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

content/renderer/media/media_stream_audio_sink_owner.cc

+// 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.
+
+#include "content/renderer/media/media_stream_audio_sink_owner.h"
+
+#include "content/public/renderer/media_stream_audio_sink.h"
+#include "media/audio/audio_parameters.h"
+
+namespace content {
+
+MediaStreamAudioSinkOwner::MediaStreamAudioSinkOwner(
+    MediaStreamAudioSink* sink)

[perkj_chrome, 2013/12/03 13:38:53]

nit: argument fits on line above.

[no longer working on chromium, 2013/12/03 13:50:29]

Done.

+    : delegate_(sink) {
+}
+
+int MediaStreamAudioSinkOwner::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) {
+  base::AutoLock lock(lock_);
+  // TODO(xians): Investigate on the possibility of not calling out with the

[perkj_chrome, 2013/12/03 13:38:53]

nit: Investigate the possibility to not grab the lock. 

[no longer working on chromium, 2013/12/03 13:50:29]

I think it is different meaning, we need the lock for atomic operation, and this
TODO is for narrowing the scope of the lock and not calling out.

+  // lock.
+  if (delegate_) {
+    delegate_->OnData(audio_data,
+                      sample_rate,
+                      number_of_channels,
+                      number_of_frames);
+  }
+
+  return 0;
+}
+
+void MediaStreamAudioSinkOwner::OnSetFormat(
+    const media::AudioParameters& params) {
+  base::AutoLock lock(lock_);
+  if (delegate_)
+    delegate_->OnSetFormat(params);
+}
+
+void MediaStreamAudioSinkOwner::Reset() {
+  base::AutoLock lock(lock_);
+  delegate_ = NULL;
+}
+
+bool MediaStreamAudioSinkOwner::IsEqual(
+    const MediaStreamAudioSink* other) const {
+  DCHECK(other);
+  base::AutoLock lock(lock_);
+  return (other == delegate_);
+}
+
+bool MediaStreamAudioSinkOwner::IsEqual(
+    const PeerConnectionAudioSink* other) const {
+  DCHECK(other);
+  return false;
+}
+
+}  // namespace content