Fix race condition when accessing time_progressing_.

media/renderers/video_renderer_impl.h

Index: media/renderers/video_renderer_impl.h
diff --git a/media/renderers/video_renderer_impl.h b/media/renderers/video_renderer_impl.h
index 7af8bb724f686a3191bfb0fa6a6048e62ad1a8da..6f0884b2d24bab279b2d026deda27e3e1b3e0d11 100644
--- a/media/renderers/video_renderer_impl.h
+++ b/media/renderers/video_renderer_impl.h
@@ -147,8 +147,15 @@ class MEDIA_EXPORT VideoRendererImpl
 
   // Fires |ended_cb_| if there are no remaining usable frames and
   // |received_end_of_stream_| is true.  Sets |rendered_end_of_stream_| if it
-  // does so.  Returns algorithm_->EffectiveFramesQueued().
-  size_t MaybeFireEndedCallback();
+  // does so.
+  //
+  // When called from the media thread, |time_progressing| should reflect the
+  // value of |time_progressing_|.  When called from Render() on the sink
+  // callback thread, the inverse of |render_first_frame_and_stop_| should be
+  // used as a proxy for |time_progressing_|.
+  //
+  // Returns algorithm_->EffectiveFramesQueued().
+  size_t MaybeFireEndedCallback_Locked(bool time_progressing);
 
   // Helper method for converting a single media timestamp to wall clock time.
   base::TimeTicks ConvertMediaTimestamp(base::TimeDelta media_timestamp);
@@ -163,7 +170,8 @@ class MEDIA_EXPORT VideoRendererImpl
   // Sink which calls into VideoRendererImpl via Render() for video frames.  Do
   // not call any methods on the sink while |lock_| is held or the two threads
   // might deadlock. Do not call Start() or Stop() on the sink directly, use
-  // StartSink() and StopSink() to ensure background rendering is started.
+  // StartSink() and StopSink() to ensure background rendering is started.  Only
+  // access these values on |task_runner_|.
   VideoRendererSink* const sink_;
   bool sink_started_;
 
@@ -271,7 +279,8 @@ class MEDIA_EXPORT VideoRendererImpl
   // counted.  Must be accessed under |lock_| once |sink_| is started.
   bool was_background_rendering_;
 
-  // Indicates whether or not media time is currently progressing or not.
+  // Indicates whether or not media time is currently progressing or not.  Must
+  // only be accessed from |task_runner_|.
   bool time_progressing_;
 
   // Indicates that Render() should only render the first frame and then request