[Media] Record time it takes to start rendering audio and video

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 07ea2241cfb145ede0b0a233e3adc779bdcf1a23..f3eb0d622c15c626cf27629a02d5e334bfcbb198 100644
--- a/media/renderers/renderer_impl.h
+++ b/media/renderers/renderer_impl.h
@@ -145,6 +145,7 @@ class MEDIA_EXPORT RendererImpl : public Renderer {
   void OnWaitingForDecryptionKey();
   void OnVideoNaturalSizeChange(const gfx::Size& size);
   void OnVideoOpacityChange(bool opaque);
+  void OnFirstFrameRender(DemuxerStream::Type type);
 
   State state_;
 
@@ -195,6 +196,12 @@ class MEDIA_EXPORT RendererImpl : public Renderer {
   // runs out of data but the audio renderer still has enough.
   base::TimeDelta video_underflow_threshold_;
 
+  // Timestamps when the playback is initiated after play or seek that's set at
+  // StartPlayingFrom(). Used to calculate and report the preroll time from
+  // StartPlayingFrom() to HAVE_ENOUGH_DATA.
+  base::TimeTicks audio_preroll_start_time_;
+  base::TimeTicks video_preroll_start_time_;
+
   bool restarting_audio_ = false;
   bool restarting_video_ = false;