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

media/renderers/audio_renderer_impl.h

 // Copyright (c) 2012 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.
 
 // Audio rendering unit utilizing an AudioRendererSink to output data.
 //
 // This class lives inside three threads during it's lifetime, namely:
 // 1. Render thread
 //    Where the object is created.
 // 2. Media thread (provided via constructor)
@@ skipping 276 matching lines @@
   base::TimeTicks stop_rendering_time_;
 
   // Set upon receipt of the first decoded buffer after a StartPlayingFrom().
   // Used to determine how long to delay playback.
   base::TimeDelta first_packet_timestamp_;
 
   // Set by OnSuspend() and OnResume() to indicate when the system is about to
   // suspend/is suspended and when it resumes.
   bool is_suspending_;
 
+  // Indicates if we've rendered the first valid frame after SetMediaTime().
+  bool rendered_first_frame_;
+
   // End variables which must be accessed under |lock_|. ----------------------
 
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<AudioRendererImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_RENDERERS_AUDIO_RENDERER_IMPL_H_