Add m-esr52 at 52.6.0

1 files changed, 4079 insertions, 0 deletions

diff --git a/dom/base/nsObjectLoadingContent.cpp b/dom/base/nsObjectLoadingContent.cpp
new file mode 100644
index 0000000000..9e9dacf014
--- /dev/null
+++ b/dom/base/nsObjectLoadingContent.cpp
@@ -0,0 +1,4079 @@
+/* -*- 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/. */
+/*
+ * A base class implementing nsIObjectLoadingContent for use by
+ * various content nodes that want to provide plugin/document/image
+ * loading functionality (eg <embed>, <object>, <applet>, etc).
+ */
+
+// Interface headers
+#include "imgLoader.h"
+#include "nsIConsoleService.h"
+#include "nsIContent.h"
+#include "nsIContentInlines.h"
+#include "nsIDocShell.h"
+#include "nsIDocument.h"
+#include "nsIDOMCustomEvent.h"
+#include "nsIDOMDocument.h"
+#include "nsIDOMHTMLObjectElement.h"
+#include "nsIDOMHTMLAppletElement.h"
+#include "nsIExternalProtocolHandler.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsIObjectFrame.h"
+#include "nsIPermissionManager.h"
+#include "nsPluginHost.h"
+#include "nsPluginInstanceOwner.h"
+#include "nsJSNPRuntime.h"
+#include "nsINestedURI.h"
+#include "nsIPresShell.h"
+#include "nsScriptSecurityManager.h"
+#include "nsIScriptSecurityManager.h"
+#include "nsIStreamConverterService.h"
+#include "nsIURILoader.h"
+#include "nsIURL.h"
+#include "nsIWebNavigation.h"
+#include "nsIWebNavigationInfo.h"
+#include "nsIScriptChannel.h"
+#include "nsIBlocklistService.h"
+#include "nsIAsyncVerifyRedirectCallback.h"
+#include "nsIAppShell.h"
+#include "nsIXULRuntime.h"
+#include "nsIScriptError.h"
+
+#include "nsError.h"
+
+// Util headers
+#include "prenv.h"
+#include "mozilla/Logging.h"
+
+#include "nsCURILoader.h"
+#include "nsContentPolicyUtils.h"
+#include "nsContentUtils.h"
+#include "nsDocShellCID.h"
+#include "nsGkAtoms.h"
+#include "nsThreadUtils.h"
+#include "nsNetUtil.h"
+#include "nsMimeTypes.h"
+#include "nsStyleUtil.h"
+#include "nsUnicharUtils.h"
+#include "mozilla/Preferences.h"
+#include "nsSandboxFlags.h"
+
+// Concrete classes
+#include "nsFrameLoader.h"
+
+#include "nsObjectLoadingContent.h"
+#include "mozAutoDocUpdate.h"
+#include "nsIContentSecurityPolicy.h"
+#include "GeckoProfiler.h"
+#include "nsPluginFrame.h"
+#include "nsDOMClassInfo.h"
+#include "nsWrapperCacheInlines.h"
+#include "nsDOMJSUtils.h"
+
+#include "nsWidgetsCID.h"
+#include "nsContentCID.h"
+#include "mozilla/BasicEvents.h"
+#include "mozilla/dom/BindingUtils.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/PluginCrashedEvent.h"
+#include "mozilla/AsyncEventDispatcher.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/EventStates.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/dom/HTMLObjectElementBinding.h"
+#include "mozilla/dom/HTMLSharedObjectElement.h"
+#include "nsChannelClassifier.h"
+
+#ifdef XP_WIN
+// Thanks so much, Microsoft! :(
+#ifdef CreateEvent
+#undef CreateEvent
+#endif
+#endif // XP_WIN
+
+#ifdef XP_MACOSX
+// HandlePluginCrashed() and HandlePluginInstantiated() needed from here to
+// fix bug 1147521.  Should later be replaced by proper interface methods,
+// maybe on nsIObjectLoadingContext.
+#include "mozilla/dom/HTMLObjectElement.h"
+#endif
+
+static NS_DEFINE_CID(kAppShellCID, NS_APPSHELL_CID);
+
+static const char *kPrefJavaMIME = "plugin.java.mime";
+static const char *kPrefYoutubeRewrite = "plugins.rewrite_youtube_embeds";
+static const char *kPrefBlockURIs = "browser.safebrowsing.blockedURIs.enabled";
+static const char *kPrefFavorFallbackMode = "plugins.favorfallback.mode";
+static const char *kPrefFavorFallbackRules = "plugins.favorfallback.rules";
+
+using namespace mozilla;
+using namespace mozilla::dom;
+using namespace mozilla::net;
+
+static LogModule*
+GetObjectLog()
+{
+  static LazyLogModule sLog("objlc");
+  return sLog;
+}
+
+#define LOG(args) MOZ_LOG(GetObjectLog(), mozilla::LogLevel::Debug, args)
+#define LOG_ENABLED() MOZ_LOG_TEST(GetObjectLog(), mozilla::LogLevel::Debug)
+
+static bool
+IsJavaMIME(const nsACString & aMIMEType)
+{
+  return
+    nsPluginHost::GetSpecialType(aMIMEType) == nsPluginHost::eSpecialType_Java;
+}
+
+static bool
+IsFlashMIME(const nsACString & aMIMEType)
+{
+  return
+    nsPluginHost::GetSpecialType(aMIMEType) == nsPluginHost::eSpecialType_Flash;
+}
+
+static bool
+InActiveDocument(nsIContent *aContent)
+{
+  if (!aContent->IsInComposedDoc()) {
+    return false;
+  }
+  nsIDocument *doc = aContent->OwnerDoc();
+  return (doc && doc->IsActive());
+}
+
+///
+/// Runnables and helper classes
+///
+
+class nsAsyncInstantiateEvent : public Runnable {
+public:
+  explicit nsAsyncInstantiateEvent(nsObjectLoadingContent* aContent)
+  : mContent(aContent) {}
+
+  ~nsAsyncInstantiateEvent() {}
+
+  NS_IMETHOD Run();
+
+private:
+  nsCOMPtr<nsIObjectLoadingContent> mContent;
+};
+
+NS_IMETHODIMP
+nsAsyncInstantiateEvent::Run()
+{
+  nsObjectLoadingContent *objLC =
+    static_cast<nsObjectLoadingContent *>(mContent.get());
+
+  // If objLC is no longer tracking this event, we've been canceled or
+  // superseded
+  if (objLC->mPendingInstantiateEvent != this) {
+    return NS_OK;
+  }
+  objLC->mPendingInstantiateEvent = nullptr;
+
+  return objLC->SyncStartPluginInstance();
+}
+
+// Checks to see if the content for a plugin instance should be unloaded
+// (outside an active document) or stopped (in a document but unrendered). This
+// is used to allow scripts to move a plugin around the document hierarchy
+// without re-instantiating it.
+class CheckPluginStopEvent : public Runnable {
+public:
+  explicit CheckPluginStopEvent(nsObjectLoadingContent* aContent)
+  : mContent(aContent) {}
+
+  ~CheckPluginStopEvent() {}
+
+  NS_IMETHOD Run();
+
+private:
+  nsCOMPtr<nsIObjectLoadingContent> mContent;
+};
+
+NS_IMETHODIMP
+CheckPluginStopEvent::Run()
+{
+  nsObjectLoadingContent *objLC =
+    static_cast<nsObjectLoadingContent *>(mContent.get());
+
+  // If objLC is no longer tracking this event, we've been canceled or
+  // superseded. We clear this before we finish - either by calling
+  // UnloadObject/StopPluginInstance, or directly if we took no action.
+  if (objLC->mPendingCheckPluginStopEvent != this) {
+    return NS_OK;
+  }
+
+  // CheckPluginStopEvent is queued when we either lose our frame, are removed
+  // from the document, or the document goes inactive. To avoid stopping the
+  // plugin when script is reparenting us or layout is rebuilding, we wait until
+  // this event to decide to stop.
+
+  nsCOMPtr<nsIContent> content =
+    do_QueryInterface(static_cast<nsIImageLoadingContent *>(objLC));
+  if (!InActiveDocument(content)) {
+    LOG(("OBJLC [%p]: Unloading plugin outside of document", this));
+    objLC->StopPluginInstance();
+    return NS_OK;
+  }
+
+  if (content->GetPrimaryFrame()) {
+    LOG(("OBJLC [%p]: CheckPluginStopEvent - in active document with frame"
+         ", no action", this));
+    objLC->mPendingCheckPluginStopEvent = nullptr;
+    return NS_OK;
+  }
+
+  // In an active document, but still no frame. Flush layout to see if we can
+  // regain a frame now.
+  LOG(("OBJLC [%p]: CheckPluginStopEvent - No frame, flushing layout", this));
+  nsIDocument* composedDoc = content->GetComposedDoc();
+  if (composedDoc) {
+    composedDoc->FlushPendingNotifications(Flush_Layout);
+    if (objLC->mPendingCheckPluginStopEvent != this) {
+      LOG(("OBJLC [%p]: CheckPluginStopEvent - superseded in layout flush",
+           this));
+      return NS_OK;
+    } else if (content->GetPrimaryFrame()) {
+      LOG(("OBJLC [%p]: CheckPluginStopEvent - frame gained in layout flush",
+           this));
+      objLC->mPendingCheckPluginStopEvent = nullptr;
+      return NS_OK;
+    }
+  }
+
+  // Still no frame, suspend plugin. HasNewFrame will restart us when we
+  // become rendered again
+  LOG(("OBJLC [%p]: Stopping plugin that lost frame", this));
+  objLC->StopPluginInstance();
+
+  return NS_OK;
+}
+
+/**
+ * Helper task for firing simple events
+ */
+class nsSimplePluginEvent : public Runnable {
+public:
+  nsSimplePluginEvent(nsIContent* aTarget, const nsAString &aEvent)
+    : mTarget(aTarget)
+    , mDocument(aTarget->GetComposedDoc())
+    , mEvent(aEvent)
+  {
+    MOZ_ASSERT(aTarget && mDocument);
+  }
+
+  nsSimplePluginEvent(nsIDocument* aTarget, const nsAString& aEvent)
+    : mTarget(aTarget)
+    , mDocument(aTarget)
+    , mEvent(aEvent)
+  {
+    MOZ_ASSERT(aTarget);
+  }
+
+  nsSimplePluginEvent(nsIContent* aTarget,
+                      nsIDocument* aDocument,
+                      const nsAString& aEvent)
+    : mTarget(aTarget)
+    , mDocument(aDocument)
+    , mEvent(aEvent)
+  {
+    MOZ_ASSERT(aTarget && aDocument);
+  }
+
+  ~nsSimplePluginEvent() {}
+
+  NS_IMETHOD Run();
+
+private:
+  nsCOMPtr<nsISupports> mTarget;
+  nsCOMPtr<nsIDocument> mDocument;
+  nsString mEvent;
+};
+
+NS_IMETHODIMP
+nsSimplePluginEvent::Run()
+{
+  if (mDocument && mDocument->IsActive()) {
+    LOG(("OBJLC [%p]: nsSimplePluginEvent firing event \"%s\"", mTarget.get(),
+         NS_ConvertUTF16toUTF8(mEvent).get()));
+    nsContentUtils::DispatchTrustedEvent(mDocument, mTarget,
+                                         mEvent, true, true);
+  }
+  return NS_OK;
+}
+
+/**
+ * A task for firing PluginCrashed DOM Events.
+ */
+class nsPluginCrashedEvent : public Runnable {
+public:
+  nsCOMPtr<nsIContent> mContent;
+  nsString mPluginDumpID;
+  nsString mBrowserDumpID;
+  nsString mPluginName;
+  nsString mPluginFilename;
+  bool mSubmittedCrashReport;
+
+  nsPluginCrashedEvent(nsIContent* aContent,
+                       const nsAString& aPluginDumpID,
+                       const nsAString& aBrowserDumpID,
+                       const nsAString& aPluginName,
+                       const nsAString& aPluginFilename,
+                       bool submittedCrashReport)
+    : mContent(aContent),
+      mPluginDumpID(aPluginDumpID),
+      mBrowserDumpID(aBrowserDumpID),
+      mPluginName(aPluginName),
+      mPluginFilename(aPluginFilename),
+      mSubmittedCrashReport(submittedCrashReport)
+  {}
+
+  ~nsPluginCrashedEvent() {}
+
+  NS_IMETHOD Run();
+};
+
+NS_IMETHODIMP
+nsPluginCrashedEvent::Run()
+{
+  LOG(("OBJLC [%p]: Firing plugin crashed event\n",
+       mContent.get()));
+
+  nsCOMPtr<nsIDocument> doc = mContent->GetComposedDoc();
+  if (!doc) {
+    NS_WARNING("Couldn't get document for PluginCrashed event!");
+    return NS_OK;
+  }
+
+  PluginCrashedEventInit init;
+  init.mPluginDumpID = mPluginDumpID;
+  init.mBrowserDumpID = mBrowserDumpID;
+  init.mPluginName = mPluginName;
+  init.mPluginFilename = mPluginFilename;
+  init.mSubmittedCrashReport = mSubmittedCrashReport;
+  init.mBubbles = true;
+  init.mCancelable = true;
+
+  RefPtr<PluginCrashedEvent> event =
+    PluginCrashedEvent::Constructor(doc, NS_LITERAL_STRING("PluginCrashed"), init);
+
+  event->SetTrusted(true);
+  event->WidgetEventPtr()->mFlags.mOnlyChromeDispatch = true;
+
+  EventDispatcher::DispatchDOMEvent(mContent, nullptr, event, nullptr, nullptr);
+  return NS_OK;
+}
+
+class nsStopPluginRunnable : public Runnable, public nsITimerCallback
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+
+  nsStopPluginRunnable(nsPluginInstanceOwner* aInstanceOwner,
+                       nsObjectLoadingContent* aContent)
+    : mInstanceOwner(aInstanceOwner)
+    , mContent(aContent)
+  {
+    NS_ASSERTION(aInstanceOwner, "need an owner");
+    NS_ASSERTION(aContent, "need a nsObjectLoadingContent");
+  }
+
+  // Runnable
+  NS_IMETHOD Run() override;
+
+  // nsITimerCallback
+  NS_IMETHOD Notify(nsITimer* timer) override;
+
+protected:
+  virtual ~nsStopPluginRunnable() {}
+
+private:
+  nsCOMPtr<nsITimer> mTimer;
+  RefPtr<nsPluginInstanceOwner> mInstanceOwner;
+  nsCOMPtr<nsIObjectLoadingContent> mContent;
+};
+
+NS_IMPL_ISUPPORTS_INHERITED(nsStopPluginRunnable, Runnable, nsITimerCallback)
+
+NS_IMETHODIMP
+nsStopPluginRunnable::Notify(nsITimer *aTimer)
+{
+  return Run();
+}
+
+NS_IMETHODIMP
+nsStopPluginRunnable::Run()
+{
+  // InitWithCallback calls Release before AddRef so we need to hold a
+  // strong ref on 'this' since we fall through to this scope if it fails.
+  nsCOMPtr<nsITimerCallback> kungFuDeathGrip = this;
+  nsCOMPtr<nsIAppShell> appShell = do_GetService(kAppShellCID);
+  if (appShell) {
+    uint32_t currentLevel = 0;
+    appShell->GetEventloopNestingLevel(&currentLevel);
+    if (currentLevel > mInstanceOwner->GetLastEventloopNestingLevel()) {
+      if (!mTimer)
+        mTimer = do_CreateInstance("@mozilla.org/timer;1");
+      if (mTimer) {
+        // Fire 100ms timer to try to tear down this plugin as quickly as
+        // possible once the nesting level comes back down.
+        nsresult rv = mTimer->InitWithCallback(this, 100,
+                                               nsITimer::TYPE_ONE_SHOT);
+        if (NS_SUCCEEDED(rv)) {
+          return rv;
+        }
+      }
+      NS_ERROR("Failed to setup a timer to stop the plugin later (at a safe "
+               "time). Stopping the plugin now, this might crash.");
+    }
+  }
+
+  mTimer = nullptr;
+
+  static_cast<nsObjectLoadingContent*>(mContent.get())->
+    DoStopPlugin(mInstanceOwner, false, true);
+
+  return NS_OK;
+}
+
+// You can't take the address of bitfield members, so we have two separate
+// classes for these :-/
+
+// Sets a object's mInstantiating bit to false when destroyed
+class AutoSetInstantiatingToFalse {
+public:
+  explicit AutoSetInstantiatingToFalse(nsObjectLoadingContent* aContent)
+    : mContent(aContent) {}
+  ~AutoSetInstantiatingToFalse() { mContent->mInstantiating = false; }
+private:
+  nsObjectLoadingContent* mContent;
+};
+
+// Sets a object's mInstantiating bit to false when destroyed
+class AutoSetLoadingToFalse {
+public:
+  explicit AutoSetLoadingToFalse(nsObjectLoadingContent* aContent)
+    : mContent(aContent) {}
+  ~AutoSetLoadingToFalse() { mContent->mIsLoading = false; }
+private:
+  nsObjectLoadingContent* mContent;
+};
+
+///
+/// Helper functions
+///
+
+static bool
+IsSuccessfulRequest(nsIRequest* aRequest, nsresult* aStatus)
+{
+  nsresult rv = aRequest->GetStatus(aStatus);
+  if (NS_FAILED(rv) || NS_FAILED(*aStatus)) {
+    return false;
+  }
+
+  // This may still be an error page or somesuch
+  nsCOMPtr<nsIHttpChannel> httpChan(do_QueryInterface(aRequest));
+  if (httpChan) {
+    bool success;
+    rv = httpChan->GetRequestSucceeded(&success);
+    if (NS_FAILED(rv) || !success) {
+      return false;
+    }
+  }
+
+  // Otherwise, the request is successful
+  return true;
+}
+
+static bool
+CanHandleURI(nsIURI* aURI)
+{
+  nsAutoCString scheme;
+  if (NS_FAILED(aURI->GetScheme(scheme))) {
+    return false;
+  }
+
+  nsIIOService* ios = nsContentUtils::GetIOService();
+  if (!ios)
+    return false;
+
+  nsCOMPtr<nsIProtocolHandler> handler;
+  ios->GetProtocolHandler(scheme.get(), getter_AddRefs(handler));
+  if (!handler) {
+    return false;
+  }
+
+  nsCOMPtr<nsIExternalProtocolHandler> extHandler =
+    do_QueryInterface(handler);
+  // We can handle this URI if its protocol handler is not the external one
+  return extHandler == nullptr;
+}
+
+// Helper for tedious URI equality syntax when one or both arguments may be
+// null and URIEquals(null, null) should be true
+static bool inline
+URIEquals(nsIURI *a, nsIURI *b)
+{
+  bool equal;
+  return (!a && !b) || (a && b && NS_SUCCEEDED(a->Equals(b, &equal)) && equal);
+}
+
+static bool
+IsSupportedImage(const nsCString& aMimeType)
+{
+  return imgLoader::SupportImageWithMimeType(aMimeType.get());
+}
+
+static void
+GetExtensionFromURI(nsIURI* uri, nsCString& ext)
+{
+  nsCOMPtr<nsIURL> url(do_QueryInterface(uri));
+  if (url) {
+    url->GetFileExtension(ext);
+  } else {
+    nsCString spec;
+    nsresult rv = uri->GetSpec(spec);
+    if (NS_FAILED(rv)) {
+      // This means we could incorrectly think a plugin is not enabled for
+      // the URI when it is, but that's not so bad.
+      ext.Truncate();
+      return;
+    }
+
+    int32_t offset = spec.RFindChar('.');
+    if (offset != kNotFound) {
+      ext = Substring(spec, offset + 1, spec.Length());
+    }
+  }
+}
+
+/**
+ * Checks whether a plugin exists and is enabled for the extension
+ * in the given URI. The MIME type is returned in the mimeType out parameter.
+ */
+bool
+IsPluginEnabledByExtension(nsIURI* uri, nsCString& mimeType)
+{
+  nsAutoCString ext;
+  GetExtensionFromURI(uri, ext);
+
+  if (ext.IsEmpty()) {
+    return false;
+  }
+
+  // Disables any native PDF plugins, when internal PDF viewer is enabled.
+  if (ext.EqualsIgnoreCase("pdf") && nsContentUtils::IsPDFJSEnabled()) {
+    return false;
+  }
+
+  // Disables any native SWF plugins, when internal SWF player is enabled.
+  if (ext.EqualsIgnoreCase("swf") && nsContentUtils::IsSWFPlayerEnabled()) {
+    return false;
+  }
+
+  RefPtr<nsPluginHost> pluginHost = nsPluginHost::GetInst();
+
+  if (!pluginHost) {
+    NS_NOTREACHED("No pluginhost");
+    return false;
+  }
+
+  return pluginHost->HavePluginForExtension(ext, mimeType);
+}
+
+///
+/// Member Functions
+///
+
+// Helper to queue a CheckPluginStopEvent for a OBJLC object
+void
+nsObjectLoadingContent::QueueCheckPluginStopEvent()
+{
+  nsCOMPtr<nsIRunnable> event = new CheckPluginStopEvent(this);
+  mPendingCheckPluginStopEvent = event;
+
+  NS_DispatchToCurrentThread(event);
+}
+
+// Tedious syntax to create a plugin stream listener with checks and put it in
+// mFinalListener
+bool
+nsObjectLoadingContent::MakePluginListener()
+{
+  if (!mInstanceOwner) {
+    NS_NOTREACHED("expecting a spawned plugin");
+    return false;
+  }
+  RefPtr<nsPluginHost> pluginHost = nsPluginHost::GetInst();
+  if (!pluginHost) {
+    NS_NOTREACHED("No pluginHost");
+    return false;
+  }
+  NS_ASSERTION(!mFinalListener, "overwriting a final listener");
+  nsresult rv;
+  RefPtr<nsNPAPIPluginInstance> inst;
+  nsCOMPtr<nsIStreamListener> finalListener;
+  rv = mInstanceOwner->GetInstance(getter_AddRefs(inst));
+  NS_ENSURE_SUCCESS(rv, false);
+  rv = pluginHost->NewPluginStreamListener(mURI, inst,
+                                           getter_AddRefs(finalListener));
+  NS_ENSURE_SUCCESS(rv, false);
+  mFinalListener = finalListener;
+  return true;
+}
+
+
+bool
+nsObjectLoadingContent::IsSupportedDocument(const nsCString& aMimeType)
+{
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  NS_ASSERTION(thisContent, "must be a content");
+
+  nsCOMPtr<nsIWebNavigationInfo> info(
+    do_GetService(NS_WEBNAVIGATION_INFO_CONTRACTID));
+  if (!info) {
+    return false;
+  }
+
+  nsCOMPtr<nsIWebNavigation> webNav;
+  nsIDocument* currentDoc = thisContent->GetComposedDoc();
+  if (currentDoc) {
+    webNav = do_GetInterface(currentDoc->GetWindow());
+  }
+
+  uint32_t supported;
+  nsresult rv = info->IsTypeSupported(aMimeType, webNav, &supported);
+
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  if (supported != nsIWebNavigationInfo::UNSUPPORTED) {
+    // Don't want to support plugins as documents
+    return supported != nsIWebNavigationInfo::PLUGIN;
+  }
+
+  // Try a stream converter
+  // NOTE: We treat any type we can convert from as a supported type. If a
+  // type is not actually supported, the URI loader will detect that and
+  // return an error, and we'll fallback.
+  nsCOMPtr<nsIStreamConverterService> convServ =
+    do_GetService("@mozilla.org/streamConverters;1");
+  bool canConvert = false;
+  if (convServ) {
+    rv = convServ->CanConvert(aMimeType.get(), "*/*", &canConvert);
+  }
+  return NS_SUCCEEDED(rv) && canConvert;
+}
+
+nsresult
+nsObjectLoadingContent::BindToTree(nsIDocument* aDocument,
+                                   nsIContent* aParent,
+                                   nsIContent* aBindingParent,
+                                   bool aCompileEventHandlers)
+{
+  nsImageLoadingContent::BindToTree(aDocument, aParent, aBindingParent,
+                                    aCompileEventHandlers);
+
+  if (aDocument) {
+    return aDocument->AddPlugin(this);
+  }
+  return NS_OK;
+}
+
+void
+nsObjectLoadingContent::UnbindFromTree(bool aDeep, bool aNullParent)
+{
+  nsImageLoadingContent::UnbindFromTree(aDeep, aNullParent);
+
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIObjectLoadingContent*>(this));
+  MOZ_ASSERT(thisContent);
+  nsIDocument* ownerDoc = thisContent->OwnerDoc();
+  ownerDoc->RemovePlugin(this);
+
+  if (mType == eType_Plugin && (mInstanceOwner || mInstantiating)) {
+    // we'll let the plugin continue to run at least until we get back to
+    // the event loop. If we get back to the event loop and the node
+    // has still not been added back to the document then we tear down the
+    // plugin
+    QueueCheckPluginStopEvent();
+  } else if (mType != eType_Image) {
+    // nsImageLoadingContent handles the image case.
+    // Reset state and clear pending events
+    /// XXX(johns): The implementation for GenericFrame notes that ideally we
+    ///             would keep the docshell around, but trash the frameloader
+    UnloadObject();
+  }
+  nsIDocument* doc = thisContent->GetComposedDoc();
+  if (doc && doc->IsActive()) {
+    nsCOMPtr<nsIRunnable> ev = new nsSimplePluginEvent(doc,
+                                                       NS_LITERAL_STRING("PluginRemoved"));
+    NS_DispatchToCurrentThread(ev);
+  }
+}
+
+nsObjectLoadingContent::nsObjectLoadingContent()
+  : mType(eType_Loading)
+  , mFallbackType(eFallbackAlternate)
+  , mRunID(0)
+  , mHasRunID(false)
+  , mChannelLoaded(false)
+  , mInstantiating(false)
+  , mNetworkCreated(true)
+  , mActivated(false)
+  , mContentBlockingEnabled(false)
+  , mIsStopping(false)
+  , mIsLoading(false)
+  , mScriptRequested(false)
+  , mRewrittenYoutubeEmbed(false)
+  , mPreferFallback(false)
+  , mPreferFallbackKnown(false) {}
+
+nsObjectLoadingContent::~nsObjectLoadingContent()
+{
+  // Should have been unbound from the tree at this point, and
+  // CheckPluginStopEvent keeps us alive
+  if (mFrameLoader) {
+    NS_NOTREACHED("Should not be tearing down frame loaders at this point");
+    mFrameLoader->Destroy();
+  }
+  if (mInstanceOwner || mInstantiating) {
+    // This is especially bad as delayed stop will try to hold on to this
+    // object...
+    NS_NOTREACHED("Should not be tearing down a plugin at this point!");
+    StopPluginInstance();
+  }
+  DestroyImageLoadingContent();
+}
+
+nsresult
+nsObjectLoadingContent::InstantiatePluginInstance(bool aIsLoading)
+{
+  if (mInstanceOwner || mType != eType_Plugin || (mIsLoading != aIsLoading) ||
+      mInstantiating) {
+    // If we hit this assertion it's probably because LoadObject re-entered :(
+    //
+    // XXX(johns): This hackiness will go away in bug 767635
+    NS_ASSERTION(mIsLoading || !aIsLoading,
+                 "aIsLoading should only be true inside LoadObject");
+    return NS_OK;
+  }
+
+  mInstantiating = true;
+  AutoSetInstantiatingToFalse autoInstantiating(this);
+
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent *>(this));
+
+  nsCOMPtr<nsIDocument> doc = thisContent->GetComposedDoc();
+  if (!doc || !InActiveDocument(thisContent)) {
+    NS_ERROR("Shouldn't be calling "
+             "InstantiatePluginInstance without an active document");
+    return NS_ERROR_FAILURE;
+  }
+
+  // Instantiating an instance can result in script execution, which
+  // can destroy this DOM object. Don't allow that for the scope
+  // of this method.
+  nsCOMPtr<nsIObjectLoadingContent> kungFuDeathGrip = this;
+
+  // Flush layout so that the frame is created if possible and the plugin is
+  // initialized with the latest information.
+  doc->FlushPendingNotifications(Flush_Layout);
+  // Flushing layout may have re-entered and loaded something underneath us
+  NS_ENSURE_TRUE(mInstantiating, NS_OK);
+
+  if (!thisContent->GetPrimaryFrame()) {
+    LOG(("OBJLC [%p]: Not instantiating plugin with no frame", this));
+    return NS_OK;
+  }
+
+  nsresult rv = NS_ERROR_FAILURE;
+  RefPtr<nsPluginHost> pluginHost = nsPluginHost::GetInst();
+
+  if (!pluginHost) {
+    NS_NOTREACHED("No pluginhost");
+    return NS_ERROR_FAILURE;
+  }
+
+  // If you add early return(s), be sure to balance this call to
+  // appShell->SuspendNative() with additional call(s) to
+  // appShell->ReturnNative().
+  nsCOMPtr<nsIAppShell> appShell = do_GetService(kAppShellCID);
+  if (appShell) {
+    appShell->SuspendNative();
+  }
+
+  RefPtr<nsPluginInstanceOwner> newOwner;
+  rv = pluginHost->InstantiatePluginInstance(mContentType,
+                                             mURI.get(), this,
+                                             getter_AddRefs(newOwner));
+
+  // XXX(johns): We don't suspend native inside stopping plugins...
+  if (appShell) {
+    appShell->ResumeNative();
+  }
+
+  if (!mInstantiating || NS_FAILED(rv)) {
+    LOG(("OBJLC [%p]: Plugin instantiation failed or re-entered, "
+         "killing old instance", this));
+    // XXX(johns): This needs to be de-duplicated with DoStopPlugin, but we
+    //             don't want to touch the protochain or delayed stop.
+    //             (Bug 767635)
+    if (newOwner) {
+      RefPtr<nsNPAPIPluginInstance> inst;
+      newOwner->GetInstance(getter_AddRefs(inst));
+      newOwner->SetFrame(nullptr);
+      if (inst) {
+        pluginHost->StopPluginInstance(inst);
+      }
+      newOwner->Destroy();
+    }
+    return NS_OK;
+  }
+
+  mInstanceOwner = newOwner;
+
+  if (mInstanceOwner) {
+    RefPtr<nsNPAPIPluginInstance> inst;
+    rv = mInstanceOwner->GetInstance(getter_AddRefs(inst));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    rv = inst->GetRunID(&mRunID);
+    mHasRunID = NS_SUCCEEDED(rv);
+  }
+
+  // Ensure the frame did not change during instantiation re-entry (common).
+  // HasNewFrame would not have mInstanceOwner yet, so the new frame would be
+  // dangling. (Bug 854082)
+  nsIFrame* frame = thisContent->GetPrimaryFrame();
+  if (frame && mInstanceOwner) {
+    mInstanceOwner->SetFrame(static_cast<nsPluginFrame*>(frame));
+
+    // Bug 870216 - Adobe Reader renders with incorrect dimensions until it gets
+    // a second SetWindow call. This is otherwise redundant.
+    mInstanceOwner->CallSetWindow();
+  }
+
+  // Set up scripting interfaces.
+  NotifyContentObjectWrapper();
+
+  RefPtr<nsNPAPIPluginInstance> pluginInstance;
+  GetPluginInstance(getter_AddRefs(pluginInstance));
+  if (pluginInstance) {
+    nsCOMPtr<nsIPluginTag> pluginTag;
+    pluginHost->GetPluginTagForInstance(pluginInstance,
+                                        getter_AddRefs(pluginTag));
+
+    nsCOMPtr<nsIBlocklistService> blocklist =
+      do_GetService("@mozilla.org/extensions/blocklist;1");
+    if (blocklist) {
+      uint32_t blockState = nsIBlocklistService::STATE_NOT_BLOCKED;
+      blocklist->GetPluginBlocklistState(pluginTag, EmptyString(),
+                                         EmptyString(), &blockState);
+      if (blockState == nsIBlocklistService::STATE_OUTDATED) {
+        // Fire plugin outdated event if necessary
+        LOG(("OBJLC [%p]: Dispatching plugin outdated event for content %p\n",
+             this));
+        nsCOMPtr<nsIRunnable> ev = new nsSimplePluginEvent(thisContent,
+                                                     NS_LITERAL_STRING("PluginOutdated"));
+        nsresult rv = NS_DispatchToCurrentThread(ev);
+        if (NS_FAILED(rv)) {
+          NS_WARNING("failed to dispatch nsSimplePluginEvent");
+        }
+      }
+    }
+
+    // If we have a URI but didn't open a channel yet (eAllowPluginSkipChannel)
+    // or we did load with a channel but are re-instantiating, re-open the
+    // channel. OpenChannel() performs security checks, and this plugin has
+    // already passed content policy in LoadObject.
+    if ((mURI && !mChannelLoaded) || (mChannelLoaded && !aIsLoading)) {
+      NS_ASSERTION(!mChannel, "should not have an existing channel here");
+      // We intentionally ignore errors here, leaving it up to the plugin to
+      // deal with not having an initial stream.
+      OpenChannel();
+    }
+  }
+
+  nsCOMPtr<nsIRunnable> ev = \
+    new nsSimplePluginEvent(thisContent,
+                            doc,
+                            NS_LITERAL_STRING("PluginInstantiated"));
+  NS_DispatchToCurrentThread(ev);
+
+#ifdef XP_MACOSX
+  HTMLObjectElement::HandlePluginInstantiated(thisContent->AsElement());
+#endif
+
+  return NS_OK;
+}
+
+void
+nsObjectLoadingContent::GetPluginAttributes(nsTArray<MozPluginParameter>& aAttributes)
+{
+  aAttributes = mCachedAttributes;
+}
+
+void
+nsObjectLoadingContent::GetPluginParameters(nsTArray<MozPluginParameter>& aParameters)
+{
+  aParameters = mCachedParameters;
+}
+
+void
+nsObjectLoadingContent::GetNestedParams(nsTArray<MozPluginParameter>& aParams,
+                                        bool aIgnoreCodebase)
+{
+  nsCOMPtr<nsIDOMElement> domElement =
+    do_QueryInterface(static_cast<nsIObjectLoadingContent*>(this));
+
+  nsCOMPtr<nsIDOMHTMLCollection> allParams;
+  NS_NAMED_LITERAL_STRING(xhtml_ns, "http://www.w3.org/1999/xhtml");
+  domElement->GetElementsByTagNameNS(xhtml_ns,
+        NS_LITERAL_STRING("param"), getter_AddRefs(allParams));
+
+  if (!allParams)
+    return;
+
+  uint32_t numAllParams;
+  allParams->GetLength(&numAllParams);
+  for (uint32_t i = 0; i < numAllParams; i++) {
+    nsCOMPtr<nsIDOMNode> pNode;
+    allParams->Item(i, getter_AddRefs(pNode));
+    nsCOMPtr<nsIDOMElement> element = do_QueryInterface(pNode);
+
+    if (!element)
+      continue;
+
+    nsAutoString name;
+    element->GetAttribute(NS_LITERAL_STRING("name"), name);
+
+    if (name.IsEmpty())
+      continue;
+
+    nsCOMPtr<nsIDOMNode> parent;
+    nsCOMPtr<nsIDOMHTMLObjectElement> domObject;
+    nsCOMPtr<nsIDOMHTMLAppletElement> domApplet;
+    pNode->GetParentNode(getter_AddRefs(parent));
+    while (!(domObject || domApplet) && parent) {
+      domObject = do_QueryInterface(parent);
+      domApplet = do_QueryInterface(parent);
+      nsCOMPtr<nsIDOMNode> temp;
+      parent->GetParentNode(getter_AddRefs(temp));
+      parent = temp;
+    }
+
+    if (domApplet) {
+      parent = do_QueryInterface(domApplet);
+    } else if (domObject) {
+      parent = do_QueryInterface(domObject);
+    } else {
+      continue;
+    }
+
+    nsCOMPtr<nsIDOMNode> domNode = do_QueryInterface(domElement);
+    if (parent == domNode) {
+      MozPluginParameter param;
+      element->GetAttribute(NS_LITERAL_STRING("name"), param.mName);
+      element->GetAttribute(NS_LITERAL_STRING("value"), param.mValue);
+
+      param.mName.Trim(" \n\r\t\b", true, true, false);
+      param.mValue.Trim(" \n\r\t\b", true, true, false);
+
+      // ignore codebase param if it was already added in the attributes array.
+      if (aIgnoreCodebase && param.mName.EqualsIgnoreCase("codebase")) {
+        continue;
+      }
+
+      aParams.AppendElement(param);
+    }
+  }
+}
+
+nsresult
+nsObjectLoadingContent::BuildParametersArray()
+{
+  if (mCachedAttributes.Length() || mCachedParameters.Length()) {
+    MOZ_ASSERT(false, "Parameters array should be empty.");
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIContent> content =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+
+  for (uint32_t i = 0; i != content->GetAttrCount(); i += 1) {
+    MozPluginParameter param;
+    const nsAttrName* attrName = content->GetAttrNameAt(i);
+    nsIAtom* atom = attrName->LocalName();
+    content->GetAttr(attrName->NamespaceID(), atom, param.mValue);
+    atom->ToString(param.mName);
+    mCachedAttributes.AppendElement(param);
+  }
+
+  bool isJava = IsJavaMIME(mContentType);
+
+  nsCString codebase;
+  if (isJava) {
+      nsresult rv = mBaseURI->GetSpec(codebase);
+      NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  nsAdoptingCString wmodeOverride = Preferences::GetCString("plugins.force.wmode");
+  for (uint32_t i = 0; i < mCachedAttributes.Length(); i++) {
+    if (!wmodeOverride.IsEmpty() && mCachedAttributes[i].mName.EqualsIgnoreCase("wmode")) {
+      CopyASCIItoUTF16(wmodeOverride, mCachedAttributes[i].mValue);
+      wmodeOverride.Truncate();
+    } else if (!codebase.IsEmpty() && mCachedAttributes[i].mName.EqualsIgnoreCase("codebase")) {
+      CopyASCIItoUTF16(codebase, mCachedAttributes[i].mValue);
+      codebase.Truncate();
+    }
+  }
+
+  if (!wmodeOverride.IsEmpty()) {
+    MozPluginParameter param;
+    param.mName = NS_LITERAL_STRING("wmode");
+    CopyASCIItoUTF16(wmodeOverride, param.mValue);
+    mCachedAttributes.AppendElement(param);
+  }
+
+  if (!codebase.IsEmpty()) {
+    MozPluginParameter param;
+    param.mName = NS_LITERAL_STRING("codebase");
+    CopyASCIItoUTF16(codebase, param.mValue);
+    mCachedAttributes.AppendElement(param);
+  }
+
+  // Some plugins were never written to understand the "data" attribute of the OBJECT tag.
+  // Real and WMP will not play unless they find a "src" attribute, see bug 152334.
+  // Nav 4.x would simply replace the "data" with "src". Because some plugins correctly
+  // look for "data", lets instead copy the "data" attribute and add another entry
+  // to the bottom of the array if there isn't already a "src" specified.
+  if (content->IsHTMLElement(nsGkAtoms::object) &&
+      !content->HasAttr(kNameSpaceID_None, nsGkAtoms::src)) {
+    MozPluginParameter param;
+    content->GetAttr(kNameSpaceID_None, nsGkAtoms::data, param.mValue);
+    if (!param.mValue.IsEmpty()) {
+      param.mName = NS_LITERAL_STRING("SRC");
+      mCachedAttributes.AppendElement(param);
+    }
+  }
+
+  GetNestedParams(mCachedParameters, isJava);
+
+  return NS_OK;
+}
+
+void
+nsObjectLoadingContent::NotifyOwnerDocumentActivityChanged()
+{
+  // XXX(johns): We cannot touch plugins or run arbitrary script from this call,
+  //             as nsDocument is in a non-reentrant state.
+
+  // If we have a plugin we want to queue an event to stop it unless we are
+  // moved into an active document before returning to the event loop.
+  if (mInstanceOwner || mInstantiating) {
+    QueueCheckPluginStopEvent();
+  }
+}
+
+// nsIRequestObserver
+NS_IMETHODIMP
+nsObjectLoadingContent::OnStartRequest(nsIRequest *aRequest,
+                                       nsISupports *aContext)
+{
+  PROFILER_LABEL("nsObjectLoadingContent", "OnStartRequest",
+    js::ProfileEntry::Category::NETWORK);
+
+  LOG(("OBJLC [%p]: Channel OnStartRequest", this));
+
+  if (aRequest != mChannel || !aRequest) {
+    // happens when a new load starts before the previous one got here
+    return NS_BINDING_ABORTED;
+  }
+
+  // If we already switched to type plugin, this channel can just be passed to
+  // the final listener.
+  if (mType == eType_Plugin) {
+    if (!mInstanceOwner) {
+      // We drop mChannel when stopping plugins, so something is wrong
+      NS_NOTREACHED("Opened a channel in plugin mode, but don't have a plugin");
+      return NS_BINDING_ABORTED;
+    }
+    if (MakePluginListener()) {
+      return mFinalListener->OnStartRequest(aRequest, nullptr);
+    } else {
+      NS_NOTREACHED("Failed to create PluginStreamListener, aborting channel");
+      return NS_BINDING_ABORTED;
+    }
+  }
+
+  // Otherwise we should be state loading, and call LoadObject with the channel
+  if (mType != eType_Loading) {
+    NS_NOTREACHED("Should be type loading at this point");
+    return NS_BINDING_ABORTED;
+  }
+  NS_ASSERTION(!mChannelLoaded, "mChannelLoaded set already?");
+  NS_ASSERTION(!mFinalListener, "mFinalListener exists already?");
+
+  mChannelLoaded = true;
+
+  nsCOMPtr<nsIChannel> chan(do_QueryInterface(aRequest));
+  NS_ASSERTION(chan, "Why is our request not a channel?");
+
+  nsresult status = NS_OK;
+  bool success = IsSuccessfulRequest(aRequest, &status);
+
+  if (status == NS_ERROR_BLOCKED_URI) {
+    nsCOMPtr<nsIConsoleService> console(
+      do_GetService("@mozilla.org/consoleservice;1"));
+    if (console) {
+      nsCOMPtr<nsIURI> uri;
+      chan->GetURI(getter_AddRefs(uri));
+      nsString message = NS_LITERAL_STRING("Blocking ") +
+        NS_ConvertASCIItoUTF16(uri->GetSpecOrDefault().get()) +
+        NS_LITERAL_STRING(" since it was found on an internal Firefox blocklist.");
+      console->LogStringMessage(message.get());
+    }
+    Telemetry::Accumulate(Telemetry::PLUGIN_BLOCKED_FOR_STABILITY, 1);
+    mContentBlockingEnabled = true;
+    return NS_ERROR_FAILURE;
+  } else if (status == NS_ERROR_TRACKING_URI) {
+    mContentBlockingEnabled = true;
+    return NS_ERROR_FAILURE;
+  }
+
+  if (!success) {
+    LOG(("OBJLC [%p]: OnStartRequest: Request failed\n", this));
+    // If the request fails, we still call LoadObject() to handle fallback
+    // content and notifying of failure. (mChannelLoaded && !mChannel) indicates
+    // the bad state.
+    mChannel = nullptr;
+    LoadObject(true, false);
+    return NS_ERROR_FAILURE;
+  }
+
+  return LoadObject(true, false, aRequest);
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::OnStopRequest(nsIRequest *aRequest,
+                                      nsISupports *aContext,
+                                      nsresult aStatusCode)
+{
+  PROFILER_LABEL("nsObjectLoadingContent", "OnStopRequest",
+    js::ProfileEntry::Category::NETWORK);
+
+  // Handle object not loading error because source was a tracking URL.
+  // We make a note of this object node by including it in a dedicated
+  // array of blocked tracking nodes under its parent document.
+  if (aStatusCode == NS_ERROR_TRACKING_URI) {
+    nsCOMPtr<nsIContent> thisNode =
+      do_QueryInterface(static_cast<nsIObjectLoadingContent*>(this));
+    if (thisNode && thisNode->IsInComposedDoc()) {
+      thisNode->GetComposedDoc()->AddBlockedTrackingNode(thisNode);
+    }
+  }
+
+  NS_ENSURE_TRUE(nsContentUtils::LegacyIsCallerChromeOrNativeCode(), NS_ERROR_NOT_AVAILABLE);
+
+  if (aRequest != mChannel) {
+    return NS_BINDING_ABORTED;
+  }
+
+  mChannel = nullptr;
+
+  if (mFinalListener) {
+    // This may re-enter in the case of plugin listeners
+    nsCOMPtr<nsIStreamListener> listenerGrip(mFinalListener);
+    mFinalListener = nullptr;
+    listenerGrip->OnStopRequest(aRequest, aContext, aStatusCode);
+  }
+
+  // Return value doesn't matter
+  return NS_OK;
+}
+
+
+// nsIStreamListener
+NS_IMETHODIMP
+nsObjectLoadingContent::OnDataAvailable(nsIRequest *aRequest,
+                                        nsISupports *aContext,
+                                        nsIInputStream *aInputStream,
+                                        uint64_t aOffset, uint32_t aCount)
+{
+  NS_ENSURE_TRUE(nsContentUtils::LegacyIsCallerChromeOrNativeCode(), NS_ERROR_NOT_AVAILABLE);
+
+  if (aRequest != mChannel) {
+    return NS_BINDING_ABORTED;
+  }
+
+  if (mFinalListener) {
+    // This may re-enter in the case of plugin listeners
+    nsCOMPtr<nsIStreamListener> listenerGrip(mFinalListener);
+    return listenerGrip->OnDataAvailable(aRequest, aContext, aInputStream,
+                                         aOffset, aCount);
+  }
+
+  // We shouldn't have a connected channel with no final listener
+  NS_NOTREACHED("Got data for channel with no connected final listener");
+  mChannel = nullptr;
+
+  return NS_ERROR_UNEXPECTED;
+}
+
+// nsIFrameLoaderOwner
+NS_IMETHODIMP
+nsObjectLoadingContent::GetFrameLoaderXPCOM(nsIFrameLoader** aFrameLoader)
+{
+  NS_IF_ADDREF(*aFrameLoader = mFrameLoader);
+  return NS_OK;
+}
+
+NS_IMETHODIMP_(already_AddRefed<nsFrameLoader>)
+nsObjectLoadingContent::GetFrameLoader()
+{
+  RefPtr<nsFrameLoader> loader = mFrameLoader;
+  return loader.forget();
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetParentApplication(mozIApplication** aApplication)
+{
+  if (!aApplication) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *aApplication = nullptr;
+  return NS_OK;
+}
+
+void
+nsObjectLoadingContent::PresetOpenerWindow(mozIDOMWindowProxy* aWindow, mozilla::ErrorResult& aRv)
+{
+  aRv.Throw(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::SetIsPrerendered()
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+void
+nsObjectLoadingContent::InternalSetFrameLoader(nsIFrameLoader* aNewFrameLoader)
+{
+  MOZ_CRASH("You shouldn't be calling this function, it doesn't make any sense on this type.");
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetActualType(nsACString& aType)
+{
+  aType = mContentType;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetDisplayedType(uint32_t* aType)
+{
+  *aType = DisplayedType();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::HasNewFrame(nsIObjectFrame* aFrame)
+{
+  if (mType != eType_Plugin) {
+    return NS_OK;
+  }
+
+  if (!aFrame) {
+    // Lost our frame. If we aren't going to be getting a new frame, e.g. we've
+    // become display:none, we'll want to stop the plugin. Queue a
+    // CheckPluginStopEvent
+    if (mInstanceOwner || mInstantiating) {
+      if (mInstanceOwner) {
+        mInstanceOwner->SetFrame(nullptr);
+      }
+      QueueCheckPluginStopEvent();
+    }
+    return NS_OK;
+  }
+
+  // Have a new frame
+
+  if (!mInstanceOwner) {
+    // We are successfully setup as type plugin, but have not spawned an
+    // instance due to a lack of a frame.
+    AsyncStartPluginInstance();
+    return NS_OK;
+  }
+
+  // Otherwise, we're just changing frames
+  // Set up relationship between instance owner and frame.
+  nsPluginFrame *objFrame = static_cast<nsPluginFrame*>(aFrame);
+  mInstanceOwner->SetFrame(objFrame);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetPluginInstance(nsNPAPIPluginInstance** aInstance)
+{
+  *aInstance = nullptr;
+
+  if (!mInstanceOwner) {
+    return NS_OK;
+  }
+
+  return mInstanceOwner->GetInstance(aInstance);
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetContentTypeForMIMEType(const nsACString& aMIMEType,
+                                                  uint32_t* aType)
+{
+  *aType = GetTypeOfContent(PromiseFlatCString(aMIMEType));
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetBaseURI(nsIURI **aResult)
+{
+  NS_IF_ADDREF(*aResult = mBaseURI);
+  return NS_OK;
+}
+
+// nsIInterfaceRequestor
+// We use a shim class to implement this so that JS consumers still
+// see an interface requestor even though WebIDL bindings don't expose
+// that stuff.
+class ObjectInterfaceRequestorShim final : public nsIInterfaceRequestor,
+                                           public nsIChannelEventSink,
+                                           public nsIStreamListener
+{
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(ObjectInterfaceRequestorShim,
+                                           nsIInterfaceRequestor)
+  NS_DECL_NSIINTERFACEREQUESTOR
+  // RefPtr<nsObjectLoadingContent> fails due to ambiguous AddRef/Release,
+  // hence the ugly static cast :(
+  NS_FORWARD_NSICHANNELEVENTSINK(static_cast<nsObjectLoadingContent *>
+                                 (mContent.get())->)
+  NS_FORWARD_NSISTREAMLISTENER  (static_cast<nsObjectLoadingContent *>
+                                 (mContent.get())->)
+  NS_FORWARD_NSIREQUESTOBSERVER (static_cast<nsObjectLoadingContent *>
+                                 (mContent.get())->)
+
+  explicit ObjectInterfaceRequestorShim(nsIObjectLoadingContent* aContent)
+    : mContent(aContent)
+  {}
+
+protected:
+  ~ObjectInterfaceRequestorShim() {}
+  nsCOMPtr<nsIObjectLoadingContent> mContent;
+};
+
+NS_IMPL_CYCLE_COLLECTION(ObjectInterfaceRequestorShim, mContent)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ObjectInterfaceRequestorShim)
+  NS_INTERFACE_MAP_ENTRY(nsIInterfaceRequestor)
+  NS_INTERFACE_MAP_ENTRY(nsIChannelEventSink)
+  NS_INTERFACE_MAP_ENTRY(nsIStreamListener)
+  NS_INTERFACE_MAP_ENTRY(nsIRequestObserver)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIInterfaceRequestor)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(ObjectInterfaceRequestorShim)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(ObjectInterfaceRequestorShim)
+
+NS_IMETHODIMP
+ObjectInterfaceRequestorShim::GetInterface(const nsIID & aIID, void **aResult)
+{
+  if (aIID.Equals(NS_GET_IID(nsIChannelEventSink))) {
+    nsIChannelEventSink* sink = this;
+    *aResult = sink;
+    NS_ADDREF(sink);
+    return NS_OK;
+  }
+  return NS_NOINTERFACE;
+}
+
+// nsIChannelEventSink
+NS_IMETHODIMP
+nsObjectLoadingContent::AsyncOnChannelRedirect(nsIChannel *aOldChannel,
+                                               nsIChannel *aNewChannel,
+                                               uint32_t aFlags,
+                                               nsIAsyncVerifyRedirectCallback *cb)
+{
+  // If we're already busy with a new load, or have no load at all,
+  // cancel the redirect.
+  if (!mChannel || aOldChannel != mChannel) {
+    return NS_BINDING_ABORTED;
+  }
+
+  mChannel = aNewChannel;
+  cb->OnRedirectVerifyCallback(NS_OK);
+  return NS_OK;
+}
+
+// <public>
+EventStates
+nsObjectLoadingContent::ObjectState() const
+{
+  switch (mType) {
+    case eType_Loading:
+      return NS_EVENT_STATE_LOADING;
+    case eType_Image:
+      return ImageState();
+    case eType_Plugin:
+    case eType_Document:
+      // These are OK. If documents start to load successfully, they display
+      // something, and are thus not broken in this sense. The same goes for
+      // plugins.
+      return EventStates();
+    case eType_Null:
+      switch (mFallbackType) {
+        case eFallbackSuppressed:
+          return NS_EVENT_STATE_SUPPRESSED;
+        case eFallbackUserDisabled:
+          return NS_EVENT_STATE_USERDISABLED;
+        case eFallbackClickToPlay:
+          return NS_EVENT_STATE_TYPE_CLICK_TO_PLAY;
+        case eFallbackDisabled:
+          return NS_EVENT_STATE_BROKEN | NS_EVENT_STATE_HANDLER_DISABLED;
+        case eFallbackBlocklisted:
+          return NS_EVENT_STATE_BROKEN | NS_EVENT_STATE_HANDLER_BLOCKED;
+        case eFallbackCrashed:
+          return NS_EVENT_STATE_BROKEN | NS_EVENT_STATE_HANDLER_CRASHED;
+        case eFallbackUnsupported:
+        case eFallbackOutdated:
+        case eFallbackAlternate:
+          return NS_EVENT_STATE_BROKEN;
+        case eFallbackVulnerableUpdatable:
+          return NS_EVENT_STATE_VULNERABLE_UPDATABLE;
+        case eFallbackVulnerableNoUpdate:
+          return NS_EVENT_STATE_VULNERABLE_NO_UPDATE;
+      }
+  }
+  NS_NOTREACHED("unknown type?");
+  return NS_EVENT_STATE_LOADING;
+}
+
+// Returns false if mBaseURI is not acceptable for java applets.
+bool
+nsObjectLoadingContent::CheckJavaCodebase()
+{
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  nsCOMPtr<nsIScriptSecurityManager> secMan =
+    nsContentUtils::GetSecurityManager();
+  nsCOMPtr<nsINetUtil> netutil = do_GetNetUtil();
+  NS_ASSERTION(thisContent && secMan && netutil, "expected interfaces");
+
+
+  // Note that mBaseURI is this tag's requested base URI, not the codebase of
+  // the document for security purposes
+  nsresult rv = secMan->CheckLoadURIWithPrincipal(thisContent->NodePrincipal(),
+                                                  mBaseURI, 0);
+  if (NS_FAILED(rv)) {
+    LOG(("OBJLC [%p]: Java codebase check failed", this));
+    return false;
+  }
+
+  nsCOMPtr<nsIURI> principalBaseURI;
+  rv = thisContent->NodePrincipal()->GetURI(getter_AddRefs(principalBaseURI));
+  if (NS_FAILED(rv)) {
+    NS_NOTREACHED("Failed to URI from node principal?");
+    return false;
+  }
+  // We currently allow java's codebase to be non-same-origin, with
+  // the exception of URIs that represent local files
+  if (NS_URIIsLocalFile(mBaseURI) &&
+      nsScriptSecurityManager::GetStrictFileOriginPolicy() &&
+      !NS_RelaxStrictFileOriginPolicy(mBaseURI, principalBaseURI, true)) {
+    LOG(("OBJLC [%p]: Java failed RelaxStrictFileOriginPolicy for file URI",
+         this));
+    return false;
+  }
+
+  return true;
+}
+
+void
+nsObjectLoadingContent::MaybeRewriteYoutubeEmbed(nsIURI* aURI, nsIURI* aBaseURI, nsIURI** aOutURI)
+{
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  NS_ASSERTION(thisContent, "Must be an instance of content");
+
+  // We're only interested in switching out embed and object tags
+  if (!thisContent->NodeInfo()->Equals(nsGkAtoms::embed) &&
+      !thisContent->NodeInfo()->Equals(nsGkAtoms::object)) {
+    return;
+  }
+
+  nsCOMPtr<nsIEffectiveTLDService> tldService =
+    do_GetService(NS_EFFECTIVETLDSERVICE_CONTRACTID);
+  // If we can't analyze the URL, just pass on through.
+  if(!tldService) {
+    NS_WARNING("Could not get TLD service!");
+    return;
+  }
+
+  nsAutoCString currentBaseDomain;
+  bool ok = NS_SUCCEEDED(tldService->GetBaseDomain(aURI, 0, currentBaseDomain));
+  if (!ok) {
+    // Data URIs (commonly used for things like svg embeds) won't parse
+    // correctly, so just fail silently here.
+    return;
+  }
+
+  // See if URL is referencing youtube
+  if (!currentBaseDomain.EqualsLiteral("youtube.com")) {
+    return;
+  }
+
+  // We should only rewrite URLs with paths starting with "/v/", as we shouldn't
+  // touch object nodes with "/embed/" urls that already do that right thing.
+  nsAutoCString path;
+  aURI->GetPath(path);
+  if (!StringBeginsWith(path, NS_LITERAL_CSTRING("/v/"))) {
+    return;
+  }
+
+  // See if requester is planning on using the JS API.
+  nsAutoCString uri;
+  nsresult rv = aURI->GetSpec(uri);
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  if (uri.Find("enablejsapi=1", true, 0, -1) != kNotFound) {
+    Telemetry::Accumulate(Telemetry::YOUTUBE_NONREWRITABLE_EMBED_SEEN, 1);
+    return;
+  }
+
+  // Some YouTube urls have parameters in path components, e.g.
+  // http://youtube.com/embed/7LcUOEP7Brc&start=35. These URLs work with flash,
+  // but break iframe/object embedding. If this situation occurs with rewritten
+  // URLs, convert the parameters to query in order to make the video load
+  // correctly as an iframe. In either case, warn about it in the
+  // developer console.
+  int32_t ampIndex = uri.FindChar('&', 0);
+  bool replaceQuery = false;
+  if (ampIndex != -1) {
+    int32_t qmIndex = uri.FindChar('?', 0);
+    if (qmIndex == -1 ||
+        qmIndex > ampIndex) {
+      replaceQuery = true;
+    }
+  }
+
+  // If we've made it this far, we've got a rewritable embed. Log it in
+  // telemetry.
+  Telemetry::Accumulate(Telemetry::YOUTUBE_REWRITABLE_EMBED_SEEN, 1);
+
+  // If we're pref'd off, return after telemetry has been logged.
+  if (!Preferences::GetBool(kPrefYoutubeRewrite)) {
+    return;
+  }
+
+  nsAutoString utf16OldURI = NS_ConvertUTF8toUTF16(uri);
+  // If we need to convert the URL, it means an ampersand comes first.
+  // Use the index we found earlier.
+  if (replaceQuery) {
+    // Replace question marks with ampersands.
+    uri.ReplaceChar('?', '&');
+    // Replace the first ampersand with a question mark.
+    uri.SetCharAt('?', ampIndex);
+  }
+  // Switch out video access url formats, which should possibly allow HTML5
+  // video loading.
+  uri.ReplaceSubstring(NS_LITERAL_CSTRING("/v/"),
+                       NS_LITERAL_CSTRING("/embed/"));
+  nsAutoString utf16URI = NS_ConvertUTF8toUTF16(uri);
+  rv = nsContentUtils::NewURIWithDocumentCharset(aOutURI,
+                                                 utf16URI,
+                                                 thisContent->OwnerDoc(),
+                                                 aBaseURI);
+  if (NS_FAILED(rv)) {
+    return;
+  }
+  const char16_t* params[] = { utf16OldURI.get(), utf16URI.get() };
+  const char* msgName;
+  // If there's no query to rewrite, just notify in the developer console
+  // that we're changing the embed.
+  if (!replaceQuery) {
+    msgName = "RewriteYouTubeEmbed";
+  } else {
+    msgName = "RewriteYouTubeEmbedPathParams";
+  }
+  nsContentUtils::ReportToConsole(nsIScriptError::warningFlag,
+                                  NS_LITERAL_CSTRING("Plugins"),
+                                  thisContent->OwnerDoc(),
+                                  nsContentUtils::eDOM_PROPERTIES,
+                                  msgName,
+                                  params, ArrayLength(params));
+}
+
+bool
+nsObjectLoadingContent::CheckLoadPolicy(int16_t *aContentPolicy)
+{
+  if (!aContentPolicy || !mURI) {
+    NS_NOTREACHED("Doing it wrong");
+    return false;
+  }
+
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  NS_ASSERTION(thisContent, "Must be an instance of content");
+
+  nsIDocument* doc = thisContent->OwnerDoc();
+
+  nsContentPolicyType contentPolicyType = GetContentPolicyType();
+
+  *aContentPolicy = nsIContentPolicy::ACCEPT;
+  nsresult rv = NS_CheckContentLoadPolicy(contentPolicyType,
+                                          mURI,
+                                          doc->NodePrincipal(),
+                                          thisContent,
+                                          mContentType,
+                                          nullptr, //extra
+                                          aContentPolicy,
+                                          nsContentUtils::GetContentPolicy(),
+                                          nsContentUtils::GetSecurityManager());
+  NS_ENSURE_SUCCESS(rv, false);
+  if (NS_CP_REJECTED(*aContentPolicy)) {
+    LOG(("OBJLC [%p]: Content policy denied load of %s",
+         this, mURI->GetSpecOrDefault().get()));
+    return false;
+  }
+
+  return true;
+}
+
+bool
+nsObjectLoadingContent::CheckProcessPolicy(int16_t *aContentPolicy)
+{
+  if (!aContentPolicy) {
+    NS_NOTREACHED("Null out variable");
+    return false;
+  }
+
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  NS_ASSERTION(thisContent, "Must be an instance of content");
+
+  nsIDocument* doc = thisContent->OwnerDoc();
+
+  int32_t objectType;
+  switch (mType) {
+    case eType_Image:
+      objectType = nsIContentPolicy::TYPE_INTERNAL_IMAGE;
+      break;
+    case eType_Document:
+      objectType = nsIContentPolicy::TYPE_DOCUMENT;
+      break;
+    case eType_Plugin:
+      objectType = GetContentPolicyType();
+      break;
+    default:
+      NS_NOTREACHED("Calling checkProcessPolicy with a unloadable type");
+      return false;
+  }
+
+  *aContentPolicy = nsIContentPolicy::ACCEPT;
+  nsresult rv =
+    NS_CheckContentProcessPolicy(objectType,
+                                 mURI ? mURI : mBaseURI,
+                                 doc->NodePrincipal(),
+                                 static_cast<nsIImageLoadingContent*>(this),
+                                 mContentType,
+                                 nullptr, //extra
+                                 aContentPolicy,
+                                 nsContentUtils::GetContentPolicy(),
+                                 nsContentUtils::GetSecurityManager());
+  NS_ENSURE_SUCCESS(rv, false);
+
+  if (NS_CP_REJECTED(*aContentPolicy)) {
+    LOG(("OBJLC [%p]: CheckContentProcessPolicy rejected load", this));
+    return false;
+  }
+
+  return true;
+}
+
+nsObjectLoadingContent::ParameterUpdateFlags
+nsObjectLoadingContent::UpdateObjectParameters(bool aJavaURI)
+{
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  NS_ASSERTION(thisContent, "Must be an instance of content");
+
+  uint32_t caps = GetCapabilities();
+  LOG(("OBJLC [%p]: Updating object parameters", this));
+
+  nsresult rv;
+  nsAutoCString newMime;
+  nsAutoString typeAttr;
+  nsCOMPtr<nsIURI> newURI;
+  nsCOMPtr<nsIURI> newBaseURI;
+  ObjectType newType;
+  bool isJava = false;
+  // Set if this state can't be used to load anything, forces eType_Null
+  bool stateInvalid = false;
+  // Indicates what parameters changed.
+  // eParamChannelChanged - means parameters that affect channel opening
+  //                        decisions changed
+  // eParamStateChanged -   means anything that affects what content we load
+  //                        changed, even if the channel we'd open remains the
+  //                        same.
+  //
+  // State changes outside of the channel parameters only matter if we've
+  // already opened a channel or tried to instantiate content, whereas channel
+  // parameter changes require re-opening the channel even if we haven't gotten
+  // that far.
+  nsObjectLoadingContent::ParameterUpdateFlags retval = eParamNoChange;
+
+  ///
+  /// Initial MIME Type
+  ///
+
+  if (aJavaURI || thisContent->NodeInfo()->Equals(nsGkAtoms::applet)) {
+    nsAdoptingCString javaMIME = Preferences::GetCString(kPrefJavaMIME);
+    newMime = javaMIME;
+    NS_ASSERTION(IsJavaMIME(newMime),
+                 "plugin.mime.java should be recognized as java");
+    isJava = true;
+  } else {
+    nsAutoString rawTypeAttr;
+    thisContent->GetAttr(kNameSpaceID_None, nsGkAtoms::type, rawTypeAttr);
+    if (!rawTypeAttr.IsEmpty()) {
+      typeAttr = rawTypeAttr;
+      CopyUTF16toUTF8(rawTypeAttr, newMime);
+      isJava = IsJavaMIME(newMime);
+    }
+  }
+
+  ///
+  /// classID
+  ///
+
+  if (caps & eSupportClassID) {
+    nsAutoString classIDAttr;
+    thisContent->GetAttr(kNameSpaceID_None, nsGkAtoms::classid, classIDAttr);
+    if (!classIDAttr.IsEmpty()) {
+      // Our classid support is limited to 'java:' ids
+      nsAdoptingCString javaMIME = Preferences::GetCString(kPrefJavaMIME);
+      NS_ASSERTION(IsJavaMIME(javaMIME),
+                   "plugin.mime.java should be recognized as java");
+      RefPtr<nsPluginHost> pluginHost = nsPluginHost::GetInst();
+      if (StringBeginsWith(classIDAttr, NS_LITERAL_STRING("java:")) &&
+          pluginHost &&
+          pluginHost->HavePluginForType(javaMIME)) {
+        newMime = javaMIME;
+        isJava = true;
+      } else {
+        // XXX(johns): Our de-facto behavior since forever was to refuse to load
+        // Objects who don't have a classid we support, regardless of other type
+        // or uri info leads to a valid plugin.
+        newMime.Truncate();
+        stateInvalid = true;
+      }
+    }
+  }
+
+  ///
+  /// Codebase
+  ///
+
+  nsAutoString codebaseStr;
+  nsCOMPtr<nsIURI> docBaseURI = thisContent->GetBaseURI();
+  bool hasCodebase = thisContent->HasAttr(kNameSpaceID_None, nsGkAtoms::codebase);
+  if (hasCodebase)
+    thisContent->GetAttr(kNameSpaceID_None, nsGkAtoms::codebase, codebaseStr);
+
+
+  // Java wants the codebase attribute even if it occurs in <param> tags
+  if (isJava) {
+    // Find all <param> tags that are nested beneath us, but not beneath another
+    // object/applet tag.
+    nsTArray<MozPluginParameter> params;
+    GetNestedParams(params, false);
+    for (uint32_t i = 0; i < params.Length(); i++) {
+      if (params[i].mName.EqualsIgnoreCase("codebase")) {
+        hasCodebase = true;
+        codebaseStr = params[i].mValue;
+      }
+    }
+  }
+
+  if (isJava && hasCodebase && codebaseStr.IsEmpty()) {
+    // Java treats codebase="" as "/"
+    codebaseStr.Assign('/');
+    // XXX(johns): This doesn't cover the case of "https:" which java would
+    //             interpret as "https:///" but we interpret as this document's
+    //             URI but with a changed scheme.
+  } else if (isJava && !hasCodebase) {
+    // Java expects a directory as the codebase, or else it will construct
+    // relative URIs incorrectly :(
+    codebaseStr.Assign('.');
+  }
+
+  if (!codebaseStr.IsEmpty()) {
+    rv = nsContentUtils::NewURIWithDocumentCharset(getter_AddRefs(newBaseURI),
+                                                   codebaseStr,
+                                                   thisContent->OwnerDoc(),
+                                                   docBaseURI);
+    if (NS_SUCCEEDED(rv)) {
+      NS_TryToSetImmutable(newBaseURI);
+    } else {
+      // Malformed URI
+      LOG(("OBJLC [%p]: Could not parse plugin's codebase as a URI, "
+           "will use document baseURI instead", this));
+    }
+  }
+
+  // If we failed to build a valid URI, use the document's base URI
+  if (!newBaseURI) {
+    newBaseURI = docBaseURI;
+  }
+
+  ///
+  /// URI
+  ///
+
+  nsAutoString uriStr;
+  // Different elements keep this in various locations
+  if (isJava) {
+    // Applet tags and embed/object with explicit java MIMEs have src/data
+    // attributes that are not meant to be parsed as URIs or opened by the
+    // browser -- act as if they are null. (Setting these attributes triggers a
+    // force-load, so tracking the old value to determine if they have changed
+    // is not necessary.)
+  } else if (thisContent->NodeInfo()->Equals(nsGkAtoms::object)) {
+    thisContent->GetAttr(kNameSpaceID_None, nsGkAtoms::data, uriStr);
+  } else if (thisContent->NodeInfo()->Equals(nsGkAtoms::embed)) {
+    thisContent->GetAttr(kNameSpaceID_None, nsGkAtoms::src, uriStr);
+  } else {
+    // Applet tags should always have a java MIME type at this point
+    NS_NOTREACHED("Unrecognized plugin-loading tag");
+  }
+
+  mRewrittenYoutubeEmbed = false;
+  // Note that the baseURI changing could affect the newURI, even if uriStr did
+  // not change.
+  if (!uriStr.IsEmpty()) {
+    rv = nsContentUtils::NewURIWithDocumentCharset(getter_AddRefs(newURI),
+                                                   uriStr,
+                                                   thisContent->OwnerDoc(),
+                                                   newBaseURI);
+    nsCOMPtr<nsIURI> rewrittenURI;
+    MaybeRewriteYoutubeEmbed(newURI,
+                             newBaseURI,
+                             getter_AddRefs(rewrittenURI));
+    if (rewrittenURI) {
+      newURI = rewrittenURI;
+      mRewrittenYoutubeEmbed = true;
+      newMime = NS_LITERAL_CSTRING("text/html");
+    }
+
+    if (NS_SUCCEEDED(rv)) {
+      NS_TryToSetImmutable(newURI);
+    } else {
+      stateInvalid = true;
+    }
+  }
+
+  // For eAllowPluginSkipChannel tags, if we have a non-plugin type, but can get
+  // a plugin type from the extension, prefer that to falling back to a channel.
+  if (GetTypeOfContent(newMime) != eType_Plugin && newURI &&
+      (caps & eAllowPluginSkipChannel) &&
+      IsPluginEnabledByExtension(newURI, newMime)) {
+    LOG(("OBJLC [%p]: Using extension as type hint (%s)", this, newMime.get()));
+    if (!isJava && IsJavaMIME(newMime)) {
+      return UpdateObjectParameters(true);
+    }
+  }
+
+  ///
+  /// Check if the original (pre-channel) content-type or URI changed, and
+  /// record mOriginal{ContentType,URI}
+  ///
+
+  if ((mOriginalContentType != newMime) || !URIEquals(mOriginalURI, newURI)) {
+    // These parameters changing requires re-opening the channel, so don't
+    // consider the currently-open channel below
+    // XXX(johns): Changing the mime type might change our decision on whether
+    //             or not we load a channel, so we count changes to it as a
+    //             channel parameter change for the sake of simplicity.
+    retval = (ParameterUpdateFlags)(retval | eParamChannelChanged);
+    LOG(("OBJLC [%p]: Channel parameters changed", this));
+  }
+  mOriginalContentType = newMime;
+  mOriginalURI = newURI;
+
+  ///
+  /// If we have a channel, see if its MIME type should take precendence and
+  /// check the final (redirected) URL
+  ///
+
+  // If we have a loaded channel and channel parameters did not change, use it
+  // to determine what we would load.
+  bool useChannel = mChannelLoaded && !(retval & eParamChannelChanged);
+  // If we have a channel and are type loading, as opposed to having an existing
+  // channel for a previous load.
+  bool newChannel = useChannel && mType == eType_Loading;
+
+  if (newChannel && mChannel) {
+    nsCString channelType;
+    rv = mChannel->GetContentType(channelType);
+    if (NS_FAILED(rv)) {
+      NS_NOTREACHED("GetContentType failed");
+      stateInvalid = true;
+      channelType.Truncate();
+    }
+
+    LOG(("OBJLC [%p]: Channel has a content type of %s", this, channelType.get()));
+
+    bool binaryChannelType = false;
+    if (channelType.EqualsASCII(APPLICATION_GUESS_FROM_EXT)) {
+      channelType = APPLICATION_OCTET_STREAM;
+      mChannel->SetContentType(channelType);
+      binaryChannelType = true;
+    } else if (channelType.EqualsASCII(APPLICATION_OCTET_STREAM)
+               || channelType.EqualsASCII(BINARY_OCTET_STREAM)) {
+      binaryChannelType = true;
+    }
+
+    // Channel can change our URI through redirection
+    rv = NS_GetFinalChannelURI(mChannel, getter_AddRefs(newURI));
+    if (NS_FAILED(rv)) {
+      NS_NOTREACHED("NS_GetFinalChannelURI failure");
+      stateInvalid = true;
+    }
+
+    ObjectType typeHint = newMime.IsEmpty() ?
+                          eType_Null : GetTypeOfContent(newMime);
+
+    //
+    // In order of preference:
+    //
+    // 1) Perform typemustmatch check.
+    //    If check is sucessful use type without further checks.
+    //    If check is unsuccessful set stateInvalid to true
+    // 2) Use our type hint if it matches a plugin
+    // 3) If we have eAllowPluginSkipChannel, use the uri file extension if
+    //    it matches a plugin
+    // 4) If the channel returns a binary stream type:
+    //    4a) If we have a type non-null non-document type hint, use that
+    //    4b) If the uri file extension matches a plugin type, use that
+    // 5) Use the channel type
+
+    bool overrideChannelType = false;
+    if (thisContent->HasAttr(kNameSpaceID_None, nsGkAtoms::typemustmatch)) {
+      if (!typeAttr.LowerCaseEqualsASCII(channelType.get())) {
+        stateInvalid = true;
+      }
+    } else if (typeHint == eType_Plugin) {
+      LOG(("OBJLC [%p]: Using plugin type hint in favor of any channel type",
+           this));
+      overrideChannelType = true;
+    } else if ((caps & eAllowPluginSkipChannel) &&
+               IsPluginEnabledByExtension(newURI, newMime)) {
+      LOG(("OBJLC [%p]: Using extension as type hint for "
+           "eAllowPluginSkipChannel tag (%s)", this, newMime.get()));
+      overrideChannelType = true;
+    } else if (binaryChannelType &&
+               typeHint != eType_Null && typeHint != eType_Document) {
+      LOG(("OBJLC [%p]: Using type hint in favor of binary channel type",
+           this));
+      overrideChannelType = true;
+    } else if (binaryChannelType &&
+               IsPluginEnabledByExtension(newURI, newMime)) {
+      LOG(("OBJLC [%p]: Using extension as type hint for binary channel (%s)",
+           this, newMime.get()));
+      overrideChannelType = true;
+    }
+
+    if (overrideChannelType) {
+      // Set the type we'll use for dispatch on the channel.  Otherwise we could
+      // end up trying to dispatch to a nsFrameLoader, which will complain that
+      // it couldn't find a way to handle application/octet-stream
+      nsAutoCString parsedMime, dummy;
+      NS_ParseResponseContentType(newMime, parsedMime, dummy);
+      if (!parsedMime.IsEmpty()) {
+        mChannel->SetContentType(parsedMime);
+      }
+    } else {
+      newMime = channelType;
+      if (IsJavaMIME(newMime)) {
+        // Java does not load with a channel, and being java retroactively
+        // changes how we may have interpreted the codebase to construct this
+        // URI above.  Because the behavior here is more or less undefined, play
+        // it safe and reject the load.
+        LOG(("OBJLC [%p]: Refusing to load with channel with java MIME",
+             this));
+        stateInvalid = true;
+      }
+    }
+  } else if (newChannel) {
+    LOG(("OBJLC [%p]: We failed to open a channel, marking invalid", this));
+    stateInvalid = true;
+  }
+
+  ///
+  /// Determine final type
+  ///
+  // In order of preference:
+  //  1) If we have attempted channel load, or set stateInvalid above, the type
+  //     is always null (fallback)
+  //  2) If we have a loaded channel, we grabbed its mimeType above, use that
+  //     type.
+  //  3) If we have a plugin type and no URI, use that type.
+  //  4) If we have a plugin type and eAllowPluginSkipChannel, use that type.
+  //  5) if we have a URI, set type to loading to indicate we'd need a channel
+  //     to proceed.
+  //  6) Otherwise, type null to indicate unloadable content (fallback)
+  //
+
+  if (stateInvalid) {
+    newType = eType_Null;
+    newMime.Truncate();
+  } else if (newChannel) {
+    // If newChannel is set above, we considered it in setting newMime
+    newType = GetTypeOfContent(newMime);
+    LOG(("OBJLC [%p]: Using channel type", this));
+  } else if (((caps & eAllowPluginSkipChannel) || !newURI) &&
+             GetTypeOfContent(newMime) == eType_Plugin) {
+    newType = eType_Plugin;
+    LOG(("OBJLC [%p]: Plugin type with no URI, skipping channel load", this));
+  } else if (newURI) {
+    // We could potentially load this if we opened a channel on mURI, indicate
+    // This by leaving type as loading
+    newType = eType_Loading;
+  } else {
+    // Unloadable - no URI, and no plugin type. Non-plugin types (images,
+    // documents) always load with a channel.
+    newType = eType_Null;
+  }
+
+  ///
+  /// Handle existing channels
+  ///
+
+  if (useChannel && newType == eType_Loading) {
+    // We decided to use a channel, and also that the previous channel is still
+    // usable, so re-use the existing values.
+    newType = mType;
+    newMime = mContentType;
+    newURI = mURI;
+  } else if (useChannel && !newChannel) {
+    // We have an existing channel, but did not decide to use one.
+    retval = (ParameterUpdateFlags)(retval | eParamChannelChanged);
+    useChannel = false;
+  }
+
+  ///
+  /// Update changed values
+  ///
+
+  if (newType != mType) {
+    retval = (ParameterUpdateFlags)(retval | eParamStateChanged);
+    LOG(("OBJLC [%p]: Type changed from %u -> %u", this, mType, newType));
+    mType = newType;
+  }
+
+  if (!URIEquals(mBaseURI, newBaseURI)) {
+    if (isJava) {
+      // Java bases its class loading on the base URI, so we consider the state
+      // to have changed if this changes. If the object is using a relative URI,
+      // mURI will have changed below regardless
+      retval = (ParameterUpdateFlags)(retval | eParamStateChanged);
+    }
+    LOG(("OBJLC [%p]: Object effective baseURI changed", this));
+    mBaseURI = newBaseURI;
+  }
+
+  if (!URIEquals(newURI, mURI)) {
+    retval = (ParameterUpdateFlags)(retval | eParamStateChanged);
+    LOG(("OBJLC [%p]: Object effective URI changed", this));
+    mURI = newURI;
+  }
+
+  // We don't update content type when loading, as the type is not final and we
+  // don't want to superfluously change between mOriginalContentType ->
+  // mContentType when doing |obj.data = obj.data| with a channel and differing
+  // type.
+  if (mType != eType_Loading && mContentType != newMime) {
+    retval = (ParameterUpdateFlags)(retval | eParamStateChanged);
+    retval = (ParameterUpdateFlags)(retval | eParamContentTypeChanged);
+    LOG(("OBJLC [%p]: Object effective mime type changed (%s -> %s)",
+         this, mContentType.get(), newMime.get()));
+    mContentType = newMime;
+  }
+
+  // If we decided to keep using info from an old channel, but also that state
+  // changed, we need to invalidate it.
+  if (useChannel && !newChannel && (retval & eParamStateChanged)) {
+    mType = eType_Loading;
+    retval = (ParameterUpdateFlags)(retval | eParamChannelChanged);
+  }
+
+  return retval;
+}
+
+// Used by PluginDocument to kick off our initial load from the already-opened
+// channel.
+NS_IMETHODIMP
+nsObjectLoadingContent::InitializeFromChannel(nsIRequest *aChannel)
+{
+  LOG(("OBJLC [%p] InitializeFromChannel: %p", this, aChannel));
+  if (mType != eType_Loading || mChannel) {
+    // We could technically call UnloadObject() here, if consumers have a valid
+    // reason for wanting to call this on an already-loaded tag.
+    NS_NOTREACHED("Should not have begun loading at this point");
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // Because we didn't open this channel from an initial LoadObject, we'll
+  // update our parameters now, so the OnStartRequest->LoadObject doesn't
+  // believe our src/type suddenly changed.
+  UpdateObjectParameters();
+  // But we always want to load from a channel, in this case.
+  mType = eType_Loading;
+  mChannel = do_QueryInterface(aChannel);
+  NS_ASSERTION(mChannel, "passed a request that is not a channel");
+
+  // OnStartRequest will now see we have a channel in the loading state, and
+  // call into LoadObject. There's a possibility LoadObject will decide not to
+  // load anything from a channel - it will call CloseChannel() in that case.
+  return NS_OK;
+}
+
+// Only OnStartRequest should be passing the channel parameter
+nsresult
+nsObjectLoadingContent::LoadObject(bool aNotify,
+                                   bool aForceLoad)
+{
+  return LoadObject(aNotify, aForceLoad, nullptr);
+}
+
+nsresult
+nsObjectLoadingContent::LoadObject(bool aNotify,
+                                   bool aForceLoad,
+                                   nsIRequest *aLoadingChannel)
+{
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  NS_ASSERTION(thisContent, "must be a content");
+  nsIDocument* doc = thisContent->OwnerDoc();
+  nsresult rv = NS_OK;
+
+  // Sanity check
+  if (!InActiveDocument(thisContent)) {
+    NS_NOTREACHED("LoadObject called while not bound to an active document");
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // XXX(johns): In these cases, we refuse to touch our content and just
+  //   remain unloaded, as per legacy behavior. It would make more sense to
+  //   load fallback content initially and refuse to ever change state again.
+  if (doc->IsBeingUsedAsImage() || doc->IsLoadedAsData()) {
+    return NS_OK;
+  }
+
+  LOG(("OBJLC [%p]: LoadObject called, notify %u, forceload %u, channel %p",
+       this, aNotify, aForceLoad, aLoadingChannel));
+
+  // We can't re-use an already open channel, but aForceLoad may make us try
+  // to load a plugin without any changes in channel state.
+  if (aForceLoad && mChannelLoaded) {
+    CloseChannel();
+    mChannelLoaded = false;
+  }
+
+  // Save these for NotifyStateChanged();
+  EventStates oldState = ObjectState();
+  ObjectType oldType = mType;
+
+  ParameterUpdateFlags stateChange = UpdateObjectParameters();
+
+  if (!stateChange && !aForceLoad) {
+    return NS_OK;
+  }
+
+  ///
+  /// State has changed, unload existing content and attempt to load new type
+  ///
+  LOG(("OBJLC [%p]: LoadObject - plugin state changed (%u)",
+       this, stateChange));
+
+  // Setup fallback info. We may also change type to fallback below in case of
+  // sanity/OOM/etc. errors. We default to showing alternate content
+  // NOTE LoadFallback can override this in some cases
+  FallbackType fallbackType = eFallbackAlternate;
+
+  // mType can differ with GetTypeOfContent(mContentType) if we support this
+  // type, but the parameters are invalid e.g. a embed tag with type "image/png"
+  // but no URI -- don't show a plugin error or unknown type error in that case.
+  if (mType == eType_Null && GetTypeOfContent(mContentType) == eType_Null) {
+    fallbackType = eFallbackUnsupported;
+  }
+
+  // Explicit user activation should reset if the object changes content types
+  if (mActivated && (stateChange & eParamContentTypeChanged)) {
+    LOG(("OBJLC [%p]: Content type changed, clearing activation state", this));
+    mActivated = false;
+  }
+
+  // We synchronously start/stop plugin instances below, which may spin the
+  // event loop. Re-entering into the load is fine, but at that point the
+  // original load call needs to abort when unwinding
+  // NOTE this is located *after* the state change check, a subseqent load
+  //      with no subsequently changed state will be a no-op.
+  if (mIsLoading) {
+    LOG(("OBJLC [%p]: Re-entering into LoadObject", this));
+  }
+  mIsLoading = true;
+  AutoSetLoadingToFalse reentryCheck(this);
+
+  // Unload existing content, keeping in mind stopping plugins might spin the
+  // event loop. Note that we check for still-open channels below
+  UnloadObject(false); // Don't reset state
+  if (!mIsLoading) {
+    // The event loop must've spun and re-entered into LoadObject, which
+    // finished the load
+    LOG(("OBJLC [%p]: Re-entered into LoadObject, aborting outer load", this));
+    return NS_OK;
+  }
+
+  // Determine what's going on with our channel.
+  if (stateChange & eParamChannelChanged) {
+    // If the channel params changed, throw away the channel, but unset
+    // mChannelLoaded so we'll still try to open a new one for this load if
+    // necessary
+    CloseChannel();
+    mChannelLoaded = false;
+  } else if (mType == eType_Null && mChannel) {
+    // If we opened a channel but then failed to find a loadable state, throw it
+    // away. mChannelLoaded will indicate that we tried to load a channel at one
+    // point so we wont recurse
+    CloseChannel();
+  } else if (mType == eType_Loading && mChannel) {
+    // We're still waiting on a channel load, already opened one, and
+    // channel parameters didn't change
+    return NS_OK;
+  } else if (mChannelLoaded && mChannel != aLoadingChannel) {
+    // The only time we should have a loaded channel with a changed state is
+    // when the channel has just opened -- in which case this call should
+    // have originated from OnStartRequest
+    NS_NOTREACHED("Loading with a channel, but state doesn't make sense");
+    return NS_OK;
+  }
+
+  //
+  // Security checks
+  //
+
+  if (mType != eType_Null) {
+    bool allowLoad = true;
+    if (IsJavaMIME(mContentType)) {
+      allowLoad = CheckJavaCodebase();
+    }
+    int16_t contentPolicy = nsIContentPolicy::ACCEPT;
+    // If mChannelLoaded is set we presumably already passed load policy
+    // If mType == eType_Loading then we call OpenChannel() which internally
+    // creates a new channel and calls asyncOpen2() on that channel which
+    // then enforces content policy checks.
+    if (allowLoad && mURI && !mChannelLoaded && mType != eType_Loading) {
+      allowLoad = CheckLoadPolicy(&contentPolicy);
+    }
+    // If we're loading a type now, check ProcessPolicy. Note that we may check
+    // both now in the case of plugins whose type is determined before opening a
+    // channel.
+    if (allowLoad && mType != eType_Loading) {
+      allowLoad = CheckProcessPolicy(&contentPolicy);
+    }
+
+    // Content policy implementations can mutate the DOM, check for re-entry
+    if (!mIsLoading) {
+      LOG(("OBJLC [%p]: We re-entered in content policy, leaving original load",
+           this));
+      return NS_OK;
+    }
+
+    // Load denied, switch to fallback and set disabled/suppressed if applicable
+    if (!allowLoad) {
+      LOG(("OBJLC [%p]: Load denied by policy", this));
+      mType = eType_Null;
+      if (contentPolicy == nsIContentPolicy::REJECT_TYPE) {
+        // XXX(johns) This is assuming that we were rejected by
+        //            nsContentBlocker, which rejects by type if permissions
+        //            reject plugins
+        fallbackType = eFallbackUserDisabled;
+      } else {
+        fallbackType = eFallbackSuppressed;
+      }
+    }
+  }
+
+  // Don't allow view-source scheme.
+  // view-source is the only scheme to which this applies at the moment due to
+  // potential timing attacks to read data from cross-origin documents. If this
+  // widens we should add a protocol flag for whether the scheme is only allowed
+  // in top and use something like nsNetUtil::NS_URIChainHasFlags.
+  if (mType != eType_Null) {
+    nsCOMPtr<nsIURI> tempURI = mURI;
+    nsCOMPtr<nsINestedURI> nestedURI = do_QueryInterface(tempURI);
+    while (nestedURI) {
+      // view-source should always be an nsINestedURI, loop and check the
+      // scheme on this and all inner URIs that are also nested URIs.
+      bool isViewSource = false;
+      rv = tempURI->SchemeIs("view-source", &isViewSource);
+      if (NS_FAILED(rv) || isViewSource) {
+        LOG(("OBJLC [%p]: Blocking as effective URI has view-source scheme",
+             this));
+        mType = eType_Null;
+        break;
+      }
+
+      nestedURI->GetInnerURI(getter_AddRefs(tempURI));
+      nestedURI = do_QueryInterface(tempURI);
+    }
+  }
+
+  // Items resolved as Image/Document are no candidates for content blocking,
+  // as well as invalid plugins (they will not have the mContentType set).
+  if ((mType == eType_Null || mType == eType_Plugin) && ShouldBlockContent()) {
+    LOG(("OBJLC [%p]: Enable content blocking", this));
+    mType = eType_Loading;
+  }
+
+  // If we're a plugin but shouldn't start yet, load fallback with
+  // reason click-to-play instead. Items resolved as Image/Document
+  // will not be checked for previews, as well as invalid plugins
+  // (they will not have the mContentType set).
+  FallbackType clickToPlayReason;
+  if (!mActivated && (mType == eType_Null || mType == eType_Plugin) &&
+      !ShouldPlay(clickToPlayReason, false)) {
+    LOG(("OBJLC [%p]: Marking plugin as click-to-play", this));
+    mType = eType_Null;
+    fallbackType = clickToPlayReason;
+  }
+
+  if (!mActivated && mType == eType_Plugin) {
+    // Object passed ShouldPlay, so it should be considered
+    // activated until it changes content type
+    LOG(("OBJLC [%p]: Object implicitly activated", this));
+    mActivated = true;
+  }
+
+  // Sanity check: We shouldn't have any loaded resources, pending events, or
+  // a final listener at this point
+  if (mFrameLoader || mPendingInstantiateEvent || mInstanceOwner ||
+      mPendingCheckPluginStopEvent || mFinalListener)
+  {
+    NS_NOTREACHED("Trying to load new plugin with existing content");
+    rv = NS_ERROR_UNEXPECTED;
+    return NS_OK;
+  }
+
+  // More sanity-checking:
+  // If mChannel is set, mChannelLoaded should be set, and vice-versa
+  if (mType != eType_Null && !!mChannel != mChannelLoaded) {
+    NS_NOTREACHED("Trying to load with bad channel state");
+    rv = NS_ERROR_UNEXPECTED;
+    return NS_OK;
+  }
+
+  ///
+  /// Attempt to load new type
+  ///
+
+
+  // Cache the current attributes and parameters.
+  if (mType == eType_Plugin || mType == eType_Null) {
+    rv = BuildParametersArray();
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  // We don't set mFinalListener until OnStartRequest has been called, to
+  // prevent re-entry ugliness with CloseChannel()
+  nsCOMPtr<nsIStreamListener> finalListener;
+  // If we decide to synchronously spawn a plugin, we do it after firing
+  // notifications to avoid re-entry causing notifications to fire out of order.
+  bool doSpawnPlugin = false;
+  switch (mType) {
+    case eType_Image:
+      if (!mChannel) {
+        // We have a LoadImage() call, but UpdateObjectParameters requires a
+        // channel for images, so this is not a valid state.
+        NS_NOTREACHED("Attempting to load image without a channel?");
+        rv = NS_ERROR_UNEXPECTED;
+        break;
+      }
+      rv = LoadImageWithChannel(mChannel, getter_AddRefs(finalListener));
+      // finalListener will receive OnStartRequest below
+    break;
+    case eType_Plugin:
+    {
+      if (mChannel) {
+        // Force a sync state change now, we need the frame created
+        NotifyStateChanged(oldType, oldState, true, aNotify);
+        oldType = mType;
+        oldState = ObjectState();
+
+        if (!thisContent->GetPrimaryFrame()) {
+          // We're un-rendered, and can't instantiate a plugin. HasNewFrame will
+          // re-start us when we can proceed.
+          LOG(("OBJLC [%p]: Aborting load - plugin-type, but no frame", this));
+          CloseChannel();
+          break;
+        }
+
+        // We'll handle this below
+        doSpawnPlugin = true;
+      } else {
+        rv = AsyncStartPluginInstance();
+      }
+    }
+    break;
+    case eType_Document:
+    {
+      if (!mChannel) {
+        // We could mFrameLoader->LoadURI(mURI), but UpdateObjectParameters
+        // requires documents have a channel, so this is not a valid state.
+        NS_NOTREACHED("Attempting to load a document without a channel");
+        mType = eType_Null;
+        break;
+      }
+
+      mFrameLoader = nsFrameLoader::Create(thisContent->AsElement(),
+                                           /* aOpener = */ nullptr,
+                                           mNetworkCreated);
+      if (!mFrameLoader) {
+        NS_NOTREACHED("nsFrameLoader::Create failed");
+        mType = eType_Null;
+        break;
+      }
+
+      rv = mFrameLoader->CheckForRecursiveLoad(mURI);
+      if (NS_FAILED(rv)) {
+        LOG(("OBJLC [%p]: Aborting recursive load", this));
+        mFrameLoader->Destroy();
+        mFrameLoader = nullptr;
+        mType = eType_Null;
+        break;
+      }
+
+      // We're loading a document, so we have to set LOAD_DOCUMENT_URI
+      // (especially important for firing onload)
+      nsLoadFlags flags = 0;
+      mChannel->GetLoadFlags(&flags);
+      flags |= nsIChannel::LOAD_DOCUMENT_URI;
+      mChannel->SetLoadFlags(flags);
+
+      nsCOMPtr<nsIDocShell> docShell;
+      rv = mFrameLoader->GetDocShell(getter_AddRefs(docShell));
+      if (NS_FAILED(rv)) {
+        NS_NOTREACHED("Could not get DocShell from mFrameLoader?");
+        mType = eType_Null;
+        break;
+      }
+
+      nsCOMPtr<nsIInterfaceRequestor> req(do_QueryInterface(docShell));
+      NS_ASSERTION(req, "Docshell must be an ifreq");
+
+      nsCOMPtr<nsIURILoader>
+        uriLoader(do_GetService(NS_URI_LOADER_CONTRACTID, &rv));
+      if (NS_FAILED(rv)) {
+        NS_NOTREACHED("Failed to get uriLoader service");
+        mType = eType_Null;
+        break;
+      }
+      rv = uriLoader->OpenChannel(mChannel, nsIURILoader::DONT_RETARGET, req,
+                                  getter_AddRefs(finalListener));
+      // finalListener will receive OnStartRequest below
+    }
+    break;
+    case eType_Loading:
+      // If our type remains Loading, we need a channel to proceed
+      rv = OpenChannel();
+      if (NS_FAILED(rv)) {
+        LOG(("OBJLC [%p]: OpenChannel returned failure (%u)", this, rv));
+      }
+    break;
+    case eType_Null:
+      // Handled below, silence compiler warnings
+    break;
+  }
+
+  //
+  // Loaded, handle notifications and fallback
+  //
+  if (NS_FAILED(rv)) {
+    // If we failed in the loading hunk above, switch to fallback
+    LOG(("OBJLC [%p]: Loading failed, switching to fallback", this));
+    mType = eType_Null;
+  }
+
+  // If we didn't load anything, handle switching to fallback state
+  if (mType == eType_Null) {
+    LOG(("OBJLC [%p]: Loading fallback, type %u", this, fallbackType));
+    NS_ASSERTION(!mFrameLoader && !mInstanceOwner,
+                 "switched to type null but also loaded something");
+
+    // Don't fire error events if we're falling back to click-to-play; instead
+    // pretend like this is a really slow-loading plug-in instead.
+    if (fallbackType != eFallbackClickToPlay) {
+      MaybeFireErrorEvent();
+    }
+
+    if (mChannel) {
+      // If we were loading with a channel but then failed over, throw it away
+      CloseChannel();
+    }
+
+    // Don't try to initialize plugins or final listener below
+    doSpawnPlugin = false;
+    finalListener = nullptr;
+
+    // Don't notify, as LoadFallback doesn't know of our previous state
+    // (so really this is just setting mFallbackType)
+    LoadFallback(fallbackType, false);
+  }
+
+  // Notify of our final state
+  NotifyStateChanged(oldType, oldState, false, aNotify);
+  NS_ENSURE_TRUE(mIsLoading, NS_OK);
+
+
+  //
+  // Spawning plugins and dispatching to the final listener may re-enter, so are
+  // delayed until after we fire a notification, to prevent missing
+  // notifications or firing them out of order.
+  //
+  // Note that we ensured that we entered into LoadObject() from
+  // ::OnStartRequest above when loading with a channel.
+  //
+
+  rv = NS_OK;
+  if (doSpawnPlugin) {
+    rv = InstantiatePluginInstance(true);
+    NS_ENSURE_TRUE(mIsLoading, NS_OK);
+    // Create the final listener if we're loading with a channel. We can't do
+    // this in the loading block above as it requires an instance.
+    if (aLoadingChannel && NS_SUCCEEDED(rv)) {
+      if (NS_SUCCEEDED(rv) && MakePluginListener()) {
+        rv = mFinalListener->OnStartRequest(mChannel, nullptr);
+        if (NS_FAILED(rv)) {
+          // Plugins can reject their initial stream, but continue to run.
+          CloseChannel();
+          NS_ENSURE_TRUE(mIsLoading, NS_OK);
+          rv = NS_OK;
+        }
+      }
+    }
+  } else if (finalListener) {
+    NS_ASSERTION(mType != eType_Null && mType != eType_Loading,
+                 "We should not have a final listener with a non-loaded type");
+    mFinalListener = finalListener;
+    rv = finalListener->OnStartRequest(mChannel, nullptr);
+  }
+
+  if (NS_FAILED(rv) && mIsLoading) {
+    // Since we've already notified of our transition, we can just Unload and
+    // call LoadFallback (which will notify again)
+    mType = eType_Null;
+    UnloadObject(false);
+    NS_ENSURE_TRUE(mIsLoading, NS_OK);
+    CloseChannel();
+    LoadFallback(fallbackType, true);
+  }
+
+  return NS_OK;
+}
+
+// This call can re-enter when dealing with plugin listeners
+nsresult
+nsObjectLoadingContent::CloseChannel()
+{
+  if (mChannel) {
+    LOG(("OBJLC [%p]: Closing channel\n", this));
+    // Null the values before potentially-reentering, and ensure they survive
+    // the call
+    nsCOMPtr<nsIChannel> channelGrip(mChannel);
+    nsCOMPtr<nsIStreamListener> listenerGrip(mFinalListener);
+    mChannel = nullptr;
+    mFinalListener = nullptr;
+    channelGrip->Cancel(NS_BINDING_ABORTED);
+    if (listenerGrip) {
+      // mFinalListener is only set by LoadObject after OnStartRequest, or
+      // by OnStartRequest in the case of late-opened plugin streams
+      listenerGrip->OnStopRequest(channelGrip, nullptr, NS_BINDING_ABORTED);
+    }
+  }
+  return NS_OK;
+}
+
+nsresult
+nsObjectLoadingContent::OpenChannel()
+{
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  NS_ASSERTION(thisContent, "must be a content");
+  nsIDocument* doc = thisContent->OwnerDoc();
+  NS_ASSERTION(doc, "No owner document?");
+
+  nsresult rv;
+  mChannel = nullptr;
+
+  // E.g. mms://
+  if (!mURI || !CanHandleURI(mURI)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsCOMPtr<nsILoadGroup> group = doc->GetDocumentLoadGroup();
+  nsCOMPtr<nsIChannel> chan;
+  RefPtr<ObjectInterfaceRequestorShim> shim =
+    new ObjectInterfaceRequestorShim(this);
+
+  bool isSandBoxed = doc->GetSandboxFlags() & SANDBOXED_ORIGIN;
+  bool inherit = nsContentUtils::ChannelShouldInheritPrincipal(thisContent->NodePrincipal(),
+                                                               mURI,
+                                                               true,   // aInheritForAboutBlank
+                                                               false); // aForceInherit
+  nsSecurityFlags securityFlags = nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_INHERITS;
+  if (inherit) {
+    securityFlags |= nsILoadInfo::SEC_FORCE_INHERIT_PRINCIPAL;
+  }
+  if (isSandBoxed) {
+    securityFlags |= nsILoadInfo::SEC_SANDBOXED;
+  }
+
+  nsContentPolicyType contentPolicyType = GetContentPolicyType();
+
+  rv = NS_NewChannel(getter_AddRefs(chan),
+                     mURI,
+                     thisContent,
+                     securityFlags,
+                     contentPolicyType,
+                     group, // aLoadGroup
+                     shim,  // aCallbacks
+                     nsIChannel::LOAD_CALL_CONTENT_SNIFFERS |
+                     nsIChannel::LOAD_CLASSIFY_URI |
+                     nsIChannel::LOAD_BYPASS_SERVICE_WORKER);
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (inherit) {
+    nsCOMPtr<nsILoadInfo> loadinfo = chan->GetLoadInfo();
+    loadinfo->SetPrincipalToInherit(thisContent->NodePrincipal());
+  }
+
+  // Referrer
+  nsCOMPtr<nsIHttpChannel> httpChan(do_QueryInterface(chan));
+  if (httpChan) {
+    httpChan->SetReferrerWithPolicy(doc->GetDocumentURI(),
+                                    doc->GetReferrerPolicy());
+
+    // Set the initiator type
+    nsCOMPtr<nsITimedChannel> timedChannel(do_QueryInterface(httpChan));
+    if (timedChannel) {
+      timedChannel->SetInitiatorType(thisContent->LocalName());
+    }
+  }
+
+  nsCOMPtr<nsIScriptChannel> scriptChannel = do_QueryInterface(chan);
+  if (scriptChannel) {
+    // Allow execution against our context if the principals match
+    scriptChannel->SetExecutionPolicy(nsIScriptChannel::EXECUTE_NORMAL);
+  }
+
+  // AsyncOpen2 can fail if a file does not exist.
+  rv = chan->AsyncOpen2(shim);
+  NS_ENSURE_SUCCESS(rv, rv);
+  LOG(("OBJLC [%p]: Channel opened", this));
+  mChannel = chan;
+  return NS_OK;
+}
+
+uint32_t
+nsObjectLoadingContent::GetCapabilities() const
+{
+  return eSupportImages |
+         eSupportPlugins |
+         eSupportDocuments;
+}
+
+void
+nsObjectLoadingContent::DestroyContent()
+{
+  if (mFrameLoader) {
+    mFrameLoader->Destroy();
+    mFrameLoader = nullptr;
+  }
+
+  if (mInstanceOwner || mInstantiating) {
+    QueueCheckPluginStopEvent();
+  }
+}
+
+/* static */
+void
+nsObjectLoadingContent::Traverse(nsObjectLoadingContent *tmp,
+                                 nsCycleCollectionTraversalCallback &cb)
+{
+  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mFrameLoader");
+  cb.NoteXPCOMChild(static_cast<nsIFrameLoader*>(tmp->mFrameLoader));
+}
+
+void
+nsObjectLoadingContent::UnloadObject(bool aResetState)
+{
+  // Don't notify in CancelImageRequests until we transition to a new loaded
+  // state
+  CancelImageRequests(false);
+  if (mFrameLoader) {
+    mFrameLoader->Destroy();
+    mFrameLoader = nullptr;
+  }
+
+  if (aResetState) {
+    if (mType != eType_Plugin) {
+      // This can re-enter when dealing with plugins, and StopPluginInstance
+      // will handle it
+      CloseChannel();
+    }
+    mChannelLoaded = false;
+    mType = eType_Loading;
+    mURI = mOriginalURI = mBaseURI = nullptr;
+    mContentType.Truncate();
+    mOriginalContentType.Truncate();
+  }
+
+  // InstantiatePluginInstance checks this after re-entrant calls and aborts if
+  // it was cleared from under it
+  mInstantiating = false;
+
+  mScriptRequested = false;
+
+  if (mIsStopping) {
+    // The protochain is normally thrown out after a plugin stops, but if we
+    // re-enter while stopping a plugin and try to load something new, we need
+    // to throw away the old protochain in the nested unload.
+    TeardownProtoChain();
+    mIsStopping = false;
+  }
+
+  mCachedAttributes.Clear();
+  mCachedParameters.Clear();
+
+  // This call should be last as it may re-enter
+  StopPluginInstance();
+}
+
+void
+nsObjectLoadingContent::NotifyStateChanged(ObjectType aOldType,
+                                           EventStates aOldState,
+                                           bool aSync,
+                                           bool aNotify)
+{
+  LOG(("OBJLC [%p]: Notifying about state change: (%u, %llx) -> (%u, %llx)"
+       " (sync %i, notify %i)", this, aOldType, aOldState.GetInternalValue(),
+       mType, ObjectState().GetInternalValue(), aSync, aNotify));
+
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  NS_ASSERTION(thisContent, "must be a content");
+
+  NS_ASSERTION(thisContent->IsElement(), "Not an element?");
+
+  // XXX(johns): A good bit of the code below replicates UpdateState(true)
+
+  // Unfortunately, we do some state changes without notifying
+  // (e.g. in Fallback when canceling image requests), so we have to
+  // manually notify object state changes.
+  thisContent->AsElement()->UpdateState(false);
+
+  if (!aNotify) {
+    // We're done here
+    return;
+  }
+
+  nsIDocument* doc = thisContent->GetComposedDoc();
+  if (!doc) {
+    return; // Nothing to do
+  }
+
+  EventStates newState = ObjectState();
+
+  if (newState != aOldState) {
+    NS_ASSERTION(thisContent->IsInComposedDoc(), "Something is confused");
+    // This will trigger frame construction
+    EventStates changedBits = aOldState ^ newState;
+
+    {
+      nsAutoScriptBlocker scriptBlocker;
+      doc->ContentStateChanged(thisContent, changedBits);
+    }
+    if (aSync) {
+      NS_ASSERTION(InActiveDocument(thisContent), "Something is confused");
+      // Make sure that frames are actually constructed immediately.
+      doc->FlushPendingNotifications(Flush_Frames);
+    }
+  } else if (aOldType != mType) {
+    // If our state changed, then we already recreated frames
+    // Otherwise, need to do that here
+    nsCOMPtr<nsIPresShell> shell = doc->GetShell();
+    if (shell) {
+      shell->RecreateFramesFor(thisContent);
+    }
+  }
+}
+
+nsObjectLoadingContent::ObjectType
+nsObjectLoadingContent::GetTypeOfContent(const nsCString& aMIMEType)
+{
+  if (aMIMEType.IsEmpty()) {
+    return eType_Null;
+  }
+
+  uint32_t caps = GetCapabilities();
+
+  if ((caps & eSupportImages) && IsSupportedImage(aMIMEType)) {
+    return eType_Image;
+  }
+
+  // Faking support of the PDF content as a document for EMBED tags
+  // when internal PDF viewer is enabled.
+  if (aMIMEType.LowerCaseEqualsLiteral("application/pdf") &&
+      nsContentUtils::IsPDFJSEnabled()) {
+    return eType_Document;
+  }
+
+  // Faking support of the SWF content as a document for EMBED tags
+  // when internal SWF player is enabled.
+  if (aMIMEType.LowerCaseEqualsLiteral("application/x-shockwave-flash") &&
+      nsContentUtils::IsSWFPlayerEnabled()) {
+    return eType_Document;
+  }
+
+  if ((caps & eSupportDocuments) && IsSupportedDocument(aMIMEType)) {
+    return eType_Document;
+  }
+
+  RefPtr<nsPluginHost> pluginHost = nsPluginHost::GetInst();
+  if ((caps & eSupportPlugins) &&
+      pluginHost &&
+      pluginHost->HavePluginForType(aMIMEType, nsPluginHost::eExcludeNone)) {
+    // ShouldPlay will handle checking for disabled plugins
+    return eType_Plugin;
+  }
+
+  return eType_Null;
+}
+
+nsPluginFrame*
+nsObjectLoadingContent::GetExistingFrame()
+{
+  nsCOMPtr<nsIContent> thisContent = do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  nsIFrame* frame = thisContent->GetPrimaryFrame();
+  nsIObjectFrame* objFrame = do_QueryFrame(frame);
+  return static_cast<nsPluginFrame*>(objFrame);
+}
+
+void
+nsObjectLoadingContent::CreateStaticClone(nsObjectLoadingContent* aDest) const
+{
+  nsImageLoadingContent::CreateStaticImageClone(aDest);
+
+  aDest->mType = mType;
+  nsObjectLoadingContent* thisObj = const_cast<nsObjectLoadingContent*>(this);
+  if (thisObj->mPrintFrame.IsAlive()) {
+    aDest->mPrintFrame = thisObj->mPrintFrame;
+  } else {
+    aDest->mPrintFrame = const_cast<nsObjectLoadingContent*>(this)->GetExistingFrame();
+  }
+
+  if (mFrameLoader) {
+    nsCOMPtr<nsIContent> content =
+      do_QueryInterface(static_cast<nsIImageLoadingContent*>(aDest));
+    nsFrameLoader* fl = nsFrameLoader::Create(content->AsElement(), nullptr, false);
+    if (fl) {
+      aDest->mFrameLoader = fl;
+      mFrameLoader->CreateStaticClone(fl);
+    }
+  }
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetPrintFrame(nsIFrame** aFrame)
+{
+  *aFrame = mPrintFrame.GetFrame();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::PluginDestroyed()
+{
+  // Called when our plugin is destroyed from under us, usually when reloading
+  // plugins in plugin host. Invalidate instance owner / prototype but otherwise
+  // don't take any action.
+  TeardownProtoChain();
+  if (mInstanceOwner) {
+    mInstanceOwner->Destroy();
+    mInstanceOwner = nullptr;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::PluginCrashed(nsIPluginTag* aPluginTag,
+                                      const nsAString& pluginDumpID,
+                                      const nsAString& browserDumpID,
+                                      bool submittedCrashReport)
+{
+  LOG(("OBJLC [%p]: Plugin Crashed, queuing crash event", this));
+  NS_ASSERTION(mType == eType_Plugin, "PluginCrashed at non-plugin type");
+
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+
+#ifdef XP_MACOSX
+  HTMLObjectElement::HandlePluginCrashed(thisContent->AsElement());
+#endif
+
+  PluginDestroyed();
+
+  // Switch to fallback/crashed state, notify
+  LoadFallback(eFallbackCrashed, true);
+
+  // send nsPluginCrashedEvent
+
+  // Note that aPluginTag in invalidated after we're called, so copy
+  // out any data we need now.
+  nsAutoCString pluginName;
+  aPluginTag->GetName(pluginName);
+  nsAutoCString pluginFilename;
+  aPluginTag->GetFilename(pluginFilename);
+
+  nsCOMPtr<nsIRunnable> ev =
+    new nsPluginCrashedEvent(thisContent,
+                             pluginDumpID,
+                             browserDumpID,
+                             NS_ConvertUTF8toUTF16(pluginName),
+                             NS_ConvertUTF8toUTF16(pluginFilename),
+                             submittedCrashReport);
+  nsresult rv = NS_DispatchToCurrentThread(ev);
+  if (NS_FAILED(rv)) {
+    NS_WARNING("failed to dispatch nsPluginCrashedEvent");
+  }
+  return NS_OK;
+}
+
+nsresult
+nsObjectLoadingContent::ScriptRequestPluginInstance(JSContext* aCx,
+                                                    nsNPAPIPluginInstance **aResult)
+{
+  // The below methods pull the cx off the stack, so make sure they match.
+  //
+  // NB: Sometimes there's a null cx on the stack, in which case |cx| is the
+  // safe JS context. But in that case, IsCallerChrome() will return true,
+  // so the ensuing expression is short-circuited.
+  MOZ_ASSERT_IF(nsContentUtils::GetCurrentJSContext(),
+                aCx == nsContentUtils::GetCurrentJSContext());
+  bool callerIsContentJS = (nsContentUtils::GetCurrentJSContext() &&
+                            !nsContentUtils::IsCallerChrome() &&
+                            !nsContentUtils::IsCallerContentXBL());
+
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+
+  *aResult = nullptr;
+
+  // The first time content script attempts to access placeholder content, fire
+  // an event.  Fallback types >= eFallbackClickToPlay are plugin-replacement
+  // types, see header.
+  if (callerIsContentJS && !mScriptRequested &&
+      InActiveDocument(thisContent) && mType == eType_Null &&
+      mFallbackType >= eFallbackClickToPlay) {
+    nsCOMPtr<nsIRunnable> ev =
+      new nsSimplePluginEvent(thisContent,
+                              NS_LITERAL_STRING("PluginScripted"));
+    nsresult rv = NS_DispatchToCurrentThread(ev);
+    if (NS_FAILED(rv)) {
+      NS_NOTREACHED("failed to dispatch PluginScripted event");
+    }
+    mScriptRequested = true;
+  } else if (callerIsContentJS && mType == eType_Plugin && !mInstanceOwner &&
+             nsContentUtils::IsSafeToRunScript() &&
+             InActiveDocument(thisContent)) {
+    // If we're configured as a plugin in an active document and it's safe to
+    // run scripts right now, try spawning synchronously
+    SyncStartPluginInstance();
+  }
+
+  if (mInstanceOwner) {
+    return mInstanceOwner->GetInstance(aResult);
+  }
+
+  // Note that returning a null plugin is expected (and happens often)
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::SyncStartPluginInstance()
+{
+  NS_ASSERTION(nsContentUtils::IsSafeToRunScript(),
+               "Must be able to run script in order to instantiate a plugin instance!");
+
+  // Don't even attempt to start an instance unless the content is in
+  // the document and active
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  if (!InActiveDocument(thisContent)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsIURI> kungFuURIGrip(mURI);
+  mozilla::Unused << kungFuURIGrip; // This URI is not referred to within this function
+  nsCString contentType(mContentType);
+  return InstantiatePluginInstance();
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::AsyncStartPluginInstance()
+{
+  // OK to have an instance already or a pending spawn.
+  if (mInstanceOwner || mPendingInstantiateEvent) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  nsIDocument* doc = thisContent->OwnerDoc();
+  if (doc->IsStaticDocument() || doc->IsBeingUsedAsImage()) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIRunnable> event = new nsAsyncInstantiateEvent(this);
+  nsresult rv = NS_DispatchToCurrentThread(event);
+  if (NS_SUCCEEDED(rv)) {
+    // Track pending events
+    mPendingInstantiateEvent = event;
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetSrcURI(nsIURI** aURI)
+{
+  NS_IF_ADDREF(*aURI = GetSrcURI());
+  return NS_OK;
+}
+
+static bool
+DoDelayedStop(nsPluginInstanceOwner* aInstanceOwner,
+              nsObjectLoadingContent* aContent,
+              bool aDelayedStop)
+{
+  // Don't delay stopping QuickTime (bug 425157), Flip4Mac (bug 426524),
+  // XStandard (bug 430219), CMISS Zinc (bug 429604).
+  if (aDelayedStop
+#if !(defined XP_WIN || defined MOZ_X11)
+      && !aInstanceOwner->MatchPluginName("QuickTime")
+      && !aInstanceOwner->MatchPluginName("Flip4Mac")
+      && !aInstanceOwner->MatchPluginName("XStandard plugin")
+      && !aInstanceOwner->MatchPluginName("CMISS Zinc Plugin")
+#endif
+      ) {
+    nsCOMPtr<nsIRunnable> evt =
+      new nsStopPluginRunnable(aInstanceOwner, aContent);
+    NS_DispatchToCurrentThread(evt);
+    return true;
+  }
+  return false;
+}
+
+void
+nsObjectLoadingContent::LoadFallback(FallbackType aType, bool aNotify) {
+  EventStates oldState = ObjectState();
+  ObjectType oldType = mType;
+
+  NS_ASSERTION(!mInstanceOwner && !mFrameLoader && !mChannel,
+               "LoadFallback called with loaded content");
+
+  //
+  // Fixup mFallbackType
+  //
+  nsCOMPtr<nsIContent> thisContent =
+  do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  NS_ASSERTION(thisContent, "must be a content");
+
+  if (!thisContent->IsHTMLElement() || mContentType.IsEmpty()) {
+    // Don't let custom fallback handlers run outside HTML, tags without a
+    // determined type should always just be alternate content
+    aType = eFallbackAlternate;
+  }
+
+  // We'll set this to null no matter what now, doing it here means we'll load
+  // child embeds as we find them in the upcoming loop.
+  mType = eType_Null;
+
+  // Do a breadth-first traverse of node tree with the current element as root,
+  // looking for the first embed we can find.
+  nsTArray<nsINodeList*> childNodes;
+  if ((thisContent->IsHTMLElement(nsGkAtoms::object) ||
+       thisContent->IsHTMLElement(nsGkAtoms::applet)) &&
+      (aType == eFallbackUnsupported ||
+       aType == eFallbackDisabled ||
+       aType == eFallbackBlocklisted ||
+       aType == eFallbackAlternate))
+  {
+    for (nsIContent* child = thisContent->GetFirstChild(); child;
+         child = child->GetNextNode(thisContent)) {
+      if (aType != eFallbackAlternate &&
+          !child->IsHTMLElement(nsGkAtoms::param) &&
+          nsStyleUtil::IsSignificantChild(child, true, false)) {
+        aType = eFallbackAlternate;
+      }
+      if (child->IsHTMLElement(nsGkAtoms::embed) &&
+          thisContent->IsHTMLElement(nsGkAtoms::object)) {
+        HTMLSharedObjectElement* object = static_cast<HTMLSharedObjectElement*>(child);
+        if (object) {
+          object->StartObjectLoad(true, true);
+        }
+      }
+    }
+  }
+
+  mFallbackType = aType;
+
+  // Notify
+  if (!aNotify) {
+    return; // done
+  }
+
+  NotifyStateChanged(oldType, oldState, false, true);
+}
+
+void
+nsObjectLoadingContent::DoStopPlugin(nsPluginInstanceOwner* aInstanceOwner,
+                                     bool aDelayedStop,
+                                     bool aForcedReentry)
+{
+  // DoStopPlugin can process events -- There may be pending
+  // CheckPluginStopEvent events which can drop in underneath us and destroy the
+  // instance we are about to destroy. We prevent that with the mPluginStopping
+  // flag.  (aForcedReentry is only true from the callback of an earlier delayed
+  // stop)
+  if (mIsStopping && !aForcedReentry) {
+    return;
+  }
+  mIsStopping = true;
+
+  RefPtr<nsPluginInstanceOwner> kungFuDeathGrip(aInstanceOwner);
+  RefPtr<nsNPAPIPluginInstance> inst;
+  aInstanceOwner->GetInstance(getter_AddRefs(inst));
+  if (inst) {
+    if (DoDelayedStop(aInstanceOwner, this, aDelayedStop)) {
+      return;
+    }
+
+#if defined(XP_MACOSX)
+    aInstanceOwner->HidePluginWindow();
+#endif
+
+    RefPtr<nsPluginHost> pluginHost = nsPluginHost::GetInst();
+    NS_ASSERTION(pluginHost, "No plugin host?");
+    pluginHost->StopPluginInstance(inst);
+  }
+
+  aInstanceOwner->Destroy();
+
+  // If we re-enter in plugin teardown UnloadObject will tear down the
+  // protochain -- the current protochain could be from a new, unrelated, load.
+  if (!mIsStopping) {
+    LOG(("OBJLC [%p]: Re-entered in plugin teardown", this));
+    return;
+  }
+
+  TeardownProtoChain();
+  mIsStopping = false;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::StopPluginInstance()
+{
+  PROFILER_LABEL_FUNC(js::ProfileEntry::Category::OTHER);
+  // Clear any pending events
+  mPendingInstantiateEvent = nullptr;
+  mPendingCheckPluginStopEvent = nullptr;
+
+  // If we're currently instantiating, clearing this will cause
+  // InstantiatePluginInstance's re-entrance check to destroy the created plugin
+  mInstantiating = false;
+
+  if (!mInstanceOwner) {
+    return NS_OK;
+  }
+
+  if (mChannel) {
+    // The plugin has already used data from this channel, we'll need to
+    // re-open it to handle instantiating again, even if we don't invalidate
+    // our loaded state.
+    /// XXX(johns): Except currently, we don't, just leaving re-opening channels
+    ///             to plugins...
+    LOG(("OBJLC [%p]: StopPluginInstance - Closing used channel", this));
+    CloseChannel();
+  }
+
+  // We detach the instance owner's frame before destruction, but don't destroy
+  // the instance owner until the plugin is stopped.
+  mInstanceOwner->SetFrame(nullptr);
+
+  bool delayedStop = false;
+#ifdef XP_WIN
+  // Force delayed stop for Real plugin only; see bug 420886, 426852.
+  RefPtr<nsNPAPIPluginInstance> inst;
+  mInstanceOwner->GetInstance(getter_AddRefs(inst));
+  if (inst) {
+    const char* mime = nullptr;
+    if (NS_SUCCEEDED(inst->GetMIMEType(&mime)) && mime) {
+      if (nsPluginHost::GetSpecialType(nsDependentCString(mime)) ==
+          nsPluginHost::eSpecialType_RealPlayer) {
+        delayedStop = true;
+      }
+    }
+  }
+#endif
+
+  RefPtr<nsPluginInstanceOwner> ownerGrip(mInstanceOwner);
+  mInstanceOwner = nullptr;
+
+  // This can/will re-enter
+  DoStopPlugin(ownerGrip, delayedStop);
+
+  return NS_OK;
+}
+
+void
+nsObjectLoadingContent::NotifyContentObjectWrapper()
+{
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+
+  AutoJSAPI jsapi;
+  jsapi.Init();
+  JSContext* cx = jsapi.cx();
+
+  JS::Rooted<JSObject*> obj(cx, thisContent->GetWrapper());
+  if (!obj) {
+    // Nothing to do here if there's no wrapper for mContent. The proto
+    // chain will be fixed appropriately when the wrapper is created.
+    return;
+  }
+
+  SetupProtoChain(cx, obj);
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::PlayPlugin()
+{
+  if (!nsContentUtils::IsCallerChrome())
+    return NS_OK;
+
+  if (!mActivated) {
+    mActivated = true;
+    LOG(("OBJLC [%p]: Activated by user", this));
+  }
+
+  // If we're in a click-to-play state, reload.
+  // Fallback types >= eFallbackClickToPlay are plugin-replacement types, see
+  // header
+  if (mType == eType_Null && mFallbackType >= eFallbackClickToPlay) {
+    return LoadObject(true, true);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::Reload(bool aClearActivation)
+{
+  if (aClearActivation) {
+    mActivated = false;
+  }
+
+  return LoadObject(true, true);
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetActivated(bool *aActivated)
+{
+  *aActivated = Activated();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetPluginFallbackType(uint32_t* aPluginFallbackType)
+{
+  NS_ENSURE_TRUE(nsContentUtils::IsCallerChrome(), NS_ERROR_NOT_AVAILABLE);
+  *aPluginFallbackType = mFallbackType;
+  return NS_OK;
+}
+
+uint32_t
+nsObjectLoadingContent::DefaultFallbackType()
+{
+  FallbackType reason;
+  bool go = ShouldPlay(reason, true);
+  if (go) {
+    return PLUGIN_ACTIVE;
+  }
+  return reason;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetHasRunningPlugin(bool *aHasPlugin)
+{
+  NS_ENSURE_TRUE(nsContentUtils::IsCallerChrome(), NS_ERROR_NOT_AVAILABLE);
+  *aHasPlugin = HasRunningPlugin();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::GetRunID(uint32_t* aRunID)
+{
+  if (NS_WARN_IF(!nsContentUtils::IsCallerChrome())) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  if (NS_WARN_IF(!aRunID)) {
+    return NS_ERROR_INVALID_POINTER;
+  }
+  if (!mHasRunID) {
+    // The plugin instance must not have a run ID, so we must
+    // be running the plugin in-process.
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+  *aRunID = mRunID;
+  return NS_OK;
+}
+
+static bool sPrefsInitialized;
+static uint32_t sSessionTimeoutMinutes;
+static uint32_t sPersistentTimeoutDays;
+static bool sBlockURIs;
+
+static void initializeObjectLoadingContentPrefs()
+{
+  if (!sPrefsInitialized) {
+    Preferences::AddUintVarCache(&sSessionTimeoutMinutes,
+                                 "plugin.sessionPermissionNow.intervalInMinutes", 60);
+    Preferences::AddUintVarCache(&sPersistentTimeoutDays,
+                                 "plugin.persistentPermissionAlways.intervalInDays", 90);
+
+    Preferences::AddBoolVarCache(&sBlockURIs, kPrefBlockURIs, false);
+    sPrefsInitialized = true;
+  }
+}
+
+bool
+nsObjectLoadingContent::ShouldBlockContent()
+{
+ 
+  if (!sPrefsInitialized) {
+    initializeObjectLoadingContentPrefs();
+  }
+
+  if (mContentBlockingEnabled && mURI && IsFlashMIME(mContentType) && sBlockURIs ) {
+    return true;
+  }
+
+  return false;
+}
+
+bool
+nsObjectLoadingContent::ShouldPlay(FallbackType &aReason, bool aIgnoreCurrentType)
+{
+  nsresult rv;
+
+  if (!sPrefsInitialized) {
+    initializeObjectLoadingContentPrefs();
+  }
+
+  if (BrowserTabsRemoteAutostart()) {
+    bool shouldLoadInParent = nsPluginHost::ShouldLoadTypeInParent(mContentType);
+    bool inParent = XRE_IsParentProcess();
+
+    if (shouldLoadInParent != inParent) {
+      // Plugins need to be locked to either the parent process or the content
+      // process. If a plugin is locked to one process type, it can't be used in
+      // the other. Otherwise we'll get hangs.
+      aReason = eFallbackDisabled;
+      return false;
+    }
+  }
+
+  RefPtr<nsPluginHost> pluginHost = nsPluginHost::GetInst();
+
+  // at this point if it's not a plugin, we let it play/fallback
+  if (!aIgnoreCurrentType && mType != eType_Plugin) {
+    return true;
+  }
+
+  // Order of checks:
+  // * Assume a default of click-to-play
+  // * If globally disabled, per-site permissions cannot override.
+  // * If blocklisted, override the reason with the blocklist reason
+  // * Check per-site permissions and follow those if specified.
+  // * Honor per-plugin disabled permission
+  // * Blocklisted plugins are forced to CtP
+  // * Check per-plugin permission and follow that.
+
+  aReason = eFallbackClickToPlay;
+
+  uint32_t enabledState = nsIPluginTag::STATE_DISABLED;
+  pluginHost->GetStateForType(mContentType, nsPluginHost::eExcludeNone,
+                              &enabledState);
+  if (nsIPluginTag::STATE_DISABLED == enabledState) {
+    aReason = eFallbackDisabled;
+    return false;
+  }
+
+  // Before we check permissions, get the blocklist state of this plugin to set
+  // the fallback reason correctly. In the content process this will involve
+  // an ipc call to chrome.
+  uint32_t blocklistState = nsIBlocklistService::STATE_BLOCKED;
+  pluginHost->GetBlocklistStateForType(mContentType,
+                                       nsPluginHost::eExcludeNone,
+                                       &blocklistState);
+  if (blocklistState == nsIBlocklistService::STATE_BLOCKED) {
+    // no override possible
+    aReason = eFallbackBlocklisted;
+    return false;
+  }
+
+  if (blocklistState == nsIBlocklistService::STATE_VULNERABLE_UPDATE_AVAILABLE) {
+    aReason = eFallbackVulnerableUpdatable;
+  }
+  else if (blocklistState == nsIBlocklistService::STATE_VULNERABLE_NO_UPDATE) {
+    aReason = eFallbackVulnerableNoUpdate;
+  }
+
+  // Check the permission manager for permission based on the principal of
+  // the toplevel content.
+
+  nsCOMPtr<nsIContent> thisContent = do_QueryInterface(static_cast<nsIObjectLoadingContent*>(this));
+  MOZ_ASSERT(thisContent);
+  nsIDocument* ownerDoc = thisContent->OwnerDoc();
+
+  nsCOMPtr<nsPIDOMWindowOuter> window = ownerDoc->GetWindow();
+  if (!window) {
+    return false;
+  }
+  nsCOMPtr<nsPIDOMWindowOuter> topWindow = window->GetTop();
+  NS_ENSURE_TRUE(topWindow, false);
+  nsCOMPtr<nsIDocument> topDoc = topWindow->GetDoc();
+  NS_ENSURE_TRUE(topDoc, false);
+
+  nsCOMPtr<nsIPermissionManager> permissionManager = services::GetPermissionManager();
+  NS_ENSURE_TRUE(permissionManager, false);
+
+  // For now we always say that the system principal uses click-to-play since
+  // that maintains current behavior and we have tests that expect this.
+  // What we really should do is disable plugins entirely in pages that use
+  // the system principal, i.e. in chrome pages. That way the click-to-play
+  // code here wouldn't matter at all. Bug 775301 is tracking this.
+  if (!nsContentUtils::IsSystemPrincipal(topDoc->NodePrincipal())) {
+    nsAutoCString permissionString;
+    rv = pluginHost->GetPermissionStringForType(mContentType,
+                                                nsPluginHost::eExcludeNone,
+                                                permissionString);
+    NS_ENSURE_SUCCESS(rv, false);
+    uint32_t permission;
+    rv = permissionManager->TestPermissionFromPrincipal(topDoc->NodePrincipal(),
+                                                        permissionString.Data(),
+                                                        &permission);
+    NS_ENSURE_SUCCESS(rv, false);
+    if (permission != nsIPermissionManager::UNKNOWN_ACTION) {
+      uint64_t nowms = PR_Now() / 1000;
+      permissionManager->UpdateExpireTime(
+        topDoc->NodePrincipal(), permissionString.Data(), false,
+        nowms + sSessionTimeoutMinutes * 60 * 1000,
+        nowms / 1000 + uint64_t(sPersistentTimeoutDays) * 24 * 60 * 60 * 1000);
+    }
+    switch (permission) {
+    case nsIPermissionManager::ALLOW_ACTION:
+      if (PreferFallback(false /* isPluginClickToPlay */)) {
+        aReason = eFallbackAlternate;
+        return false;
+      }
+
+      return true;
+    case nsIPermissionManager::DENY_ACTION:
+      aReason = eFallbackDisabled;
+      return false;
+    case nsIPermissionManager::PROMPT_ACTION:
+      if (PreferFallback(true /* isPluginClickToPlay */)) {
+        // False is already returned in this case, but
+        // it's important to correctly set aReason too.
+        aReason = eFallbackAlternate;
+      }
+
+      return false;
+    case nsIPermissionManager::UNKNOWN_ACTION:
+      break;
+    default:
+      MOZ_ASSERT(false);
+      return false;
+    }
+  }
+
+  // No site-specific permissions. Vulnerable plugins are automatically CtP
+  if (blocklistState == nsIBlocklistService::STATE_VULNERABLE_UPDATE_AVAILABLE ||
+      blocklistState == nsIBlocklistService::STATE_VULNERABLE_NO_UPDATE) {
+    return false;
+  }
+
+  if (PreferFallback(enabledState == nsIPluginTag::STATE_CLICKTOPLAY)) {
+    aReason = eFallbackAlternate;
+    return false;
+  }
+
+  switch (enabledState) {
+  case nsIPluginTag::STATE_ENABLED:
+    return true;
+  case nsIPluginTag::STATE_CLICKTOPLAY:
+    return false;
+  }
+  MOZ_CRASH("Unexpected enabledState");
+}
+
+bool
+nsObjectLoadingContent::FavorFallbackMode(bool aIsPluginClickToPlay) {
+  if (!IsFlashMIME(mContentType)) {
+    return false;
+  }
+
+  nsCString prefString;
+  if (NS_SUCCEEDED(Preferences::GetCString(kPrefFavorFallbackMode, &prefString))) {
+    if (aIsPluginClickToPlay &&
+        prefString.EqualsLiteral("follow-ctp")) {
+      return true;
+    }
+
+    if (prefString.EqualsLiteral("always")) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+nsObjectLoadingContent::HasGoodFallback() {
+  nsCOMPtr<nsIContent> thisContent =
+  do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  NS_ASSERTION(thisContent, "must be a content");
+
+  if (!thisContent->IsHTMLElement(nsGkAtoms::object) ||
+      mContentType.IsEmpty()) {
+    return false;
+  }
+
+  nsTArray<nsCString> rulesList;
+  nsCString prefString;
+  if (NS_SUCCEEDED(Preferences::GetCString(kPrefFavorFallbackRules, &prefString))) {
+      ParseString(prefString, ',', rulesList);
+  }
+
+  for (uint32_t i = 0; i < rulesList.Length(); ++i) {
+    // RULE "embed":
+    // Don't use fallback content if the object contains an <embed> inside its
+    // fallback content.
+    if (rulesList[i].EqualsLiteral("embed")) {
+      nsTArray<nsINodeList*> childNodes;
+      for (nsIContent* child = thisContent->GetFirstChild();
+           child;
+           child = child->GetNextNode(thisContent)) {
+        if (child->IsHTMLElement(nsGkAtoms::embed)) {
+          return false;
+        }
+      }
+    }
+
+    // RULE "video":
+    // Use fallback content if the object contains a <video> inside its
+    // fallback content.
+    if (rulesList[i].EqualsLiteral("video")) {
+      nsTArray<nsINodeList*> childNodes;
+      for (nsIContent* child = thisContent->GetFirstChild();
+           child;
+           child = child->GetNextNode(thisContent)) {
+        if (child->IsHTMLElement(nsGkAtoms::video)) {
+          return true;
+        }
+      }
+    }
+
+    // RULE "adobelink":
+    // Don't use fallback content when it has a link to adobe's website.
+    if (rulesList[i].EqualsLiteral("adobelink")) {
+      nsTArray<nsINodeList*> childNodes;
+      for (nsIContent* child = thisContent->GetFirstChild();
+           child;
+           child = child->GetNextNode(thisContent)) {
+        if (child->IsHTMLElement(nsGkAtoms::a)) {
+          nsCOMPtr<nsIURI> href = child->GetHrefURI();
+          if (href) {
+            nsAutoCString asciiHost;
+            nsresult rv = href->GetAsciiHost(asciiHost);
+            if (NS_SUCCEEDED(rv) &&
+                !asciiHost.IsEmpty() &&
+                (asciiHost.EqualsLiteral("adobe.com") ||
+                 StringEndsWith(asciiHost, NS_LITERAL_CSTRING(".adobe.com")))) {
+              return false;
+            }
+          }
+        }
+      }
+    }
+
+    // RULE "installinstructions":
+    // Don't use fallback content when the text content on the fallback appears
+    // to contain instructions to install or download Flash.
+    if (rulesList[i].EqualsLiteral("installinstructions")) {
+      nsAutoString textContent;
+      ErrorResult rv;
+      thisContent->GetTextContent(textContent, rv);
+      bool hasText =
+        !rv.Failed() &&
+        (CaseInsensitiveFindInReadable(NS_LITERAL_STRING("Flash"), textContent) ||
+         CaseInsensitiveFindInReadable(NS_LITERAL_STRING("Install"), textContent) ||
+         CaseInsensitiveFindInReadable(NS_LITERAL_STRING("Download"), textContent));
+
+      if (hasText) {
+        return false;
+      }
+    }
+
+    // RULE "true":
+    // By having a rule that returns true, we can put it at the end of the rules list
+    // to change the default-to-false behavior to be default-to-true.
+    if (rulesList[i].EqualsLiteral("true")) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+nsObjectLoadingContent::PreferFallback(bool aIsPluginClickToPlay) {
+  if (mPreferFallbackKnown) {
+    return mPreferFallback;
+  }
+
+  mPreferFallbackKnown = true;
+  mPreferFallback = FavorFallbackMode(aIsPluginClickToPlay) && HasGoodFallback();
+  return mPreferFallback;
+}
+
+nsIDocument*
+nsObjectLoadingContent::GetContentDocument(nsIPrincipal& aSubjectPrincipal)
+{
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+
+  if (!thisContent->IsInComposedDoc()) {
+    return nullptr;
+  }
+
+  nsIDocument *sub_doc = thisContent->OwnerDoc()->GetSubDocumentFor(thisContent);
+  if (!sub_doc) {
+    return nullptr;
+  }
+
+  // Return null for cross-origin contentDocument.
+  if (!aSubjectPrincipal.SubsumesConsideringDomain(sub_doc->NodePrincipal())) {
+    return nullptr;
+  }
+
+  return sub_doc;
+}
+
+void
+nsObjectLoadingContent::LegacyCall(JSContext* aCx,
+                                   JS::Handle<JS::Value> aThisVal,
+                                   const Sequence<JS::Value>& aArguments,
+                                   JS::MutableHandle<JS::Value> aRetval,
+                                   ErrorResult& aRv)
+{
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  JS::Rooted<JSObject*> obj(aCx, thisContent->GetWrapper());
+  MOZ_ASSERT(obj, "How did we get called?");
+
+  // Make sure we're not dealing with an Xray.  Our DoCall code can't handle
+  // random cross-compartment wrappers, so we're going to have to wrap
+  // everything up into our compartment, but that means we need to check that
+  // this is not an Xray situation by hand.
+  if (!JS_WrapObject(aCx, &obj)) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return;
+  }
+
+  if (nsDOMClassInfo::ObjectIsNativeWrapper(aCx, obj)) {
+    aRv.Throw(NS_ERROR_NOT_AVAILABLE);
+    return;
+  }
+
+  obj = thisContent->GetWrapper();
+  // Now wrap things up into the compartment of "obj"
+  JSAutoCompartment ac(aCx, obj);
+  JS::AutoValueVector args(aCx);
+  if (!args.append(aArguments.Elements(), aArguments.Length())) {
+    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+    return;
+  }
+
+  for (size_t i = 0; i < args.length(); i++) {
+    if (!JS_WrapValue(aCx, args[i])) {
+      aRv.Throw(NS_ERROR_UNEXPECTED);
+      return;
+    }
+  }
+
+  JS::Rooted<JS::Value> thisVal(aCx, aThisVal);
+  if (!JS_WrapValue(aCx, &thisVal)) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return;
+  }
+
+  RefPtr<nsNPAPIPluginInstance> pi;
+  nsresult rv = ScriptRequestPluginInstance(aCx, getter_AddRefs(pi));
+  if (NS_FAILED(rv)) {
+    aRv.Throw(rv);
+    return;
+  }
+
+  // if there's no plugin around for this object, throw.
+  if (!pi) {
+    aRv.Throw(NS_ERROR_NOT_AVAILABLE);
+    return;
+  }
+
+  JS::Rooted<JSObject*> pi_obj(aCx);
+  JS::Rooted<JSObject*> pi_proto(aCx);
+
+  rv = GetPluginJSObject(aCx, obj, pi, &pi_obj, &pi_proto);
+  if (NS_FAILED(rv)) {
+    aRv.Throw(rv);
+    return;
+  }
+
+  if (!pi_obj) {
+    aRv.Throw(NS_ERROR_NOT_AVAILABLE);
+    return;
+  }
+
+  bool ok = JS::Call(aCx, thisVal, pi_obj, args, aRetval);
+  if (!ok) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return;
+  }
+
+  Telemetry::Accumulate(Telemetry::PLUGIN_CALLED_DIRECTLY, true);
+}
+
+void
+nsObjectLoadingContent::SetupProtoChain(JSContext* aCx,
+                                        JS::Handle<JSObject*> aObject)
+{
+  if (mType != eType_Plugin) {
+    return;
+  }
+
+  if (!nsContentUtils::IsSafeToRunScript()) {
+    RefPtr<SetupProtoChainRunner> runner = new SetupProtoChainRunner(this);
+    nsContentUtils::AddScriptRunner(runner);
+    return;
+  }
+
+  // We get called on random compartments here for some reason
+  // (perhaps because WrapObject can happen on a random compartment?)
+  // so make sure to enter the compartment of aObject.
+  MOZ_ASSERT(aCx == nsContentUtils::GetCurrentJSContext());
+
+  JSAutoCompartment ac(aCx, aObject);
+
+  RefPtr<nsNPAPIPluginInstance> pi;
+  nsresult rv = ScriptRequestPluginInstance(aCx, getter_AddRefs(pi));
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  if (!pi) {
+    // No plugin around for this object.
+    return;
+  }
+
+  JS::Rooted<JSObject*> pi_obj(aCx); // XPConnect-wrapped peer object, when we get it.
+  JS::Rooted<JSObject*> pi_proto(aCx); // 'pi.__proto__'
+
+  rv = GetPluginJSObject(aCx, aObject, pi, &pi_obj, &pi_proto);
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  if (!pi_obj) {
+    // Didn't get a plugin instance JSObject, nothing we can do then.
+    return;
+  }
+
+  // If we got an xpconnect-wrapped plugin object, set obj's
+  // prototype's prototype to the scriptable plugin.
+
+  JS::Handle<JSObject*> my_proto = GetDOMClass(aObject)->mGetProto(aCx);
+  MOZ_ASSERT(my_proto);
+
+  // Set 'this.__proto__' to pi
+  if (!::JS_SetPrototype(aCx, aObject, pi_obj)) {
+    return;
+  }
+
+  if (pi_proto && js::GetObjectClass(pi_proto) != js::ObjectClassPtr) {
+    // The plugin wrapper has a proto that's not Object.prototype, set
+    // 'pi.__proto__.__proto__' to the original 'this.__proto__'
+    if (pi_proto != my_proto && !::JS_SetPrototype(aCx, pi_proto, my_proto)) {
+      return;
+    }
+  } else {
+    // 'pi' didn't have a prototype, or pi's proto was
+    // 'Object.prototype' (i.e. pi is an NPRuntime wrapped JS object)
+    // set 'pi.__proto__' to the original 'this.__proto__'
+    if (!::JS_SetPrototype(aCx, pi_obj, my_proto)) {
+      return;
+    }
+  }
+
+  // Before this proto dance the objects involved looked like this:
+  //
+  // this.__proto__.__proto__
+  //   ^      ^         ^
+  //   |      |         |__ Object.prototype
+  //   |      |
+  //   |      |__ WebIDL prototype (shared)
+  //   |
+  //   |__ WebIDL object
+  //
+  // pi.__proto__
+  // ^      ^
+  // |      |__ Object.prototype or some other object
+  // |
+  // |__ Plugin NPRuntime JS object wrapper
+  //
+  // Now, after the above prototype setup the prototype chain should
+  // look like this if pi.__proto__ was Object.prototype:
+  //
+  // this.__proto__.__proto__.__proto__
+  //   ^      ^         ^         ^
+  //   |      |         |         |__ Object.prototype
+  //   |      |         |
+  //   |      |         |__ WebIDL prototype (shared)
+  //   |      |
+  //   |      |__ Plugin NPRuntime JS object wrapper
+  //   |
+  //   |__ WebIDL object
+  //
+  // or like this if pi.__proto__ was some other object:
+  //
+  // this.__proto__.__proto__.__proto__.__proto__
+  //   ^      ^         ^         ^         ^
+  //   |      |         |         |         |__ Object.prototype
+  //   |      |         |         |
+  //   |      |         |         |__ WebIDL prototype (shared)
+  //   |      |         |
+  //   |      |         |__ old pi.__proto__
+  //   |      |
+  //   |      |__ Plugin NPRuntime JS object wrapper
+  //   |
+  //   |__ WebIDL object
+  //
+}
+
+// static
+nsresult
+nsObjectLoadingContent::GetPluginJSObject(JSContext *cx,
+                                          JS::Handle<JSObject*> obj,
+                                          nsNPAPIPluginInstance *plugin_inst,
+                                          JS::MutableHandle<JSObject*> plugin_obj,
+                                          JS::MutableHandle<JSObject*> plugin_proto)
+{
+  // NB: We need an AutoEnterCompartment because we can be called from
+  // nsPluginFrame when the plugin loads after the JS object for our content
+  // node has been created.
+  JSAutoCompartment ac(cx, obj);
+
+  if (plugin_inst) {
+    plugin_inst->GetJSObject(cx, plugin_obj.address());
+    if (plugin_obj) {
+      if (!::JS_GetPrototype(cx, plugin_obj, plugin_proto)) {
+        return NS_ERROR_UNEXPECTED;
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+void
+nsObjectLoadingContent::TeardownProtoChain()
+{
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+
+  NS_ENSURE_TRUE_VOID(thisContent->GetWrapper());
+
+  // We don't init the AutoJSAPI with our wrapper because we don't want it
+  // reporting errors to our window's onerror listeners.
+  AutoJSAPI jsapi;
+  jsapi.Init();
+  JSContext* cx = jsapi.cx();
+  JS::Rooted<JSObject*> obj(cx, thisContent->GetWrapper());
+  MOZ_ASSERT(obj);
+
+  JS::Rooted<JSObject*> proto(cx);
+  JSAutoCompartment ac(cx, obj);
+
+  // Loop over the DOM element's JS object prototype chain and remove
+  // all JS objects of the class sNPObjectJSWrapperClass
+  DebugOnly<bool> removed = false;
+  while (obj) {
+    if (!::JS_GetPrototype(cx, obj, &proto)) {
+      return;
+    }
+    if (!proto) {
+      break;
+    }
+    // Unwrap while checking the class - if the prototype is a wrapper for
+    // an NP object, that counts too.
+    if (nsNPObjWrapper::IsWrapper(js::UncheckedUnwrap(proto))) {
+      // We found an NPObject on the proto chain, get its prototype...
+      if (!::JS_GetPrototype(cx, proto, &proto)) {
+        return;
+      }
+
+      MOZ_ASSERT(!removed, "more than one NPObject in prototype chain");
+      removed = true;
+
+      // ... and pull it out of the chain.
+      ::JS_SetPrototype(cx, obj, proto);
+    }
+
+    obj = proto;
+  }
+}
+
+bool
+nsObjectLoadingContent::DoResolve(JSContext* aCx, JS::Handle<JSObject*> aObject,
+                                  JS::Handle<jsid> aId,
+                                  JS::MutableHandle<JS::PropertyDescriptor> aDesc)
+{
+  // We don't resolve anything; we just try to make sure we're instantiated.
+  // This purposefully does not fire for chrome/xray resolves, see bug 967694
+
+  RefPtr<nsNPAPIPluginInstance> pi;
+  nsresult rv = ScriptRequestPluginInstance(aCx, getter_AddRefs(pi));
+  if (NS_FAILED(rv)) {
+    return mozilla::dom::Throw(aCx, rv);
+  }
+  return true;
+}
+
+/* static */
+bool
+nsObjectLoadingContent::MayResolve(jsid aId)
+{
+  // We can resolve anything, really.
+  return true;
+}
+
+void
+nsObjectLoadingContent::GetOwnPropertyNames(JSContext* aCx,
+                                            nsTArray<nsString>& /* unused */,
+                                            ErrorResult& aRv)
+{
+  // Just like DoResolve, just make sure we're instantiated.  That will do
+  // the work our Enumerate hook needs to do.  This purposefully does not fire
+  // for xray resolves, see bug 967694
+  RefPtr<nsNPAPIPluginInstance> pi;
+  aRv = ScriptRequestPluginInstance(aCx, getter_AddRefs(pi));
+}
+
+void
+nsObjectLoadingContent::MaybeFireErrorEvent()
+{
+  nsCOMPtr<nsIContent> thisContent =
+    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
+  // Queue a task to fire an error event if we're an <object> element.  The
+  // queueing is important, since then we don't have to worry about reentry.
+  if (thisContent->IsHTMLElement(nsGkAtoms::object)) {
+    RefPtr<AsyncEventDispatcher> loadBlockingAsyncDispatcher =
+      new LoadBlockingAsyncEventDispatcher(thisContent,
+                                           NS_LITERAL_STRING("error"),
+                                           false, false);
+    loadBlockingAsyncDispatcher->PostDOMEvent();
+  }
+}
+
+// SetupProtoChainRunner implementation
+nsObjectLoadingContent::SetupProtoChainRunner::SetupProtoChainRunner(
+    nsObjectLoadingContent* aContent)
+  : mContent(aContent)
+{
+}
+
+nsObjectLoadingContent::SetupProtoChainRunner::~SetupProtoChainRunner()
+{
+}
+
+NS_IMETHODIMP
+nsObjectLoadingContent::SetupProtoChainRunner::Run()
+{
+  AutoJSAPI jsapi;
+  jsapi.Init();
+  JSContext* cx = jsapi.cx();
+
+  nsCOMPtr<nsIContent> content;
+  CallQueryInterface(mContent.get(), getter_AddRefs(content));
+  JS::Rooted<JSObject*> obj(cx, content->GetWrapper());
+  if (!obj) {
+    // No need to set up our proto chain if we don't even have an object
+    return NS_OK;
+  }
+  nsObjectLoadingContent* objectLoadingContent =
+    static_cast<nsObjectLoadingContent*>(mContent.get());
+  objectLoadingContent->SetupProtoChain(cx, obj);
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(nsObjectLoadingContent::SetupProtoChainRunner, nsIRunnable)