Freeze media time and audio rendering when the system suspends.

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)
 //    All AudioDecoder methods are called on this thread.
 // 3. Audio thread created by the AudioRendererSink.
 //    Render() is called here where audio data is decoded into raw PCM data.
 //
 // AudioRendererImpl talks to an AudioRendererAlgorithm that takes care of
 // queueing audio data and stretching/shrinking audio data when playback rate !=
 // 1.0 or 0.0.
 
 #ifndef MEDIA_RENDERERS_AUDIO_RENDERER_IMPL_H_
 #define MEDIA_RENDERERS_AUDIO_RENDERER_IMPL_H_
 
 #include <stdint.h>
 
 #include <deque>
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/power_monitor/power_observer.h"
 #include "base/synchronization/lock.h"
 #include "media/base/audio_decoder.h"
 #include "media/base/audio_renderer.h"
 #include "media/base/audio_renderer_sink.h"
 #include "media/base/decryptor.h"
 #include "media/base/media_log.h"
 #include "media/base/time_source.h"
 #include "media/filters/audio_renderer_algorithm.h"
 #include "media/filters/decoder_stream.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 class TickClock;
 }
 
 namespace media {
 
 class AudioBufferConverter;
 class AudioBus;
 class AudioClock;
 class AudioHardwareConfig;
 class AudioSplicer;
 class DecryptingDemuxerStream;
 
 class MEDIA_EXPORT AudioRendererImpl
     : public AudioRenderer,
       public TimeSource,
+      public base::PowerObserver,
       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.
   AudioRendererImpl(
       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
       AudioRendererSink* sink,
@@ skipping 14 matching lines @@
   // AudioRenderer implementation.
   void Initialize(DemuxerStream* stream,
                   CdmContext* cdm_context,
                   RendererClient* client,
                   const PipelineStatusCB& init_cb) override;
   TimeSource* GetTimeSource() override;
   void Flush(const base::Closure& callback) override;
   void StartPlaying() override;
   void SetVolume(float volume) override;
 
+  // base::PowerObserver implementation.
+  void OnSuspend() override;
+  void OnResume() override;
+
  private:
   friend class AudioRendererImplTest;
 
   // Important detail: being in kPlaying doesn't imply that audio is being
   // rendered. Rather, it means that the renderer is ready to go. The actual
   // rendering of audio is controlled via Start/StopRendering().
   //
   //   kUninitialized
   //         | Initialize()
   //         |
@@ skipping 178 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 CurrentMediaTime(), used to prevent the current media time value as
   // reported to JavaScript from going backwards in time.
   base::TimeDelta last_media_timestamp_;
 
+  // Set by OnSuspend() and OnResume() to indicate when the system is about to
+  // suspend/is suspended and when it resumes.
+  bool is_suspending_;
+
   // 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_