Bug 1151656 - Stop doing sync dispatch of PlaybackEnded. r=mattwoodrow

dom/media/MediaDecoderStateMachine.cpp

@@ -243,7 +243,8 @@ MediaDecoderStateMachine::MediaDecoderStateMachine(MediaDecoder* aDecoder,
   mDisabledHardwareAcceleration(false),
   mDecodingFrozenAtStateDecoding(false),
   mSentLoadedMetadataEvent(false),
-  mSentFirstFrameLoadedEvent(false)
+  mSentFirstFrameLoadedEvent(false),
+  mSentPlaybackEndedEvent(false)
 {
   MOZ_COUNT_CTOR(MediaDecoderStateMachine);
   NS_ASSERTION(NS_IsMainThread(), "Should be on main thread.");
@@ -1302,6 +1303,9 @@ void MediaDecoderStateMachine::SetState(State aState)
               gMachineStateStr[mState], gMachineStateStr[aState]);
 
   mState = aState;
+
+  // Clear state-scoped state.
+  mSentPlaybackEndedEvent = false;
 }
 
 void MediaDecoderStateMachine::SetVolume(double volume)
@@ -2702,21 +2706,18 @@ nsresult MediaDecoderStateMachine::RunStateMachine()
 
       StopAudioThread();
 
-      if (mDecoder->GetState() == MediaDecoder::PLAY_STATE_PLAYING) {
+      if (mDecoder->GetState() == MediaDecoder::PLAY_STATE_PLAYING &&
+          !mSentPlaybackEndedEvent)
+      {
         int64_t clockTime = std::max(mAudioEndTime, mVideoFrameEndTime);
         clockTime = std::max(int64_t(0), std::max(clockTime, mEndTime));
         UpdatePlaybackPosition(clockTime);
 
-        {
-          // Wait for the state change is completed in the main thread,
-          // otherwise we might see |mDecoder->GetState() == MediaDecoder::PLAY_STATE_PLAYING|
-          // in next loop and send |MediaDecoder::PlaybackEnded| again to trigger 'ended'
-          // event twice in the media element.
-          ReentrantMonitorAutoExit exitMon(mDecoder->GetReentrantMonitor());
-          nsCOMPtr<nsIRunnable> event =
-            NS_NewRunnableMethod(mDecoder, &MediaDecoder::PlaybackEnded);
-          NS_DispatchToMainThread(event, NS_DISPATCH_SYNC);
-        }
+        nsCOMPtr<nsIRunnable> event =
+          NS_NewRunnableMethod(mDecoder, &MediaDecoder::PlaybackEnded);
+        NS_DispatchToMainThread(event, NS_DISPATCH_NORMAL);
+
+        mSentPlaybackEndedEvent = true;
       }
       return NS_OK;
     }

dom/media/MediaDecoderStateMachine.h

@@ -1237,6 +1237,8 @@ public:
   // to decode any audio/video since the MediaDecoder will trigger a seek
   // operation soon.
   bool mSentFirstFrameLoadedEvent;
+
+  bool mSentPlaybackEndedEvent;
 };
 
 } // namespace mozilla;