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)
+    : 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_);
+  if (delegate_) {
+    delegate_->OnData(audio_data,

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

what about the return value from delegate_->OnData()?

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

It is a virtual void OnData(const int16* audio_data,
                            int sample_rate,
                            int number_of_channels,
                            int number_of_frames) = 0;

Because no AGC is needed for the new interface, so no return value is needed.

+                      sample_rate,
+                      number_of_channels,
+                      number_of_frames);
+  }
+
+  return 0;
+}
+
+void MediaStreamAudioSinkOwner::OnSetFormat(

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

which methods do we expect to be called from the callback thread and which from
other threads?  Can we add a thread checker for the "main" thread and make it
clear with a comment when we are on the callback thread?

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

OnSetFormat and OnData are called on the same thread, other methods are called
on the main render thread.

As discussed offline, we agreed to not add the thread check for now.

+    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);

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

The reason for having this DCHECK doesn't apply now so IsEqual(NULL) is imho a
valid call to see if the delegate pointer is NULL.

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

why? the caller should make sure other should not be NULL.

+  base::AutoLock lock(lock_);
+  return (other == delegate_);
+}
+
+}  // namespace content