1 files changed, 6 insertions, 1 deletions
diff --git a/apps/mail/modules/mailMigrator.js b/apps/mail/modules/mailMigrator.js
index 645922227..151735221 100644
--- a/apps/mail/modules/mailMigrator.js
+++ b/apps/mail/modules/mailMigrator.js
@@ -102,7 +102,7 @@ var MailMigrator = {
   _migrateUI: function() {
     // The code for this was ported from
     // mozilla/browser/components/nsBrowserGlue.js
-    const UI_VERSION = 17;
+    const UI_VERSION = 19;
     const MESSENGER_DOCURL = "chrome://messenger/content/messenger.xul";
     const UI_VERSION_PREF = "mail.ui-rdf.version";
     let currentUIVersion = 0;
@@ -413,6 +413,11 @@ var MailMigrator = {
         Services.prefs.clearUserPref("layers.acceleration.force-enabled");
       }
 
+      if (currentUIVersion < 19) {
+        // Clear hardware decoding failure flag to re-test.
+        Services.prefs.clearUserPref("media.hardware-video-decoding.failed");
+      }
+
       // Update the migration version.
       Services.prefs.setIntPref(UI_VERSION_PREF, UI_VERSION);