Allow media track switching.

media/renderers/renderer_impl.h

Index: media/renderers/renderer_impl.h
diff --git a/media/renderers/renderer_impl.h b/media/renderers/renderer_impl.h
index f55a7635e22707644c5b818813542d23a49544c0..f0264b9a73e1d0aac32aada240b4958640334f06 100644
--- a/media/renderers/renderer_impl.h
+++ b/media/renderers/renderer_impl.h
@@ -106,8 +106,14 @@ class MEDIA_EXPORT RendererImpl : public Renderer {
   void FlushVideoRenderer();
   void OnVideoRendererFlushDone();
 
-  void RestartAudioRenderer(base::TimeDelta time);
-  void RestartVideoRenderer(base::TimeDelta time);
+  void RestartAudioRenderer(DemuxerStream* stream, base::TimeDelta time);

[xhwang, 2017/03/22 22:31:12]

Please add a comment about what the |stream| is, and what the |time| is for.

[servolk, 2017/03/23 17:08:10]

Done.

+  void OnAudioRendererReinitCompleted(DemuxerStream* stream,
+                                      base::TimeDelta time,
+                                      PipelineStatus status);

[xhwang, 2017/03/22 22:31:12]

naming nit: Are "Restart" and "Reinit" the same thing? Let's pick one an be
consistent.

[servolk, 2017/03/23 17:08:10]

No restart and reinit are different things. Reinit completely reinitializes the
renderer with a different DemuxerStream, which includes re-creating audio
decoders and re-running the decoder selection. Whereas restart simply restarts
the playback in audio renderer, for example after the media track has been
disabled and became re-enabled. I've made the comments above more detailed to
explain this.

+  void RestartVideoRenderer(DemuxerStream* stream, base::TimeDelta time);
+  void OnVideoRendererReinitCompleted(DemuxerStream* stream,
+                                      base::TimeDelta time,
+                                      PipelineStatus status);
 
   // Callback executed by filters to update statistics.
   void OnStatisticsUpdate(const PipelineStatistics& stats);
@@ -166,6 +172,9 @@ class MEDIA_EXPORT RendererImpl : public Renderer {
   std::unique_ptr<AudioRenderer> audio_renderer_;
   std::unique_ptr<VideoRenderer> video_renderer_;
 
+  DemuxerStream* current_audio_stream_;
+  DemuxerStream* current_video_stream_;
+
   // Renderer-provided time source used to control playback.
   TimeSource* time_source_;
   std::unique_ptr<WallClockTimeSource> wall_clock_time_source_;