Bug 882027. Make MediaDecoder::UpdateReadyStateForData always be responsible for calling GetNextFrameStatus when that value is passed to HTMLMediaElement::UpdateReadyStateForData, but keep calling GetNextFrameStatus on the state machine thread to suppress dispatching of redundant runnables when nothing has changed. r=cpearce

content/media/MediaDecoder.cpp

@@ -1046,32 +1046,6 @@ void MediaDecoder::NotifyBytesConsumed(int64_t aBytes)
   }
 }
 
-void MediaDecoder::NextFrameUnavailableBuffering()
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  if (!mOwner || mShuttingDown || !mDecoderStateMachine)
-    return;
-
-  mOwner->UpdateReadyStateForData(MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE_BUFFERING);
-}
-
-void MediaDecoder::NextFrameAvailable()
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  if (!mOwner || mShuttingDown || !mDecoderStateMachine)
-    return;
-
-  mOwner->UpdateReadyStateForData(MediaDecoderOwner::NEXT_FRAME_AVAILABLE);
-}
-
-void MediaDecoder::NextFrameUnavailable()
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  if (!mOwner || mShuttingDown || !mDecoderStateMachine)
-    return;
-  mOwner->UpdateReadyStateForData(MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE);
-}
-
 void MediaDecoder::UpdateReadyStateForData()
 {
   MOZ_ASSERT(NS_IsMainThread());

content/media/MediaDecoder.h

@@ -710,12 +710,6 @@ public:
   // This must be called on the main thread only.
   void PlaybackPositionChanged();
 
-  // Calls mElement->UpdateReadyStateForData, telling it which state we have
-  // entered.  Main thread only.
-  void NextFrameUnavailableBuffering();
-  void NextFrameAvailable();
-  void NextFrameUnavailable();
-
   // Calls mElement->UpdateReadyStateForData, telling it whether we have
   // data for the next frame and if we're buffering. Main thread only.
   void UpdateReadyStateForData();

content/media/MediaDecoderStateMachine.cpp

@@ -2620,21 +2620,16 @@ void MediaDecoderStateMachine::UpdateReadyState() {
   }
   mLastFrameStatus = nextFrameStatus;
 
+  /* This is a bit tricky. MediaDecoder::UpdateReadyStateForData will run on
+   * the main thread and re-evaluate GetNextFrameStatus there, passing it to
+   * HTMLMediaElement::UpdateReadyStateForData. It doesn't use the value of
+   * GetNextFrameStatus we computed here, because what we're computing here
+   * could be stale by the time MediaDecoder::UpdateReadyStateForData runs.
+   * We only compute GetNextFrameStatus here to avoid posting runnables to the main
+   * thread unnecessarily.
+   */
   nsCOMPtr<nsIRunnable> event;
-  switch (nextFrameStatus) {
-    case MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE_BUFFERING:
-      event = NS_NewRunnableMethod(mDecoder, &MediaDecoder::NextFrameUnavailableBuffering);
-      break;
-    case MediaDecoderOwner::NEXT_FRAME_AVAILABLE:
-      event = NS_NewRunnableMethod(mDecoder, &MediaDecoder::NextFrameAvailable);
-      break;
-    case MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE:
-      event = NS_NewRunnableMethod(mDecoder, &MediaDecoder::NextFrameUnavailable);
-      break;
-    default:
-      PR_NOT_REACHED("unhandled frame state");
-  }
-
+  event = NS_NewRunnableMethod(mDecoder, &MediaDecoder::UpdateReadyStateForData);
   NS_DispatchToMainThread(event, NS_DISPATCH_NORMAL);
 }