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

media/renderers/video_renderer_impl.h

 // Copyright 2013 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_VIDEO_RENDERER_IMPL_H_
 #define MEDIA_RENDERERS_VIDEO_RENDERER_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <deque>
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
 #include "base/synchronization/condition_variable.h"
 #include "base/synchronization/lock.h"
+#include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "media/base/decryptor.h"
 #include "media/base/demuxer_stream.h"
 #include "media/base/media_log.h"
 #include "media/base/pipeline_status.h"
 #include "media/base/video_decoder.h"
 #include "media/base/video_frame.h"
 #include "media/base/video_renderer.h"
 #include "media/base/video_renderer_sink.h"
 #include "media/filters/decoder_stream.h"
@@ skipping 252 matching lines @@
   // Indicates if a frame has been processed by CheckForMetadataChanges().
   bool have_renderered_frames_;
 
   // Tracks last frame properties to detect and notify client of any changes.
   gfx::Size last_frame_natural_size_;
   bool last_frame_opaque_;
 
   // Indicates if we've painted the first valid frame after StartPlayingFrom().
   bool painted_first_frame_;
 
+  // The timestamp recorded from |tick_clock_| when the renderer switches from
+  // rendering in the background to rendering in the foreground.
+  // Used to compute how much time it took to paint the first frame.
+  base::TimeTicks shown_timestamp_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<VideoRendererImpl> weak_factory_;
 
   // Weak factory used to invalidate certain queued callbacks on reset().
   // This is useful when doing video frame copies asynchronously since we
   // want to discard video frames that might be received after the stream has
   // been reset.
   base::WeakPtrFactory<VideoRendererImpl> frame_callback_weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoRendererImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_RENDERERS_VIDEO_RENDERER_IMPL_H_