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

media/renderers/renderer_impl.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_RENDERERS_RENDERER_IMPL_H_
 #define MEDIA_RENDERERS_RENDERER_IMPL_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 177 matching lines @@
   // Used to defer underflow for video when audio is present.
   base::CancelableClosure deferred_video_underflow_cb_;
 
   // Used to defer underflow for audio when restarting audio playback.
   base::CancelableClosure deferred_audio_restart_underflow_cb_;
 
   // The amount of time to wait before declaring underflow if the video 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;
 
   base::WeakPtr<RendererImpl> weak_this_;
   base::WeakPtrFactory<RendererImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_RENDERERS_RENDERER_IMPL_H_