Add generic interfaces for the sinks of the media stream audio track

content/public/renderer/media_stream_audio_sink.h

Index: content/public/renderer/media_stream_audio_sink.h
diff --git a/content/public/renderer/media_stream_audio_sink.h b/content/public/renderer/media_stream_audio_sink.h
new file mode 100644
index 0000000000000000000000000000000000000000..26ebd54305e468f654cb39adcad0aceb7f08d857
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+++ b/content/public/renderer/media_stream_audio_sink.h
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+// 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 CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_AUDIO_SINK_H_
+#define CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_AUDIO_SINK_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "content/common/content_export.h"
+
+namespace blink {
+class WebMediaStreamTrack;
+}
+
+namespace media {
+class AudioParameters;
+}
+
+namespace content {
+
+class MediaStreamAudioSink {
+ public:
+  // Adds a MediaStreamAudioSink to the audio track to receive audio data from
+  // the track.
+  // Called on the main render thread.
+  static void AddToAudioTrack(MediaStreamAudioSink* sink,
+                              const blink::WebMediaStreamTrack& track);
+
+  // Removes a MediaStreamAudioSink from the audio track to stop receiving
+  // audio data from the track.
+  // Called on the main render thread.
+  static void RemoveFromAudioTrack(MediaStreamAudioSink* sink,
+                                   const blink::WebMediaStreamTrack& track);
+
+  // Callback on delivering the interleaved audio data.
+  // |audio_data| is the pointer to the audio data.
+  // |sample_rate| is the sample frequency of |audio_data|.
+  // |number_of_channels| is the number of audio channels of |audio_data|.
+  // |number_of_frames| is the number of audio frames in the |audio_data|.
+  // Called on real-time audio thread.
+  virtual void OnData(const int16* audio_data,
+                      int sample_rate,
+                      int number_of_channels,
+                      int number_of_frames) = 0;
+
+  // Callback called when the format of the audio stream has changed.
+  // This is called on the same thread as OnData().
+  virtual void OnSetFormat(const media::AudioParameters& params) = 0;
+
+ protected:
+  virtual ~MediaStreamAudioSink() {}
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_AUDIO_SINK_H_