Bug 1179116. Part 1 - clean up code of MediaDecoderStateMachine::MaybeStartPlayback(). r=cpearce.

dom/media/MediaDecoderStateMachine.cpp

@@ -1284,17 +1284,19 @@ void MediaDecoderStateMachine::MaybeStartPlayback()
 {
   MOZ_ASSERT(OnTaskQueue());
   AssertCurrentThreadInMonitor();
+  MOZ_ASSERT(mState == DECODER_STATE_DECODING ||
+             mState == DECODER_STATE_COMPLETED);
+
   if (IsPlaying()) {
     // Logging this case is really spammy - don't do it.
     return;
   }
 
   bool playStatePermits = mPlayState == MediaDecoder::PLAY_STATE_PLAYING;
-  bool decodeStatePermits = mState == DECODER_STATE_DECODING || mState == DECODER_STATE_COMPLETED;
-  if (!playStatePermits || !decodeStatePermits || mIsAudioPrerolling || mIsVideoPrerolling) {
-    DECODER_LOG("Not starting playback [playStatePermits: %d, decodeStatePermits: %d, "
-                "mIsAudioPrerolling: %d, mIsVideoPrerolling: %d]", (int) playStatePermits,
-                (int) decodeStatePermits, (int) mIsAudioPrerolling, (int) mIsVideoPrerolling);
+  if (!playStatePermits || mIsAudioPrerolling || mIsVideoPrerolling) {
+    DECODER_LOG("Not starting playback [playStatePermits: %d, "
+                "mIsAudioPrerolling: %d, mIsVideoPrerolling: %d]",
+                (int) playStatePermits, (int) mIsAudioPrerolling, (int) mIsVideoPrerolling);
     return;
   }
 
@@ -2605,7 +2607,6 @@ nsresult MediaDecoderStateMachine::RunStateMachine()
 
       // Notify to allow blocked decoder thread to continue
       mDecoder->GetReentrantMonitor().NotifyAll();
-      MaybeStartPlayback();
       NS_ASSERTION(IsStateMachineScheduled(), "Must have timer scheduled");
       return NS_OK;
     }