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..cacb84d2301b9c8760923a16ce2a718f0029e68c
--- /dev/null
+++ b/content/public/renderer/media_stream_audio_sink.h
@@ -0,0 +1,51 @@
+// 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 CONTENT_EXPORT MediaStreamAudioSink {
+ public:
+  // 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|.
+  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 calling OnData().
+  virtual void OnSetFormat(const media::AudioParameters& params) = 0;
+
+ protected:
+  virtual ~MediaStreamAudioSink() {}
+};
+
+CONTENT_EXPORT void AddToAudioTrack(
+    MediaStreamAudioSink* sink, const blink::WebMediaStreamTrack& track);
+
+CONTENT_EXPORT void RemoveFromAudioTrack(
+    MediaStreamAudioSink* sink, const blink::WebMediaStreamTrack& track);
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_AUDIO_SINK_H_