Add a silent audio sink to consume WebAudio data on silence detection.

content/renderer/media/renderer_webaudiodevice_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.
 
 #ifndef CONTENT_RENDERER_MEDIA_RENDERER_WEBAUDIODEVICE_IMPL_H_
 #define CONTENT_RENDERER_MEDIA_RENDERER_WEBAUDIODEVICE_IMPL_H_
 
+#include "base/cancelable_callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/thread_checker.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_renderer_sink.h"
 #include "third_party/WebKit/public/platform/WebAudioDevice.h"
 #include "third_party/WebKit/public/platform/WebVector.h"
 
+namespace base {
+class SingleThreadTaskRunner;
+}
+
 namespace media {
 class AudioOutputDevice;
+class NullAudioSink;
 }
 
 namespace content {
 
 class RendererWebAudioDeviceImpl
     : public blink::WebAudioDevice,
       public media::AudioRendererSink::RenderCallback {
  public:
   RendererWebAudioDeviceImpl(const media::AudioParameters& params,
                              blink::WebAudioDevice::RenderCallback* callback,
@@ skipping 19 matching lines @@
   // To avoid the need for locking, ensure the control methods of the
   // blink::WebAudioDevice implementation are called on the same thread.
   base::ThreadChecker thread_checker_;
 
   // When non-NULL, we are started.  When NULL, we are stopped.
   scoped_refptr<media::AudioOutputDevice> output_device_;
 
   // ID to allow browser to select the correct input device for unified IO.
   int session_id_;
 
+  // Timeticks when the silence starts.
+  base::TimeTicks first_silence_time_ ;
+
+  // TaskRunner to post callbacks to the render thread.
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  // A fake audio sink object that consumes data when long period of silence
+  // audio is detected. This object lives on the render thread.
+  scoped_refptr<media::NullAudioSink> null_audio_sink_;
+
+  // Whether audio output is directed to |null_audio_sink_|.
+  bool is_using_null_audio_sink_;
+
+  // First audio buffer after silence finishes. We store this buffer so that
+  // it can be sent to the |output_device_| later after switching from
+  // |null_audio_sink_|.
+  scoped_ptr<media::AudioBus> first_buffer_after_silence_;
+
+  bool is_first_buffer_after_silence_;
+
+  // A cancelable task that is posted to start the |null_audio_sink_| after a
+  // period of silence. We do this on android to save battery consumption.
+  base::CancelableClosure start_null_audio_sink_callback_;
+
   DISALLOW_COPY_AND_ASSIGN(RendererWebAudioDeviceImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_RENDERER_WEBAUDIODEVICE_IMPL_H_