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

content/renderer/media/peer_connection_audio_sink_owner.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_RENDERER_MEDIA_PEER_CONNECTION_AUDIO_SINK_OWNER_H_
+#define CONTENT_RENDERER_MEDIA_PEER_CONNECTION_AUDIO_SINK_OWNER_H_
+
+#include <vector>
+
+#include "base/synchronization/lock.h"
+#include "content/renderer/media/media_stream_audio_track_sink.h"
+
+namespace content {
+
+class PeerConnectionAudioSink;
+
+// Reference counted holder of PeerConnectionAudioSink.
+class PeerConnectionAudioSinkOwner
+    : public MediaStreamAudioTrackSink {
+ public:
+  explicit PeerConnectionAudioSinkOwner(PeerConnectionAudioSink* sink);
+
+  // MediaStreamAudioTrackSink implementation.
+  virtual int OnData(const int16* audio_data,
+                     int sample_rate,
+                     int number_of_channels,
+                     int number_of_frames,
+                     const std::vector<int>& channels,
+                     int audio_delay_milliseconds,
+                     int current_volume,
+                     bool need_audio_processing,
+                     bool key_pressed) OVERRIDE;
+  virtual void OnSetFormat(const media::AudioParameters& params) OVERRIDE;
+  virtual void Reset() OVERRIDE;
+  virtual bool IsEqual(const PeerConnectionAudioSink* other) const OVERRIDE;
+  virtual bool IsEqual(const MediaStreamAudioSink* other) const OVERRIDE{

[tommi (sloooow) - chröme, 2013/11/29 13:00:20]

do you need to override this?

[no longer working on chromium, 2013/11/29 15:02:04]

Yes. For example, when a new MediaStreamAudioSink sink is added to the track, we
loop through all the MediaStreamAudioTrackSink in the lists and check
IsEqual(const MediaStreamAudioSink*), and those PeerConnectionAudioSinkOwner
should just return false in such case.

+    return false;
+  }
+
+ protected:
+  virtual ~PeerConnectionAudioSinkOwner() {}
+
+ private:
+  mutable base::Lock lock_;
+
+  // Weak reference to the delegate, the client need to call Reset() to set the

[tommi (sloooow) - chröme, 2013/11/29 13:00:20]

nit: Raw pointer
s/the client need/the client needs

[no longer working on chromium, 2013/11/29 15:02:04]

Done.

+  // pointer to NULL before the delegate goes away.
+  PeerConnectionAudioSink* delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(PeerConnectionAudioSinkOwner);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_PEER_CONNECTION_AUDIO_SINK_OWNER_H_