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

content/public/renderer/media_stream_audio_sink.h

+// 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 audio interleaved data.

[Jói, 2013/11/27 17:35:02]

audio interleaved data -> interleaved audio data
(unless "audio interleaved data" is what's commonly used)

[no longer working on chromium, 2013/11/28 17:27:18]

Done.

+  // |audio_data| is the pointer to the audio data.
+  // |sample_rate| is the sample frequency of audio data.

[Jói, 2013/11/27 17:35:02]

audio data -> |audio_data|

[no longer working on chromium, 2013/11/28 17:27:18]

Done.

[no longer working on chromium, 2013/11/28 17:27:18]

Done.

+  // |number_of_channels| is the number of channels reflecting the order of

[Jói, 2013/11/27 17:35:02]

"reflecting the order of surround sound channels" seems a bit vague, what does
it mean?

[no longer working on chromium, 2013/11/28 17:27:18]

OK, I just changed it to is the number of audio channels of |audio_data|. hope
it is more clear.

+  // surround sound channels.
+  // |number_of_frames| is the number of audio frames in the buffer.

[Jói, 2013/11/27 17:35:02]

buffer -> |audio_data|

[no longer working on chromium, 2013/11/28 17:27:18]

Done.

+  virtual void OnData(const int16* audio_data,
+                      int sample_rate,
+                      int number_of_channels,
+                      int number_of_frames) = 0;
+
+  // Callback called when the forma of the audio stream has changed, and

[Jói, 2013/11/27 17:35:02]

forma -> format

Suggest period after "changed" then start a new sentence: This is called on the
same thread as OnData().

[no longer working on chromium, 2013/11/28 17:27:18]

Done.

+  // it will be 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,

[Jói, 2013/11/27 17:35:02]

nit: For consistency with RemoveFromAudioTrack, suggest breaking the line the
same here as is done there.

[no longer working on chromium, 2013/11/28 17:27:18]

Done.

+                                    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_