Bug 1214710 - [3.1] Reset video decode suspend timer when resuming reader. r=jwwang

dom/media/MediaDecoderStateMachine.cpp

@@ -1482,6 +1482,12 @@ void MediaDecoderStateMachine::ReaderSuspendedChanged()
     return;
   }
 
+  if (mIsVisible && mVideoDecodeSuspended) {
+    // The media turned visible while the reader was suspended, reset timer.
+    mVideoDecodeSuspendTimer.Reset();
+    mVideoDecodeSuspended = false;
+  }
+
   InitiateDecodeRecoverySeek(MediaDecoderReader::AUDIO_VIDEO);
 }