Introduce AudioClock to improve playback delay calculations.

media/filters/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 19 matching lines @@
 #include "media/base/decryptor.h"
 #include "media/filters/audio_renderer_algorithm.h"
 #include "media/filters/decoder_stream.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace media {
 
+class AudioBufferConverter;
 class AudioBus;
-class AudioBufferConverter;
+class AudioClock;
+class AudioHardwareConfig;
 class AudioSplicer;
 class DecryptingDemuxerStream;
-class AudioHardwareConfig;
 
 class MEDIA_EXPORT AudioRendererImpl
     : public AudioRenderer,
       NON_EXPORTED_BASE(public AudioRendererSink::RenderCallback) {
  public:
   // |task_runner| is the thread on which AudioRendererImpl will execute.
   //
   // |sink| is used as the destination for the rendered audio.
   //
   // |decoders| contains the AudioDecoders to use when initializing.
@@ skipping 184 matching lines @@
   // Keep track of whether or not the sink is playing.
   bool sink_playing_;
 
   // Keep track of our outstanding read to |decoder_|.
   bool pending_read_;
 
   // Keeps track of whether we received and rendered the end of stream buffer.
   bool received_end_of_stream_;
   bool rendered_end_of_stream_;
 
-  // The timestamp of the last frame (i.e. furthest in the future) buffered as
-  // well as the current time that takes current playback delay into account.
-  base::TimeDelta audio_time_buffered_;
-  base::TimeDelta current_time_;
+  scoped_ptr<AudioClock> audio_clock_;
 
   base::TimeDelta preroll_timestamp_;
 
   // We're supposed to know amount of audio data OS or hardware buffered, but
   // that is not always so -- on my Linux box
   // AudioBuffersState::hardware_delay_bytes never reaches 0.
   //
   // As a result we cannot use it to find when stream ends. If we just ignore
   // buffered data we will notify host that stream ended before it is actually
   // did so, I've seen it done ~140ms too early when playing ~150ms file.
@@ skipping 17 matching lines @@
 
   // 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_FILTERS_AUDIO_RENDERER_IMPL_H_