Bug 998284. When entering the buffering state from AdvanceFrame, be prepared to accept a second's delay before reevaluating whether to exit buffering. r=cpearce

--HG--
extra : rebase_source : 2a7aab19c998f6977cb47d6300e2967be69bcbdf

content/media/MediaDecoderStateMachine.cpp

@@ -2466,7 +2466,10 @@ void MediaDecoderStateMachine::AdvanceFrame()
         mReader->VideoQueue().PushFront(currentFrame.forget());
       }
       StartBuffering();
-      ScheduleStateMachine();
+      // Don't go straight back to the state machine loop since that might
+      // cause us to start decoding again and we could flip-flop between
+      // decoding and quick-buffering.
+      ScheduleStateMachine(USECS_PER_S);
       return;
     }
   }