Add ability to determine if a capture sink is a renderer.

content/renderer/media/webrtc_local_audio_track.cc

Index: content/renderer/media/webrtc_local_audio_track.cc
diff --git a/content/renderer/media/webrtc_local_audio_track.cc b/content/renderer/media/webrtc_local_audio_track.cc
index 37846335e8531270c5c6c66658c400137b82bcf4..832f3ec9d3e2b21a507e549b553dfa8570d7e9be 100644
--- a/content/renderer/media/webrtc_local_audio_track.cc
+++ b/content/renderer/media/webrtc_local_audio_track.cc
@@ -154,13 +154,10 @@ void WebRtcLocalAudioTrack::Capture(media::AudioBus* audio_source,
   int number_of_frames = 0;
   SinkList sinks;
   scoped_refptr<ConfiguredBuffer> current_buffer;
+  bool is_enabled = true;
   {
     base::AutoLock auto_lock(lock_);
-    // When the track is disabled, we simply return here.
-    // TODO(xians): Figure out if we should feed zero to sinks instead, in
-    // order to inject VAD data in such case.
-    if (!enabled())
-      return;
+    is_enabled = enabled();
 
     capturer = capturer_;
     voe_channels = voe_channels_;
@@ -180,7 +177,16 @@ void WebRtcLocalAudioTrack::Capture(media::AudioBus* audio_source,
   int current_volume = volume;
   while (current_buffer->Consume()) {
     // Feed the data to the sinks.
-    for (SinkList::const_iterator it = sinks.begin(); it != sinks.end(); ++it) {
+    SinkList::iterator first = sinks.begin();
+    SinkList::iterator last = sinks.begin();
+    if (!is_enabled) {
+      // Don't call capture sinks which are actually renderers.
+      last = std::remove_if(first, last,

[ajm, 2013/09/28 01:52:22]

Not sure if this will do the right thing; I haven't tested it.

+          [](const scoped_refptr<WebRtcAudioCapturerSinkOwner>& owner) {
+            return owner->HasRenderer();
+          });
+    }
+    for (SinkList::const_iterator it = first; it != last; ++it) {
       int new_volume = (*it)->CaptureData(voe_channels,
                                           current_buffer->buffer(),
                                           sample_rate,