcom/glue/tests/gtest/TestArray.cpp
@@ -0,0 +1,169 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "gtest/gtest.h"
+
+// Disable deprecation warnings generated by nsISupportsArray and associated
+// classes.
+#if defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#elif defined(_MSC_VER)
+#pragma warning (push)
+#pragma warning (disable : 4996)
+#endif
+
+#include "nsISupportsArray.h"
+
+// {9e70a320-be02-11d1-8031-006008159b5a}
+#define NS_IFOO_IID \
+  {0x9e70a320, 0xbe02, 0x11d1,    \
+    {0x80, 0x31, 0x00, 0x60, 0x08, 0x15, 0x9b, 0x5a}}
+
+namespace TestArray {
+
+class IFoo : public nsISupports {
+public:
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IFOO_IID)
+
+  NS_IMETHOD_(nsrefcnt) RefCnt() = 0;
+  NS_IMETHOD_(int32_t) ID() = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(IFoo, NS_IFOO_IID)
+
+class Foo final : public IFoo {
+public:
+
+  explicit Foo(int32_t aID);
+
+  // nsISupports implementation
+  NS_DECL_ISUPPORTS
+
+  // IFoo implementation
+  NS_IMETHOD_(nsrefcnt) RefCnt() override { return mRefCnt; }
+  NS_IMETHOD_(int32_t) ID() override { return mID; }
+
+  static int32_t gCount;
+
+  int32_t mID;
+
+private:
+  ~Foo();
+};
+
+int32_t Foo::gCount;
+
+Foo::Foo(int32_t aID)
+{
+  mID = aID;
+  ++gCount;
+}
+
+Foo::~Foo()
+{
+  --gCount;
+}
+
+NS_IMPL_ISUPPORTS(Foo, IFoo)
+
+void CheckArray(nsISupportsArray* aArray, int32_t aExpectedCount, int32_t aElementIDs[], int32_t aExpectedTotal)
+{
+  uint32_t cnt = 0;
+#ifdef DEBUG
+  nsresult rv =
+#endif
+    aArray->Count(&cnt);
+  NS_ASSERTION(NS_SUCCEEDED(rv), "Count failed");
+  int32_t count = cnt;
+  int32_t index;
+
+  EXPECT_EQ(Foo::gCount, aExpectedTotal);
+  EXPECT_EQ(count, aExpectedCount);
+
+  for (index = 0; (index < count) && (index < aExpectedCount); index++) {
+    nsCOMPtr<IFoo> foo = do_QueryElementAt(aArray, index);
+    EXPECT_EQ(foo->ID(), aElementIDs[index]);
+  }
+}
+
+void FillArray(nsISupportsArray* aArray, int32_t aCount)
+{
+  int32_t index;
+  for (index = 0; index < aCount; index++) {
+    nsCOMPtr<IFoo> foo = new Foo(index);
+    aArray->AppendElement(foo);
+  }
+}
+
+} // namespace TestArray
+
+using namespace TestArray;
+
+TEST(Array, main)
+{
+  nsISupportsArray* array;
+  nsresult  rv;
+
+  if (NS_OK == (rv = NS_NewISupportsArray(&array))) {
+    FillArray(array, 10);
+    int32_t   fillResult[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+    CheckArray(array, 10, fillResult, 10);
+
+    // test insert
+    nsCOMPtr<IFoo> foo = do_QueryElementAt(array, 3);
+    array->InsertElementAt(foo, 5);
+    int32_t   insertResult[11] = {0, 1, 2, 3, 4, 3, 5, 6, 7, 8, 9};
+    CheckArray(array, 11, insertResult, 10);
+    array->InsertElementAt(foo, 0);
+    int32_t   insertResult2[12] = {3, 0, 1, 2, 3, 4, 3, 5, 6, 7, 8, 9};
+    CheckArray(array, 12, insertResult2, 10);
+    array->AppendElement(foo);
+    int32_t   appendResult[13] = {3, 0, 1, 2, 3, 4, 3, 5, 6, 7, 8, 9, 3};
+    CheckArray(array, 13, appendResult, 10);
+
+
+    // test IndexOf
+    int32_t expectedIndex = 0;
+    int32_t index = array->IndexOf(foo);
+    EXPECT_EQ(index, expectedIndex);
+
+    // test ReplaceElementAt
+    array->ReplaceElementAt(foo, 8);
+    int32_t   replaceResult[13] = {3, 0, 1, 2, 3, 4, 3, 5, 3, 7, 8, 9, 3};
+    CheckArray(array, 13, replaceResult, 9);
+
+    // test RemoveElementAt, RemoveElement
+    array->RemoveElementAt(0);
+    int32_t   removeResult[12] = {0, 1, 2, 3, 4, 3, 5, 3, 7, 8, 9, 3};
+    CheckArray(array, 12, removeResult, 9);
+    array->RemoveElementAt(7);
+    int32_t   removeResult2[11] = {0, 1, 2, 3, 4, 3, 5, 7, 8, 9, 3};
+    CheckArray(array, 11, removeResult2, 9);
+    array->RemoveElement(foo);
+    int32_t   removeResult3[10] = {0, 1, 2, 4, 3, 5, 7, 8, 9, 3};
+    CheckArray(array, 10, removeResult3, 9);
+
+    foo = nullptr;
+
+    // test clear
+    array->Clear();
+    FillArray(array, 4);
+    CheckArray(array, 4, fillResult, 4);
+
+    // test delete
+    NS_RELEASE(array);
+  }
+}
+
+#if defined(__GNUC__)
+#pragma GCC diagnostic pop
+#elif defined(_MSC_VER)
+#pragma warning (pop)
+#endif
diff --git a/xpcom/glue/tests/gtest/TestFileUtils.cpp b/xpcom/glue/tests/gtest/TestFileUtils.cpp
new file mode 100644
index 0000000000..55106c6c5f
--- /dev/null
+++ b/xpcom/glue/tests/gtest/TestFileUtils.cpp
@@ -0,0 +1,283 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+/* Test ReadSysFile() */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "FileUtils.h"
+
+#include "gtest/gtest.h"
+
+namespace mozilla {
+
+#ifdef ReadSysFile_PRESENT
+
+/**
+ * Create a file with the specified contents.
+ */
+static bool
+WriteFile(
+  const char* aFilename,
+  const void* aContents,
+  size_t aContentsLen)
+{
+  int fd;
+  ssize_t ret;
+  size_t offt;
+
+  fd = MOZ_TEMP_FAILURE_RETRY(
+    open(aFilename, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR));
+  if (fd == -1) {
+    fprintf(stderr, "open(): %s: %s\n", aFilename, strerror(errno));
+    return false;
+  }
+
+  offt = 0;
+  do {
+    ret = MOZ_TEMP_FAILURE_RETRY(
+      write(fd, (char*)aContents + offt, aContentsLen - offt));
+    if (ret == -1) {
+      fprintf(stderr, "write(): %s: %s\n", aFilename, strerror(errno));
+      close(fd);
+      return false;
+    }
+    offt += ret;
+  } while (offt < aContentsLen);
+
+  ret = MOZ_TEMP_FAILURE_RETRY(close(fd));
+  if (ret == -1) {
+    fprintf(stderr, "close(): %s: %s\n", aFilename, strerror(errno));
+    return false;
+  }
+  return true;
+}
+
+TEST(ReadSysFile, Nonexistent) {
+  bool ret;
+  int errno_saved;
+
+  ret = ReadSysFile("/nonexistent", nullptr, 0);
+  errno_saved = errno;
+
+  ASSERT_FALSE(ret);
+  ASSERT_EQ(errno_saved, ENOENT);
+}
+
+TEST(ReadSysFile, Main) {
+  /* Use a different file name for each test since different tests could be
+  executed concurrently. */
+  static const char* fn = "TestReadSysFileMain";
+  /* If we have a file which contains "abcd" and we read it with ReadSysFile(),
+  providing a buffer of size 10 bytes, we would expect 5 bytes to be written
+  to that buffer: "abcd\0". */
+  struct
+  {
+    /* input (file contents), e.g. "abcd" */
+    const char* input;
+    /* pretended output buffer size, e.g. 10; the actual buffer is larger
+    and we check if anything was written past the end of the allowed length */
+    size_t output_size;
+    /* expected number of bytes written to the output buffer, including the
+    terminating '\0', e.g. 5 */
+    size_t output_len;
+    /* expected output buffer contents, e.g. "abcd\0", the first output_len
+    bytes of the output buffer should match the first 'output_len' bytes from
+    'output', the rest of the output buffer should be untouched. */
+    const char* output;
+  } tests[] = {
+    /* No new lines */
+    {"", 0, 0, ""},
+    {"", 1, 1, "\0"}, /* \0 is redundant, but we write it for clarity */
+    {"", 9, 1, "\0"},
+
+    {"a", 0, 0, ""},
+    {"a", 1, 1, "\0"},
+    {"a", 2, 2, "a\0"},
+    {"a", 9, 2, "a\0"},
+
+    {"abcd", 0, 0, ""},
+    {"abcd", 1, 1, "\0"},
+    {"abcd", 2, 2, "a\0"},
+    {"abcd", 3, 3, "ab\0"},
+    {"abcd", 4, 4, "abc\0"},
+    {"abcd", 5, 5, "abcd\0"},
+    {"abcd", 9, 5, "abcd\0"},
+
+    /* A single trailing new line */
+    {"\n", 0, 0, ""},
+    {"\n", 1, 1, "\0"},
+    {"\n", 2, 1, "\0"},
+    {"\n", 9, 1, "\0"},
+
+    {"a\n", 0, 0, ""},
+    {"a\n", 1, 1, "\0"},
+    {"a\n", 2, 2, "a\0"},
+    {"a\n", 3, 2, "a\0"},
+    {"a\n", 9, 2, "a\0"},
+
+    {"abcd\n", 0, 0, ""},
+    {"abcd\n", 1, 1, "\0"},
+    {"abcd\n", 2, 2, "a\0"},
+    {"abcd\n", 3, 3, "ab\0"},
+    {"abcd\n", 4, 4, "abc\0"},
+    {"abcd\n", 5, 5, "abcd\0"},
+    {"abcd\n", 6, 5, "abcd\0"},
+    {"abcd\n", 9, 5, "abcd\0"},
+
+    /* Multiple trailing new lines */
+    {"\n\n", 0, 0, ""},
+    {"\n\n", 1, 1, "\0"},
+    {"\n\n", 2, 2, "\n\0"},
+    {"\n\n", 3, 2, "\n\0"},
+    {"\n\n", 9, 2, "\n\0"},
+
+    {"a\n\n", 0, 0, ""},
+    {"a\n\n", 1, 1, "\0"},
+    {"a\n\n", 2, 2, "a\0"},
+    {"a\n\n", 3, 3, "a\n\0"},
+    {"a\n\n", 4, 3, "a\n\0"},
+    {"a\n\n", 9, 3, "a\n\0"},
+
+    {"abcd\n\n", 0, 0, ""},
+    {"abcd\n\n", 1, 1, "\0"},
+    {"abcd\n\n", 2, 2, "a\0"},
+    {"abcd\n\n", 3, 3, "ab\0"},
+    {"abcd\n\n", 4, 4, "abc\0"},
+    {"abcd\n\n", 5, 5, "abcd\0"},
+    {"abcd\n\n", 6, 6, "abcd\n\0"},
+    {"abcd\n\n", 7, 6, "abcd\n\0"},
+    {"abcd\n\n", 9, 6, "abcd\n\0"},
+
+    /* New line in the middle */
+    {"ab\ncd", 9, 6, "ab\ncd\0"},
+  };
+
+  for (size_t i = 0; i < sizeof(tests) / sizeof(tests[0]); i++) {
+    ASSERT_TRUE(WriteFile(fn, tests[i].input, strlen(tests[i].input)));
+    /* Leave the file to exist if some of the assertions fail. */
+
+    char buf[128];
+    static const char unmodified = 'X';
+
+    memset(buf, unmodified, sizeof(buf));
+
+    ASSERT_TRUE(ReadSysFile(fn, buf, tests[i].output_size));
+
+    if (tests[i].output_size == 0) {
+      /* The buffer must be unmodified. We check only the first byte. */
+      ASSERT_EQ(unmodified, buf[0]);
+    } else {
+      ASSERT_EQ(tests[i].output_len, strlen(buf) + 1);
+      ASSERT_STREQ(tests[i].output, buf);
+      /* Check that the first byte after the trailing '\0' has not been
+      modified. */
+      ASSERT_EQ(unmodified, buf[tests[i].output_len]);
+    }
+  }
+
+  unlink(fn);
+}
+
+TEST(ReadSysFile, Int) {
+  static const char* fn = "TestReadSysFileInt";
+  struct
+  {
+    /* input (file contents), e.g. "5" */
+    const char* input;
+    /* expected return value, if false, then the output is not checked */
+    bool ret;
+    /* expected result */
+    int output;
+  } tests[] = {
+    {"0", true, 0},
+    {"00", true, 0},
+    {"1", true, 1},
+    {"5", true, 5},
+    {"55", true, 55},
+
+    {" 123", true, 123},
+    {"123 ", true, 123},
+    {" 123 ", true, 123},
+    {"123\n", true, 123},
+
+    {"", false, 0},
+    {" ", false, 0},
+    {"a", false, 0},
+
+    {"-1", true, -1},
+    {" -456 ", true, -456},
+    {" -78.9 ", true, -78},
+  };
+
+  for (size_t i = 0; i < sizeof(tests) / sizeof(tests[0]); i++) {
+    ASSERT_TRUE(WriteFile(fn, tests[i].input, strlen(tests[i].input)));
+    /* Leave the file to exist if some of the assertions fail. */
+
+    bool ret;
+    int output = 424242;
+
+    ret = ReadSysFile(fn, &output);
+
+    ASSERT_EQ(tests[i].ret, ret);
+
+    if (ret) {
+      ASSERT_EQ(tests[i].output, output);
+    }
+  }
+
+  unlink(fn);
+}
+
+TEST(ReadSysFile, Bool) {
+  static const char* fn = "TestReadSysFileBool";
+  struct
+  {
+    /* input (file contents), e.g. "1" */
+    const char* input;
+    /* expected return value */
+    bool ret;
+    /* expected result */
+    bool output;
+  } tests[] = {
+    {"0", true, false},
+    {"00", true, false},
+    {"1", true, true},
+    {"5", true, true},
+    {"23", true, true},
+    {"-1", true, true},
+
+    {"", false, true /* unused */},
+  };
+
+  for (size_t i = 0; i < sizeof(tests) / sizeof(tests[0]); i++) {
+    ASSERT_TRUE(WriteFile(fn, tests[i].input, strlen(tests[i].input)));
+    /* Leave the file to exist if some of the assertions fail. */
+
+    bool ret;
+    bool output;
+
+    ret = ReadSysFile(fn, &output);
+
+    ASSERT_EQ(tests[i].ret, ret);
+
+    if (ret) {
+      ASSERT_EQ(tests[i].output, output);
+    }
+  }
+
+  unlink(fn);
+}
+
+#endif /* ReadSysFile_PRESENT */
+
+} // namespace mozilla
diff --git a/xpcom/glue/tests/gtest/TestGCPostBarriers.cpp b/xpcom/glue/tests/gtest/TestGCPostBarriers.cpp
new file mode 100644
index 0000000000..5bf10ab059
--- /dev/null
+++ b/xpcom/glue/tests/gtest/TestGCPostBarriers.cpp
@@ -0,0 +1,140 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Tests that generational garbage collection post-barriers are correctly
+ * implemented for nsTArrays that contain JavaScript Values.
+ */
+
+#include "jsapi.h"
+#include "nsTArray.h"
+
+#include "gtest/gtest.h"
+
+#include "js/TracingAPI.h"
+#include "js/HeapAPI.h"
+
+#include "mozilla/CycleCollectedJSContext.h"
+
+using namespace JS;
+using namespace mozilla;
+
+template<class ArrayT>
+static void
+TraceArray(JSTracer* trc, void* data)
+{
+  ArrayT* array = static_cast<ArrayT *>(data);
+  for (unsigned i = 0; i < array->Length(); ++i)
+    JS::TraceEdge(trc, &array->ElementAt(i), "array-element");
+}
+
+/*
+ * Use arrays with initial size much smaller than the final number of elements
+ * to test that moving Heap<T> elements works correctly.
+ */
+const size_t ElementCount = 100;
+const size_t InitialElements = ElementCount / 10;
+
+template<class ArrayT>
+static void
+RunTest(JSContext* cx, ArrayT* array)
+{
+  JS_GC(cx);
+
+  ASSERT_TRUE(array != nullptr);
+  JS_AddExtraGCRootsTracer(cx, TraceArray<ArrayT>, array);
+
+  /*
+   * Create the array and fill it with new JS objects. With GGC these will be
+   * allocated in the nursery.
+   */
+  RootedValue value(cx);
+  const char* property = "foo";
+  for (size_t i = 0; i < ElementCount; ++i) {
+    RootedObject obj(cx, JS_NewPlainObject(cx));
+    ASSERT_FALSE(JS::ObjectIsTenured(obj));
+    value = Int32Value(i);
+    ASSERT_TRUE(JS_SetProperty(cx, obj, property, value));
+    ASSERT_TRUE(array->AppendElement(obj, fallible));
+  }
+
+  /*
+   * If postbarriers are not working, we will crash here when we try to mark
+   * objects that have been moved to the tenured heap.
+   */
+  JS_GC(cx);
+
+  /*
+   * Sanity check that our array contains what we expect.
+   */
+  for (size_t i = 0; i < ElementCount; ++i) {
+    RootedObject obj(cx, array->ElementAt(i));
+    ASSERT_TRUE(JS::ObjectIsTenured(obj));
+    ASSERT_TRUE(JS_GetProperty(cx, obj, property, &value));
+    ASSERT_TRUE(value.isInt32());
+    ASSERT_EQ(static_cast<int32_t>(i), value.toInt32());
+  }
+
+  JS_RemoveExtraGCRootsTracer(cx, TraceArray<ArrayT>, array);
+}
+
+static void
+CreateGlobalAndRunTest(JSContext* cx)
+{
+  static const JSClassOps GlobalClassOps = {
+    nullptr, nullptr, nullptr, nullptr,
+    nullptr, nullptr, nullptr, nullptr,
+    nullptr, nullptr, nullptr,
+    JS_GlobalObjectTraceHook
+  };
+
+  static const JSClass GlobalClass = {
+    "global", JSCLASS_GLOBAL_FLAGS,
+    &GlobalClassOps
+  };
+
+  JS::CompartmentOptions options;
+  options.behaviors().setVersion(JSVERSION_LATEST);
+  JS::PersistentRootedObject global(cx);
+  global = JS_NewGlobalObject(cx, &GlobalClass, nullptr, JS::FireOnNewGlobalHook, options);
+  ASSERT_TRUE(global != nullptr);
+
+  JSCompartment *oldCompartment = JS_EnterCompartment(cx, global);
+
+  typedef Heap<JSObject*> ElementT;
+
+  {
+    nsTArray<ElementT>* array = new nsTArray<ElementT>(InitialElements);
+    RunTest(cx, array);
+    delete array;
+  }
+
+  {
+    FallibleTArray<ElementT>* array = new FallibleTArray<ElementT>(InitialElements);
+    RunTest(cx, array);
+    delete array;
+  }
+
+  {
+    AutoTArray<ElementT, InitialElements> array;
+    RunTest(cx, &array);
+  }
+
+  JS_LeaveCompartment(cx, oldCompartment);
+}
+
+TEST(GCPostBarriers, nsTArray) {
+  CycleCollectedJSContext* ccjscx = CycleCollectedJSContext::Get();
+  ASSERT_TRUE(ccjscx != nullptr);
+  JSContext* cx = ccjscx->Context();
+  ASSERT_TRUE(cx != nullptr);
+
+  JS_BeginRequest(cx);
+
+  CreateGlobalAndRunTest(cx);
+
+  JS_EndRequest(cx);
+}
diff --git a/xpcom/glue/tests/gtest/TestNsDeque.cpp b/xpcom/glue/tests/gtest/TestNsDeque.cpp
new file mode 100644
index 0000000000..b84e1b781c
--- /dev/null
+++ b/xpcom/glue/tests/gtest/TestNsDeque.cpp
@@ -0,0 +1,342 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "gtest/gtest.h"
+#include "nsDeque.h"
+#include "nsCRT.h"
+#include <stdio.h>
+
+/**************************************************************
+  Now define the token deallocator class...
+ **************************************************************/
+namespace TestNsDeque {
+  
+  class _Dealloc: public nsDequeFunctor 
+  {
+    virtual void* operator()(void* aObject) {
+      return 0;
+    }
+  };
+
+  static bool VerifyContents(const nsDeque& aDeque, const int* aContents, size_t aLength) 
+  {
+    for (size_t i=0; i<aLength; ++i) {
+      if (*(int*)aDeque.ObjectAt(i) != aContents[i]) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  class Deallocator: public nsDequeFunctor
+  {
+    virtual void* operator()(void* aObject) 
+    {
+      if (aObject) 
+      {
+        // Set value to -1, to use in test function.
+        *((int*)aObject) = -1;
+      }
+
+      return nullptr;
+    }
+  };
+
+  class ForEachAdder: public nsDequeFunctor
+  {
+    virtual void* operator()(void* aObject) 
+    {
+      if (aObject) 
+      {
+        sum += *(int*)aObject;
+      }
+
+      return aObject;
+    }
+
+    private:
+     int sum = 0;
+    
+    public:
+     int GetSum() { return sum; }
+    
+  };
+}
+
+using namespace TestNsDeque;
+
+TEST(NsDeque, OriginalTest)
+{
+  const size_t size = 200;
+  int ints[size];
+  size_t i=0;
+  int temp;
+  nsDeque theDeque(new _Dealloc); //construct a simple one...
+ 
+  // ints = [0...199]
+  for (i=0;i<size;i++) { //initialize'em
+    ints[i]=static_cast<int>(i);
+  }
+  // queue = [0...69]
+  for (i=0;i<70;i++) {
+    theDeque.Push(&ints[i]);
+    temp=*(int*)theDeque.Peek();
+    EXPECT_EQ(static_cast<int>(i), temp) << "Verify end after push #1";
+    EXPECT_EQ(i + 1, theDeque.GetSize()) << "Verify size after push #1";
+  }
+
+  EXPECT_EQ(70u,theDeque.GetSize()) << "Verify overall size after pushes #1";
+
+  // queue = [0...14]
+  for (i=1;i<=55;i++) {
+    temp=*(int*)theDeque.Pop();
+    EXPECT_EQ(70-static_cast<int>(i),temp) << "Verify end after pop # 1";
+    EXPECT_EQ(70u - i,theDeque.GetSize()) << "Verify size after pop # 1";
+  }
+  EXPECT_EQ(15u,theDeque.GetSize()) << "Verify overall size after pops";
+
+  // queue = [0...14,0...54]
+  for (i=0;i<55;i++) {
+    theDeque.Push(&ints[i]);
+    temp=*(int*)theDeque.Peek();
+    EXPECT_EQ(static_cast<int>(i),temp) << "Verify end after push #2";
+    EXPECT_EQ(i + 15u + 1,theDeque.GetSize()) << "Verify size after push # 2";
+  }
+  EXPECT_EQ(70u,theDeque.GetSize()) << "Verify size after end of all pushes #2";
+
+  // queue = [0...14,0...19]
+  for (i=1;i<=35;i++) {
+    temp=*(int*)theDeque.Pop();
+    EXPECT_EQ(55-static_cast<int>(i),temp ) << "Verify end after pop # 2";
+    EXPECT_EQ(70u - i,theDeque.GetSize()) << "Verify size after pop #2";
+  }
+  EXPECT_EQ(35u,theDeque.GetSize()) << "Verify overall size after end of all pops #2";
+
+  // queue = [0...14,0...19,0...34]
+  for (i=0;i<35;i++) {
+    theDeque.Push(&ints[i]);
+    temp = *(int*)theDeque.Peek();
+    EXPECT_EQ(static_cast<int>(i),temp) << "Verify end after push # 3";
+    EXPECT_EQ(35u + 1u + i,theDeque.GetSize()) << "Verify size after push #3";
+  }
+
+  // queue = [0...14,0...19]
+  for (i=0;i<35;i++) {
+    temp=*(int*)theDeque.Pop();
+    EXPECT_EQ(34 - static_cast<int>(i), temp) << "Verify end after pop # 3";
+  }
+
+  // queue = [0...14]
+  for (i=0;i<20;i++) {
+    temp=*(int*)theDeque.Pop();
+    EXPECT_EQ(19 - static_cast<int>(i),temp) << "Verify end after pop # 4";
+  }
+
+  // queue = []
+  for (i=0;i<15;i++) {
+    temp=*(int*)theDeque.Pop();
+    EXPECT_EQ(14 - static_cast<int>(i),temp) << "Verify end after pop # 5";
+  }
+
+  EXPECT_EQ(0u,theDeque.GetSize()) << "Deque should finish empty.";
+}
+
+TEST(NsDeque, OriginalFlaw)
+{
+  int ints[200];
+  int i=0;
+  int temp;
+  nsDeque d(new _Dealloc);
+  /**
+   * Test 1. Origin near end, semi full, call Peek().
+   * you start, mCapacity is 8
+   */
+  for (i=0; i<30; i++)
+    ints[i]=i;
+
+  for (i=0; i<6; i++) {
+    d.Push(&ints[i]);
+    temp = *(int*)d.Peek();
+    EXPECT_EQ(i, temp) << "OriginalFlaw push #1";
+  }
+  EXPECT_EQ(6u, d.GetSize()) << "OriginalFlaw size check #1";
+
+  for (i=0; i<4; i++) {
+    temp=*(int*)d.PopFront();
+    EXPECT_EQ(i, temp) << "PopFront test";
+  }
+  // d = [4,5]
+  EXPECT_EQ(2u, d.GetSize()) << "OriginalFlaw size check #2";
+
+  for (i=0; i<4; i++) {
+    d.Push(&ints[6 + i]);
+  }
+
+  // d = [4...9]
+  for (i=4; i<=9; i++) {
+    temp=*(int*)d.PopFront();
+    EXPECT_EQ(i, temp) << "OriginalFlaw empty check";
+  }
+}
+
+TEST(NsDeque, TestObjectAt)
+{
+  nsDeque d;
+  const int count = 10;
+  int ints[count];
+  for (int i=0; i<count; i++) {
+    ints[i] = i;
+  }
+
+  for (int i=0; i<6; i++) {
+    d.Push(&ints[i]);
+  }
+  // d = [0...5]
+  d.PopFront();
+  d.PopFront();
+
+  // d = [2..5]
+  for (size_t i=2; i<=5; i++) {
+    int t = *(int*)d.ObjectAt(i-2);
+    EXPECT_EQ(static_cast<int>(i),t) << "Verify ObjectAt()";
+  }
+}
+
+TEST(NsDeque, TestPushFront)
+{
+  // PushFront has some interesting corner cases, primarily we're interested in whether:
+  // - wrapping around works properly
+  // - growing works properly
+
+  nsDeque d;
+
+  const int kPoolSize = 10;
+  const size_t kMaxSizeBeforeGrowth = 8;
+
+  int pool[kPoolSize];
+  for (int i = 0; i < kPoolSize; i++) {
+    pool[i] = i;
+  }
+
+  for (size_t i = 0; i < kMaxSizeBeforeGrowth; i++) {
+    d.PushFront(pool + i);
+  }
+
+  EXPECT_EQ(kMaxSizeBeforeGrowth, d.GetSize()) << "verify size";
+
+  static const int t1[] = {7,6,5,4,3,2,1,0};
+  EXPECT_TRUE(VerifyContents(d, t1, kMaxSizeBeforeGrowth)) << "verify pushfront 1";
+
+  // Now push one more so it grows
+  d.PushFront(pool + kMaxSizeBeforeGrowth);
+  EXPECT_EQ(kMaxSizeBeforeGrowth + 1, d.GetSize()) << "verify size";
+
+  static const int t2[] = {8,7,6,5,4,3,2,1,0};
+  EXPECT_TRUE(VerifyContents(d, t2, kMaxSizeBeforeGrowth + 1)) << "verify pushfront 2";
+
+  // And one more so that it wraps again
+  d.PushFront(pool + kMaxSizeBeforeGrowth + 1);
+  EXPECT_EQ(kMaxSizeBeforeGrowth + 2, d.GetSize()) << "verify size";
+
+  static const int t3[] = {9,8,7,6,5,4,3,2,1,0};
+  EXPECT_TRUE(VerifyContents(d, t3, kMaxSizeBeforeGrowth + 2)) <<"verify pushfront 3";
+}
+
+void CheckIfQueueEmpty(nsDeque& d)
+{
+  EXPECT_EQ(0u, d.GetSize())         << "Size should be 0";
+  EXPECT_EQ(nullptr, d.Pop())       <<  "Invalid operation should return nullptr";
+  EXPECT_EQ(nullptr, d.PopFront())  <<  "Invalid operation should return nullptr";
+  EXPECT_EQ(nullptr, d.Peek())      <<  "Invalid operation should return nullptr";
+  EXPECT_EQ(nullptr, d.PeekFront()) <<  "Invalid operation should return nullptr";
+  EXPECT_EQ(nullptr, d.ObjectAt(0u)) <<  "Invalid operation should return nullptr";
+}
+
+TEST(NsDeque,TestEmpty)
+{
+  // Make sure nsDeque gives sane results if it's empty.
+  nsDeque d;
+  size_t numberOfEntries = 8;
+
+  CheckIfQueueEmpty(d);
+
+  // Fill it up and drain it.
+  for (size_t i = 0; i < numberOfEntries; i++) {
+    d.Push((void*)0xAA);
+  }
+
+  EXPECT_EQ(numberOfEntries, d.GetSize());
+
+  for (size_t i = 0; i < numberOfEntries; i++) {
+    (void)d.Pop();
+  }
+
+  // Now check it again.
+  CheckIfQueueEmpty(d);
+}
+
+TEST(NsDeque,TestEraseMethod)
+{
+  nsDeque d;
+  const size_t numberOfEntries = 8;
+
+  // Fill it up before calling Erase
+  for (size_t i = 0; i < numberOfEntries; i++) {
+    d.Push((void*)0xAA);
+  }
+
+  // Call Erase
+  d.Erase();
+
+  // Now check it again.
+  CheckIfQueueEmpty(d);
+}
+
+TEST(NsDeque,TestEraseShouldCallDeallocator)
+{
+  nsDeque d(new Deallocator());
+  const size_t NumTestValues = 8;
+
+  int* testArray[NumTestValues];
+  for (size_t i=0; i < NumTestValues; i++)
+  {
+    testArray[i] = new int();
+    *(testArray[i]) = i;
+    d.Push((void*)testArray[i]);
+  }
+
+  d.Erase();
+
+  // Now check it again.
+  CheckIfQueueEmpty(d);
+  
+  for (size_t i=0; i < NumTestValues; i++)
+  {
+    EXPECT_EQ(-1, *(testArray[i])) << "Erase should call deallocator: " << *(testArray[i]);
+  }
+}
+
+TEST(NsDeque, TestForEach)
+{
+  nsDeque d(new Deallocator());
+  const size_t NumTestValues = 8;
+  int sum = 0;
+
+  int* testArray[NumTestValues];
+  for (size_t i=0; i < NumTestValues; i++)
+  {
+    testArray[i] = new int();
+    *(testArray[i]) = i;
+    sum += i;
+    d.Push((void*)testArray[i]);
+  }
+
+  ForEachAdder adder;
+  d.ForEach(adder);
+  EXPECT_EQ(sum, adder.GetSum()) << "For each should iterate over values";
+
+  d.Erase();
+}
diff --git a/xpcom/glue/tests/gtest/TestThreadUtils.cpp b/xpcom/glue/tests/gtest/TestThreadUtils.cpp
new file mode 100644
index 0000000000..728bae612a
--- /dev/null
+++ b/xpcom/glue/tests/gtest/TestThreadUtils.cpp
@@ -0,0 +1,937 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "nsThreadUtils.h"
+#include "gtest/gtest.h"
+
+// {9e70a320-be02-11d1-8031-006008159b5a}
+#define NS_IFOO_IID \
+  {0x9e70a320, 0xbe02, 0x11d1,    \
+    {0x80, 0x31, 0x00, 0x60, 0x08, 0x15, 0x9b, 0x5a}}
+
+namespace TestThreadUtils {
+
+static bool gDebug = false;
+static int gAlive, gZombies;
+static int gAllConstructions, gConstructions, gCopyConstructions,
+           gMoveConstructions, gDestructions, gAssignments, gMoves;
+struct Spy
+{
+  static void ClearActions()
+  {
+    gAllConstructions = gConstructions = gCopyConstructions
+        = gMoveConstructions = gDestructions = gAssignments = gMoves = 0;
+  }
+  static void ClearAll()
+  {
+    ClearActions();
+    gAlive = 0;
+  }
+
+  explicit Spy(int aID) : mID(aID)
+  {
+    ++gAlive; ++gAllConstructions; ++gConstructions;
+    if (gDebug) { printf("Spy[%d@%p]()\n", mID, this); }
+  }
+  Spy(const Spy& o) : mID(o.mID)
+  {
+    ++gAlive; ++gAllConstructions; ++gCopyConstructions;
+    if (gDebug) { printf("Spy[%d@%p](&[%d@%p])\n", mID, this, o.mID, &o); }
+  }
+  Spy(Spy&& o) : mID(o.mID)
+  {
+    o.mID = -o.mID;
+    ++gZombies; ++gAllConstructions; ++gMoveConstructions;
+    if (gDebug) { printf("Spy[%d@%p](&&[%d->%d@%p])\n", mID, this, -o.mID, o.mID, &o); }
+  }
+  ~Spy()
+  {
+    if (mID >= 0) { --gAlive; } else { --gZombies; } ++gDestructions;
+    if (gDebug) { printf("~Spy[%d@%p]()\n", mID, this); }
+    mID = 0;
+  }
+  Spy& operator=(const Spy& o)
+  {
+    ++gAssignments;
+    if (gDebug) { printf("Spy[%d->%d@%p] = &[%d@%p]\n", mID, o.mID, this, o.mID, &o); }
+    mID = o.mID;
+    return *this;
+  };
+  Spy& operator=(Spy&& o)
+  {
+    --gAlive; ++gZombies;
+    ++gMoves;
+    if (gDebug) { printf("Spy[%d->%d@%p] = &&[%d->%d@%p]\n", mID, o.mID, this, o.mID, -o.mID, &o); }
+    mID = o.mID; o.mID = -o.mID;
+    return *this;
+  };
+
+  int mID; // ID given at construction, or negation if was moved from; 0 when destroyed.
+};
+
+struct ISpyWithISupports : public nsISupports
+{
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IFOO_IID)
+  NS_IMETHOD_(nsrefcnt) RefCnt() = 0;
+  NS_IMETHOD_(int32_t) ID() = 0;
+};
+NS_DEFINE_STATIC_IID_ACCESSOR(ISpyWithISupports, NS_IFOO_IID)
+struct SpyWithISupports : public ISpyWithISupports, public Spy
+{
+private:
+  virtual ~SpyWithISupports() = default;
+public:
+  explicit SpyWithISupports(int aID) : Spy(aID) {};
+  NS_DECL_ISUPPORTS
+  NS_IMETHOD_(nsrefcnt) RefCnt() override { return mRefCnt; }
+  NS_IMETHOD_(int32_t) ID() override { return mID; }
+};
+NS_IMPL_ISUPPORTS(SpyWithISupports, ISpyWithISupports)
+
+
+class IThreadUtilsObject : public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IFOO_IID)
+
+  NS_IMETHOD_(nsrefcnt) RefCnt() = 0;
+  NS_IMETHOD_(int32_t) ID() = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(IThreadUtilsObject, NS_IFOO_IID)
+
+struct ThreadUtilsObject : public IThreadUtilsObject
+{
+  // nsISupports implementation
+  NS_DECL_ISUPPORTS
+
+  // IThreadUtilsObject implementation
+  NS_IMETHOD_(nsrefcnt) RefCnt() override { return mRefCnt; }
+  NS_IMETHOD_(int32_t) ID() override { return 0; }
+
+  int mCount; // Number of calls + arguments processed.
+  int mA0, mA1, mA2, mA3;
+  Spy mSpy; const Spy* mSpyPtr;
+  ThreadUtilsObject()
+    : mCount(0)
+    , mA0(0), mA1(0), mA2(0), mA3(0)
+    , mSpy(1), mSpyPtr(nullptr)
+  {}
+private:
+  virtual ~ThreadUtilsObject() = default;
+public:
+  void Test0() { mCount += 1; }
+  void Test1i(int a0) { mCount += 2; mA0 = a0; }
+  void Test2i(int a0, int a1) { mCount += 3; mA0 = a0; mA1 = a1; }
+  void Test3i(int a0, int a1, int a2)
+  {
+    mCount += 4; mA0 = a0; mA1 = a1; mA2 = a2;
+  }
+  void Test4i(int a0, int a1, int a2, int a3)
+  {
+    mCount += 5; mA0 = a0; mA1 = a1; mA2 = a2; mA3 = a3;
+  }
+  void Test1pi(int* ap)
+  {
+    mCount += 2; mA0 = ap ? *ap : -1;
+  }
+  void Test1pci(const int* ap)
+  {
+    mCount += 2; mA0 = ap ? *ap : -1;
+  }
+  void Test1ri(int& ar)
+  {
+    mCount += 2; mA0 = ar;
+  }
+  void Test1rri(int&& arr)
+  {
+    mCount += 2; mA0 = arr;
+  }
+  void Test1upi(mozilla::UniquePtr<int> aup)
+  {
+    mCount += 2; mA0 = aup ? *aup : -1;
+  }
+  void Test1rupi(mozilla::UniquePtr<int>& aup)
+  {
+    mCount += 2; mA0 = aup ? *aup : -1;
+  }
+  void Test1rrupi(mozilla::UniquePtr<int>&& aup)
+  {
+    mCount += 2; mA0 = aup ? *aup : -1;
+  }
+
+  void Test1s(Spy) { mCount += 2; }
+  void Test1ps(Spy*) { mCount += 2; }
+  void Test1rs(Spy&) { mCount += 2; }
+  void Test1rrs(Spy&&) { mCount += 2; }
+  void Test1ups(mozilla::UniquePtr<Spy>) { mCount += 2; }
+  void Test1rups(mozilla::UniquePtr<Spy>&) { mCount += 2; }
+  void Test1rrups(mozilla::UniquePtr<Spy>&&) { mCount += 2; }
+
+  // Possible parameter passing styles:
+  void TestByValue(Spy s)
+  {
+    if (gDebug) { printf("TestByValue(Spy[%d@%p])\n", s.mID, &s); }
+    mSpy = s;
+  };
+  void TestByConstLRef(const Spy& s)
+  {
+    if (gDebug) { printf("TestByConstLRef(Spy[%d@%p]&)\n", s.mID, &s); }
+    mSpy = s;
+  };
+  void TestByRRef(Spy&& s)
+  {
+    if (gDebug) { printf("TestByRRef(Spy[%d@%p]&&)\n", s.mID, &s); }
+    mSpy = mozilla::Move(s);
+  };
+  void TestByLRef(Spy& s)
+  {
+    if (gDebug) { printf("TestByLRef(Spy[%d@%p]&)\n", s.mID, &s); }
+    mSpy = s;
+    mSpyPtr = &s;
+  };
+  void TestByPointer(Spy* p)
+  {
+    if (p) {
+      if (gDebug) { printf("TestByPointer(&Spy[%d@%p])\n", p->mID, p); }
+      mSpy = *p;
+    } else {
+      if (gDebug) { printf("TestByPointer(nullptr)\n"); }
+    }
+    mSpyPtr = p;
+  };
+  void TestByPointerToConst(const Spy* p)
+  {
+    if (p) {
+      if (gDebug) { printf("TestByPointerToConst(&Spy[%d@%p])\n", p->mID, p); }
+      mSpy = *p;
+    } else {
+      if (gDebug) { printf("TestByPointerToConst(nullptr)\n"); }
+    }
+    mSpyPtr = p;
+  };
+};
+
+NS_IMPL_ISUPPORTS(ThreadUtilsObject, IThreadUtilsObject)
+
+class ThreadUtilsRefCountedFinal final
+{
+public:
+  ThreadUtilsRefCountedFinal() : m_refCount(0) {}
+  ~ThreadUtilsRefCountedFinal() {}
+  // 'AddRef' and 'Release' methods with different return types, to verify
+  // that the return type doesn't influence storage selection.
+  long AddRef(void) { return ++m_refCount; }
+  void Release(void) { --m_refCount; }
+private:
+  long m_refCount;
+};
+
+class ThreadUtilsRefCountedBase
+{
+public:
+  ThreadUtilsRefCountedBase() : m_refCount(0) {}
+  virtual ~ThreadUtilsRefCountedBase() {}
+  // 'AddRef' and 'Release' methods with different return types, to verify
+  // that the return type doesn't influence storage selection.
+  virtual void AddRef(void) { ++m_refCount; }
+  virtual MozExternalRefCountType Release(void) { return --m_refCount; }
+private:
+  MozExternalRefCountType m_refCount;
+};
+
+class ThreadUtilsRefCountedDerived
+  : public ThreadUtilsRefCountedBase
+{};
+
+class ThreadUtilsNonRefCounted
+{};
+
+} // namespace TestThreadUtils
+
+TEST(ThreadUtils, main)
+{
+#ifndef XPCOM_GLUE_AVOID_NSPR
+  using namespace TestThreadUtils;
+
+  static_assert(!IsParameterStorageClass<int>::value,
+                "'int' should not be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByValue<int>>::value,
+                "StoreCopyPassByValue<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByConstLRef<int>>::value,
+                "StoreCopyPassByConstLRef<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByLRef<int>>::value,
+                "StoreCopyPassByLRef<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByRRef<int>>::value,
+                "StoreCopyPassByRRef<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreRefPassByLRef<int>>::value,
+                "StoreRefPassByLRef<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreConstRefPassByConstLRef<int>>::value,
+                "StoreConstRefPassByConstLRef<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StorensRefPtrPassByPtr<int>>::value,
+                "StorensRefPtrPassByPtr<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StorePtrPassByPtr<int>>::value,
+                "StorePtrPassByPtr<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreConstPtrPassByConstPtr<int>>::value,
+                "StoreConstPtrPassByConstPtr<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByConstPtr<int>>::value,
+                "StoreCopyPassByConstPtr<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByPtr<int>>::value,
+                "StoreCopyPassByPtr<int> should be recognized as Storage Class");
+
+  RefPtr<ThreadUtilsObject> rpt(new ThreadUtilsObject);
+  int count = 0;
+
+  // Test legacy functions.
+
+  nsCOMPtr<nsIRunnable> r1 =
+    NewRunnableMethod(rpt, &ThreadUtilsObject::Test0);
+  r1->Run();
+  EXPECT_EQ(count += 1, rpt->mCount);
+
+  r1 = NewRunnableMethod<int>(rpt, &ThreadUtilsObject::Test1i, 11);
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(11, rpt->mA0);
+
+  // Test variadic function with simple POD arguments.
+
+  r1 = NewRunnableMethod(rpt, &ThreadUtilsObject::Test0);
+  r1->Run();
+  EXPECT_EQ(count += 1, rpt->mCount);
+
+  static_assert(
+      mozilla::IsSame< ::detail::ParameterStorage<int>::Type,
+                      StoreCopyPassByValue<int>>::value,
+      "detail::ParameterStorage<int>::Type should be StoreCopyPassByValue<int>");
+  static_assert(
+      mozilla::IsSame< ::detail::ParameterStorage<StoreCopyPassByValue<int>>::Type,
+                      StoreCopyPassByValue<int>>::value,
+      "detail::ParameterStorage<StoreCopyPassByValue<int>>::Type should be StoreCopyPassByValue<int>");
+
+  r1 = NewRunnableMethod<int>(rpt, &ThreadUtilsObject::Test1i, 12);
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(12, rpt->mA0);
+
+  r1 = NewRunnableMethod<int, int>(
+       rpt, &ThreadUtilsObject::Test2i, 21, 22);
+  r1->Run();
+  EXPECT_EQ(count += 3, rpt->mCount);
+  EXPECT_EQ(21, rpt->mA0);
+  EXPECT_EQ(22, rpt->mA1);
+
+  r1 = NewRunnableMethod<int, int, int>(
+       rpt, &ThreadUtilsObject::Test3i, 31, 32, 33);
+  r1->Run();
+  EXPECT_EQ(count += 4, rpt->mCount);
+  EXPECT_EQ(31, rpt->mA0);
+  EXPECT_EQ(32, rpt->mA1);
+  EXPECT_EQ(33, rpt->mA2);
+
+  r1 = NewRunnableMethod<int, int, int, int>(
+       rpt, &ThreadUtilsObject::Test4i, 41, 42, 43, 44);
+  r1->Run();
+  EXPECT_EQ(count += 5, rpt->mCount);
+  EXPECT_EQ(41, rpt->mA0);
+  EXPECT_EQ(42, rpt->mA1);
+  EXPECT_EQ(43, rpt->mA2);
+  EXPECT_EQ(44, rpt->mA3);
+
+  // More interesting types of arguments.
+
+  // Passing a short to make sure forwarding works with an inexact type match.
+  short int si = 11;
+  r1 = NewRunnableMethod<int>(rpt, &ThreadUtilsObject::Test1i, si);
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(si, rpt->mA0);
+
+  // Raw pointer, possible cv-qualified.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int*>::Type,
+                                StorePtrPassByPtr<int>>::value,
+                "detail::ParameterStorage<int*>::Type should be StorePtrPassByPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int* const>::Type,
+                                StorePtrPassByPtr<int>>::value,
+                "detail::ParameterStorage<int* const>::Type should be StorePtrPassByPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int* volatile>::Type,
+                                StorePtrPassByPtr<int>>::value,
+                "detail::ParameterStorage<int* volatile>::Type should be StorePtrPassByPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int* const volatile>::Type,
+                                StorePtrPassByPtr<int>>::value,
+                "detail::ParameterStorage<int* const volatile>::Type should be StorePtrPassByPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int*>::Type::stored_type,
+                                int*>::value,
+                "detail::ParameterStorage<int*>::Type::stored_type should be int*");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int*>::Type::passed_type,
+                                int*>::value,
+                "detail::ParameterStorage<int*>::Type::passed_type should be int*");
+  {
+    int i = 12;
+    r1 = NewRunnableMethod<int*>(rpt, &ThreadUtilsObject::Test1pi, &i);
+    r1->Run();
+    EXPECT_EQ(count += 2, rpt->mCount);
+    EXPECT_EQ(i, rpt->mA0);
+  }
+
+  // Raw pointer to const.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int*>::Type,
+                                StoreConstPtrPassByConstPtr<int>>::value,
+                "detail::ParameterStorage<const int*>::Type should be StoreConstPtrPassByConstPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int* const>::Type,
+                                StoreConstPtrPassByConstPtr<int>>::value,
+                "detail::ParameterStorage<const int* const>::Type should be StoreConstPtrPassByConstPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int* volatile>::Type,
+                                StoreConstPtrPassByConstPtr<int>>::value,
+                "detail::ParameterStorage<const int* volatile>::Type should be StoreConstPtrPassByConstPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int* const volatile>::Type,
+                                StoreConstPtrPassByConstPtr<int>>::value,
+                "detail::ParameterStorage<const int* const volatile>::Type should be StoreConstPtrPassByConstPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int*>::Type::stored_type,
+                                const int*>::value,
+                "detail::ParameterStorage<const int*>::Type::stored_type should be const int*");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int*>::Type::passed_type,
+                                const int*>::value,
+                "detail::ParameterStorage<const int*>::Type::passed_type should be const int*");
+  {
+    int i = 1201;
+    r1 = NewRunnableMethod<const int*>(rpt, &ThreadUtilsObject::Test1pci, &i);
+    r1->Run();
+    EXPECT_EQ(count += 2, rpt->mCount);
+    EXPECT_EQ(i, rpt->mA0);
+  }
+
+  // Raw pointer to copy.
+  static_assert(mozilla::IsSame<StoreCopyPassByPtr<int>::stored_type,
+                                int>::value,
+                "StoreCopyPassByPtr<int>::stored_type should be int");
+  static_assert(mozilla::IsSame<StoreCopyPassByPtr<int>::passed_type,
+                                int*>::value,
+                "StoreCopyPassByPtr<int>::passed_type should be int*");
+  {
+    int i = 1202;
+    r1 = NewRunnableMethod<StoreCopyPassByPtr<int>>(
+         rpt, &ThreadUtilsObject::Test1pi, i);
+    r1->Run();
+    EXPECT_EQ(count += 2, rpt->mCount);
+    EXPECT_EQ(i, rpt->mA0);
+  }
+
+  // Raw pointer to const copy.
+  static_assert(mozilla::IsSame<StoreCopyPassByConstPtr<int>::stored_type,
+                                int>::value,
+                "StoreCopyPassByConstPtr<int>::stored_type should be int");
+  static_assert(mozilla::IsSame<StoreCopyPassByConstPtr<int>::passed_type,
+                                const int*>::value,
+                "StoreCopyPassByConstPtr<int>::passed_type should be const int*");
+  {
+    int i = 1203;
+    r1 = NewRunnableMethod<StoreCopyPassByConstPtr<int>>(
+         rpt, &ThreadUtilsObject::Test1pci, i);
+    r1->Run();
+    EXPECT_EQ(count += 2, rpt->mCount);
+    EXPECT_EQ(i, rpt->mA0);
+  }
+
+  // nsRefPtr to pointer.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<StorensRefPtrPassByPtr<SpyWithISupports>>::Type,
+                                StorensRefPtrPassByPtr<SpyWithISupports>>::value,
+                "ParameterStorage<StorensRefPtrPassByPtr<SpyWithISupports>>::Type should be StorensRefPtrPassByPtr<SpyWithISupports>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<SpyWithISupports*>::Type,
+                                StorensRefPtrPassByPtr<SpyWithISupports>>::value,
+                "ParameterStorage<SpyWithISupports*>::Type should be StorensRefPtrPassByPtr<SpyWithISupports>");
+  static_assert(mozilla::IsSame<StorensRefPtrPassByPtr<SpyWithISupports>::stored_type,
+                                RefPtr<SpyWithISupports>>::value,
+                "StorensRefPtrPassByPtr<SpyWithISupports>::stored_type should be RefPtr<SpyWithISupports>");
+  static_assert(mozilla::IsSame<StorensRefPtrPassByPtr<SpyWithISupports>::passed_type,
+                                SpyWithISupports*>::value,
+                "StorensRefPtrPassByPtr<SpyWithISupports>::passed_type should be SpyWithISupports*");
+  // (more nsRefPtr tests below)
+
+  // nsRefPtr for ref-countable classes that do not derive from ISupports.
+  static_assert(::detail::HasRefCountMethods<ThreadUtilsRefCountedFinal>::value,
+                "ThreadUtilsRefCountedFinal has AddRef() and Release()");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<ThreadUtilsRefCountedFinal*>::Type,
+                                StorensRefPtrPassByPtr<ThreadUtilsRefCountedFinal>>::value,
+                "ParameterStorage<ThreadUtilsRefCountedFinal*>::Type should be StorensRefPtrPassByPtr<ThreadUtilsRefCountedFinal>");
+  static_assert(::detail::HasRefCountMethods<ThreadUtilsRefCountedBase>::value,
+                "ThreadUtilsRefCountedBase has AddRef() and Release()");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<ThreadUtilsRefCountedBase*>::Type,
+                                StorensRefPtrPassByPtr<ThreadUtilsRefCountedBase>>::value,
+                "ParameterStorage<ThreadUtilsRefCountedBase*>::Type should be StorensRefPtrPassByPtr<ThreadUtilsRefCountedBase>");
+  static_assert(::detail::HasRefCountMethods<ThreadUtilsRefCountedDerived>::value,
+                "ThreadUtilsRefCountedDerived has AddRef() and Release()");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<ThreadUtilsRefCountedDerived*>::Type,
+                                StorensRefPtrPassByPtr<ThreadUtilsRefCountedDerived>>::value,
+                "ParameterStorage<ThreadUtilsRefCountedDerived*>::Type should be StorensRefPtrPassByPtr<ThreadUtilsRefCountedDerived>");
+
+  static_assert(!::detail::HasRefCountMethods<ThreadUtilsNonRefCounted>::value,
+                "ThreadUtilsNonRefCounted doesn't have AddRef() and Release()");
+  static_assert(!mozilla::IsSame< ::detail::ParameterStorage<ThreadUtilsNonRefCounted*>::Type,
+                                 StorensRefPtrPassByPtr<ThreadUtilsNonRefCounted>>::value,
+                "ParameterStorage<ThreadUtilsNonRefCounted*>::Type should NOT be StorensRefPtrPassByPtr<ThreadUtilsNonRefCounted>");
+
+  // Lvalue reference.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&>::Type,
+                                StoreRefPassByLRef<int>>::value,
+                "ParameterStorage<int&>::Type should be StoreRefPassByLRef<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&>::Type::stored_type,
+                                StoreRefPassByLRef<int>::stored_type>::value,
+                "ParameterStorage<int&>::Type::stored_type should be StoreRefPassByLRef<int>::stored_type");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&>::Type::stored_type,
+                                int&>::value,
+                "ParameterStorage<int&>::Type::stored_type should be int&");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&>::Type::passed_type,
+                                int&>::value,
+                "ParameterStorage<int&>::Type::passed_type should be int&");
+  {
+    int i = 13;
+    r1 = NewRunnableMethod<int&>(rpt, &ThreadUtilsObject::Test1ri, i);
+    r1->Run();
+    EXPECT_EQ(count += 2, rpt->mCount);
+    EXPECT_EQ(i, rpt->mA0);
+  }
+
+  // Rvalue reference -- Actually storing a copy and then moving it.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&&>::Type,
+                                StoreCopyPassByRRef<int>>::value,
+                "ParameterStorage<int&&>::Type should be StoreCopyPassByRRef<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&&>::Type::stored_type,
+                                StoreCopyPassByRRef<int>::stored_type>::value,
+                "ParameterStorage<int&&>::Type::stored_type should be StoreCopyPassByRRef<int>::stored_type");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&&>::Type::stored_type,
+                                int>::value,
+                "ParameterStorage<int&&>::Type::stored_type should be int");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&&>::Type::passed_type,
+                                int&&>::value,
+                "ParameterStorage<int&&>::Type::passed_type should be int&&");
+  {
+    int i = 14;
+    r1 = NewRunnableMethod<int&&>(
+          rpt, &ThreadUtilsObject::Test1rri, mozilla::Move(i));
+  }
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(14, rpt->mA0);
+
+  // Null unique pointer, by semi-implicit store&move with "T&&" syntax.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<mozilla::UniquePtr<int>&&>::Type,
+                                StoreCopyPassByRRef<mozilla::UniquePtr<int>>>::value,
+                "ParameterStorage<UniquePtr<int>&&>::Type should be StoreCopyPassByRRef<UniquePtr<int>>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<mozilla::UniquePtr<int>&&>::Type::stored_type,
+                                StoreCopyPassByRRef<mozilla::UniquePtr<int>>::stored_type>::value,
+                "ParameterStorage<UniquePtr<int>&&>::Type::stored_type should be StoreCopyPassByRRef<UniquePtr<int>>::stored_type");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<mozilla::UniquePtr<int>&&>::Type::stored_type,
+                                mozilla::UniquePtr<int>>::value,
+                "ParameterStorage<UniquePtr<int>&&>::Type::stored_type should be UniquePtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<mozilla::UniquePtr<int>&&>::Type::passed_type,
+                                mozilla::UniquePtr<int>&&>::value,
+                "ParameterStorage<UniquePtr<int>&&>::Type::passed_type should be UniquePtr<int>&&");
+  {
+    mozilla::UniquePtr<int> upi;
+    r1 = NewRunnableMethod<mozilla::UniquePtr<int>&&>(
+          rpt, &ThreadUtilsObject::Test1upi, mozilla::Move(upi));
+  }
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(-1, rpt->mA0);
+  rpt->mA0 = 0;
+
+  // Null unique pointer, by explicit store&move with "StoreCopyPassByRRef<T>" syntax.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<StoreCopyPassByRRef<mozilla::UniquePtr<int>>>::Type::stored_type,
+                                StoreCopyPassByRRef<mozilla::UniquePtr<int>>::stored_type>::value,
+                "ParameterStorage<StoreCopyPassByRRef<UniquePtr<int>>>::Type::stored_type should be StoreCopyPassByRRef<UniquePtr<int>>::stored_type");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<StoreCopyPassByRRef<mozilla::UniquePtr<int>>>::Type::stored_type,
+                                StoreCopyPassByRRef<mozilla::UniquePtr<int>>::stored_type>::value,
+                "ParameterStorage<StoreCopyPassByRRef<UniquePtr<int>>>::Type::stored_type should be StoreCopyPassByRRef<UniquePtr<int>>::stored_type");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<StoreCopyPassByRRef<mozilla::UniquePtr<int>>>::Type::stored_type,
+                                mozilla::UniquePtr<int>>::value,
+                "ParameterStorage<StoreCopyPassByRRef<UniquePtr<int>>>::Type::stored_type should be UniquePtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<StoreCopyPassByRRef<mozilla::UniquePtr<int>>>::Type::passed_type,
+                                mozilla::UniquePtr<int>&&>::value,
+                "ParameterStorage<StoreCopyPassByRRef<UniquePtr<int>>>::Type::passed_type should be UniquePtr<int>&&");
+  {
+    mozilla::UniquePtr<int> upi;
+    r1 = NewRunnableMethod
+         <StoreCopyPassByRRef<mozilla::UniquePtr<int>>>(
+           rpt, &ThreadUtilsObject::Test1upi, mozilla::Move(upi));
+  }
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(-1, rpt->mA0);
+
+  // Unique pointer as xvalue.
+  {
+    mozilla::UniquePtr<int> upi = mozilla::MakeUnique<int>(1);
+    r1 = NewRunnableMethod<mozilla::UniquePtr<int>&&>(
+           rpt, &ThreadUtilsObject::Test1upi, mozilla::Move(upi));
+  }
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(1, rpt->mA0);
+
+  {
+    mozilla::UniquePtr<int> upi = mozilla::MakeUnique<int>(1);
+    r1 = NewRunnableMethod
+         <StoreCopyPassByRRef<mozilla::UniquePtr<int>>>
+         (rpt, &ThreadUtilsObject::Test1upi, mozilla::Move(upi));
+  }
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(1, rpt->mA0);
+
+  // Unique pointer as prvalue.
+  r1 = NewRunnableMethod<mozilla::UniquePtr<int>&&>(
+         rpt, &ThreadUtilsObject::Test1upi, mozilla::MakeUnique<int>(2));
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(2, rpt->mA0);
+
+  // Unique pointer as lvalue to lref.
+  {
+    mozilla::UniquePtr<int> upi;
+    r1 = NewRunnableMethod<mozilla::UniquePtr<int>&>(
+           rpt, &ThreadUtilsObject::Test1rupi, upi);
+    // Passed as lref, so Run() must be called while local upi is still alive!
+    r1->Run();
+  }
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(-1, rpt->mA0);
+
+  // Verify copy/move assumptions.
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from lvalue, pass by value\n", __LINE__); }
+  { // Block around nsCOMPtr lifetime.
+    nsCOMPtr<nsIRunnable> r2;
+    { // Block around Spy lifetime.
+      if (gDebug) { printf("%d - Spy s(10)\n", __LINE__); }
+      Spy s(10);
+      EXPECT_EQ(1, gConstructions);
+      EXPECT_EQ(1, gAlive);
+      if (gDebug) { printf("%d - r2 = NewRunnableMethod<StoreCopyPassByValue<Spy>>(&TestByValue, s)\n", __LINE__); }
+      r2 = NewRunnableMethod<StoreCopyPassByValue<Spy>>(
+           rpt, &ThreadUtilsObject::TestByValue, s);
+      EXPECT_EQ(2, gAlive);
+      EXPECT_LE(1, gCopyConstructions); // At least 1 copy-construction.
+      Spy::ClearActions();
+      if (gDebug) { printf("%d - End block with Spy s(10)\n", __LINE__); }
+    }
+    EXPECT_EQ(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r2->Run();
+    EXPECT_LE(1, gCopyConstructions); // Another copy-construction in call.
+    EXPECT_EQ(10, rpt->mSpy.mID);
+    EXPECT_LE(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from prvalue, pass by value\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - r3 = NewRunnableMethod<StoreCopyPassByValue<Spy>>(&TestByValue, Spy(11))\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r3 =
+      NewRunnableMethod<StoreCopyPassByValue<Spy>>(
+        rpt, &ThreadUtilsObject::TestByValue, Spy(11));
+    EXPECT_EQ(1, gAlive);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_LE(1, gMoveConstructions);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r3->Run();
+    EXPECT_LE(1, gCopyConstructions); // Another copy-construction in call.
+    EXPECT_EQ(11, rpt->mSpy.mID);
+    EXPECT_LE(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  { // Store copy from xvalue, pass by value.
+    nsCOMPtr<nsIRunnable> r4;
+    {
+      Spy s(12);
+      EXPECT_EQ(1, gConstructions);
+      EXPECT_EQ(1, gAlive);
+      Spy::ClearActions();
+      r4 = NewRunnableMethod<StoreCopyPassByValue<Spy>>(
+          rpt, &ThreadUtilsObject::TestByValue, mozilla::Move(s));
+      EXPECT_LE(1, gMoveConstructions);
+      EXPECT_EQ(1, gAlive);
+      EXPECT_EQ(1, gZombies);
+      Spy::ClearActions();
+    }
+    EXPECT_EQ(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    EXPECT_EQ(0, gZombies);
+    Spy::ClearActions();
+    r4->Run();
+    EXPECT_LE(1, gCopyConstructions); // Another copy-construction in call.
+    EXPECT_EQ(12, rpt->mSpy.mID);
+    EXPECT_LE(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+  }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+  // Won't test xvalues anymore, prvalues are enough to verify all rvalues.
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from lvalue, pass by const lvalue ref\n", __LINE__); }
+  { // Block around nsCOMPtr lifetime.
+    nsCOMPtr<nsIRunnable> r5;
+    { // Block around Spy lifetime.
+      if (gDebug) { printf("%d - Spy s(20)\n", __LINE__); }
+      Spy s(20);
+      EXPECT_EQ(1, gConstructions);
+      EXPECT_EQ(1, gAlive);
+      if (gDebug) { printf("%d - r5 = NewRunnableMethod<StoreCopyPassByConstLRef<Spy>>(&TestByConstLRef, s)\n", __LINE__); }
+      r5 = NewRunnableMethod<StoreCopyPassByConstLRef<Spy>>(
+           rpt, &ThreadUtilsObject::TestByConstLRef, s);
+      EXPECT_EQ(2, gAlive);
+      EXPECT_LE(1, gCopyConstructions); // At least 1 copy-construction.
+      Spy::ClearActions();
+      if (gDebug) { printf("%d - End block with Spy s(20)\n", __LINE__); }
+    }
+    EXPECT_EQ(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r5->Run();
+    EXPECT_EQ(0, gCopyConstructions); // No copies in call.
+    EXPECT_EQ(20, rpt->mSpy.mID);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from prvalue, pass by const lvalue ref\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - r6 = NewRunnableMethod<StoreCopyPassByConstLRef<Spy>>(&TestByConstLRef, Spy(21))\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r6 =
+      NewRunnableMethod<StoreCopyPassByConstLRef<Spy>>(
+        rpt, &ThreadUtilsObject::TestByConstLRef, Spy(21));
+    EXPECT_EQ(1, gAlive);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_LE(1, gMoveConstructions);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r6->Run();
+    EXPECT_EQ(0, gCopyConstructions); // No copies in call.
+    EXPECT_EQ(21, rpt->mSpy.mID);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from lvalue, pass by rvalue ref\n", __LINE__); }
+  { // Block around nsCOMPtr lifetime.
+    nsCOMPtr<nsIRunnable> r7;
+    { // Block around Spy lifetime.
+      if (gDebug) { printf("%d - Spy s(30)\n", __LINE__); }
+      Spy s(30);
+      EXPECT_EQ(1, gConstructions);
+      EXPECT_EQ(1, gAlive);
+      if (gDebug) { printf("%d - r7 = NewRunnableMethod<StoreCopyPassByRRef<Spy>>(&TestByRRef, s)\n", __LINE__); }
+      r7 = NewRunnableMethod<StoreCopyPassByRRef<Spy>>(
+           rpt, &ThreadUtilsObject::TestByRRef, s);
+      EXPECT_EQ(2, gAlive);
+      EXPECT_LE(1, gCopyConstructions); // At least 1 copy-construction.
+      Spy::ClearActions();
+      if (gDebug) { printf("%d - End block with Spy s(30)\n", __LINE__); }
+    }
+    EXPECT_EQ(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r7->Run();
+    EXPECT_LE(1, gMoves); // Move in call.
+    EXPECT_EQ(30, rpt->mSpy.mID);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(0, gAlive); // Spy inside Test is not counted.
+    EXPECT_EQ(1, gZombies); // Our local spy should now be a zombie.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from prvalue, pass by rvalue ref\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - r8 = NewRunnableMethod<StoreCopyPassByRRef<Spy>>(&TestByRRef, Spy(31))\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r8 =
+      NewRunnableMethod<StoreCopyPassByRRef<Spy>>(
+        rpt, &ThreadUtilsObject::TestByRRef, Spy(31));
+    EXPECT_EQ(1, gAlive);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_LE(1, gMoveConstructions);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r8->Run();
+    EXPECT_LE(1, gMoves); // Move in call.
+    EXPECT_EQ(31, rpt->mSpy.mID);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(0, gAlive); // Spy inside Test is not counted.
+    EXPECT_EQ(1, gZombies); // Our local spy should now be a zombie.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store lvalue ref, pass lvalue ref\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - Spy s(40)\n", __LINE__); }
+    Spy s(40);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - r9 = NewRunnableMethod<Spy&>(&TestByLRef, s)\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r9 =
+      NewRunnableMethod<Spy&>(
+        rpt, &ThreadUtilsObject::TestByLRef, s);
+    EXPECT_EQ(0, gAllConstructions);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r9->Run();
+    EXPECT_LE(1, gAssignments); // Assignment from reference in call.
+    EXPECT_EQ(40, rpt->mSpy.mID);
+    EXPECT_EQ(&s, rpt->mSpyPtr);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive); // Spy inside Test is not counted.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store nsRefPtr, pass by pointer\n", __LINE__); }
+  { // Block around nsCOMPtr lifetime.
+    nsCOMPtr<nsIRunnable> r10;
+    SpyWithISupports* ptr = 0;
+    { // Block around RefPtr<Spy> lifetime.
+      if (gDebug) { printf("%d - RefPtr<SpyWithISupports> s(new SpyWithISupports(45))\n", __LINE__); }
+      RefPtr<SpyWithISupports> s(new SpyWithISupports(45));
+      ptr = s.get();
+      EXPECT_EQ(1, gConstructions);
+      EXPECT_EQ(1, gAlive);
+      if (gDebug) { printf("%d - r10 = NewRunnableMethod<StorensRefPtrPassByPtr<Spy>>(&TestByRRef, s.get())\n", __LINE__); }
+      r10 = NewRunnableMethod<StorensRefPtrPassByPtr<SpyWithISupports>>(
+            rpt, &ThreadUtilsObject::TestByPointer, s.get());
+      EXPECT_LE(0, gAllConstructions);
+      EXPECT_EQ(1, gAlive);
+      Spy::ClearActions();
+      if (gDebug) { printf("%d - End block with RefPtr<Spy> s\n", __LINE__); }
+    }
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r10->Run();
+    EXPECT_LE(1, gAssignments); // Assignment from pointee in call.
+    EXPECT_EQ(45, rpt->mSpy.mID);
+    EXPECT_EQ(ptr, rpt->mSpyPtr);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive); // Spy inside Test is not counted.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store pointer to lvalue, pass by pointer\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - Spy s(55)\n", __LINE__); }
+    Spy s(55);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - r11 = NewRunnableMethod<Spy*>(&TestByPointer, s)\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r11 =
+      NewRunnableMethod<Spy*>(
+        rpt, &ThreadUtilsObject::TestByPointer, &s);
+    EXPECT_EQ(0, gAllConstructions);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r11->Run();
+    EXPECT_LE(1, gAssignments); // Assignment from pointee in call.
+    EXPECT_EQ(55, rpt->mSpy.mID);
+    EXPECT_EQ(&s, rpt->mSpyPtr);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive); // Spy inside Test is not counted.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store pointer to const lvalue, pass by pointer\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - Spy s(60)\n", __LINE__); }
+    Spy s(60);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - r12 = NewRunnableMethod<Spy*>(&TestByPointer, s)\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r12 =
+      NewRunnableMethod<const Spy*>(
+        rpt, &ThreadUtilsObject::TestByPointerToConst, &s);
+    EXPECT_EQ(0, gAllConstructions);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r12->Run();
+    EXPECT_LE(1, gAssignments); // Assignment from pointee in call.
+    EXPECT_EQ(60, rpt->mSpy.mID);
+    EXPECT_EQ(&s, rpt->mSpyPtr);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive); // Spy inside Test is not counted.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+#endif // XPCOM_GLUE_AVOID_NSPR
+}
diff --git a/xpcom/glue/tests/gtest/moz.build b/xpcom/glue/tests/gtest/moz.build
new file mode 100644
index 0000000000..9f4d83a3e9
--- /dev/null
+++ b/xpcom/glue/tests/gtest/moz.build
@@ -0,0 +1,22 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+UNIFIED_SOURCES += [
+    'TestArray.cpp',
+    'TestFileUtils.cpp',
+    'TestGCPostBarriers.cpp',
+    'TestNsDeque.cpp',
+    'TestThreadUtils.cpp',
+]
+
+LOCAL_INCLUDES = [
+    '../..',
+]
+
+FINAL_LIBRARY = 'xul-gtest'
+
+if CONFIG['GNU_CXX']:
+    CXXFLAGS += ['-Wno-error=shadow']