Implements the GetSignalLevel and GetStats interface for the local audio track.

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 0b06c11c2907dcb38bdb7f4032f8846450fa1580..d28a9ba2a82d605a0629d6651c3cce0c61f2a911 100644
--- a/content/renderer/media/webrtc_local_audio_track.cc
+++ b/content/renderer/media/webrtc_local_audio_track.cc
@@ -6,6 +6,7 @@
 
 #include "content/public/renderer/media_stream_audio_sink.h"
 #include "content/renderer/media/media_stream_audio_level_calculator.h"
+#include "content/renderer/media/media_stream_audio_processor.h"
 #include "content/renderer/media/media_stream_audio_sink_owner.h"
 #include "content/renderer/media/media_stream_audio_track_sink.h"
 #include "content/renderer/media/peer_connection_audio_sink_owner.h"
@@ -113,6 +114,18 @@ void WebRtcLocalAudioTrack::OnSetFormat(
   sinks_.TagAll();
 }
 
+void WebRtcLocalAudioTrack::SetAudioProcessor(
+    const scoped_refptr<MediaStreamAudioProcessor>& processor) {
+  // if the |processor| does not have audio processing, which can happen if
+  // kEnableAudioTrackProcessing is not set or all the constraints in
+  // the |processor| are turned off. In such case, we pass NULL to the
+  // adapter to indicate that no stats can be gotten from the processor.
+  if (processor->has_audio_processing())
+    adapter_->SetAudioProcessor(processor.get());
+  else
+    adapter_->SetAudioProcessor(NULL);

[tommi (sloooow) - chröme, 2014/03/04 17:33:54]

nit: for fewer call sites and less code:
adapter_->SetAudioProcessor(
    processor->has_audio_processing() ? processor.get() : NULL);

also, if you change SetAudioProcessor to use chrome's scoped_refptr, you won't
need the call to .get().

[no longer working on chromium, 2014/03/04 18:54:07]

Done.

+}
+
 void WebRtcLocalAudioTrack::AddSink(MediaStreamAudioSink* sink) {
   DCHECK(main_render_thread_checker_.CalledOnValidThread());
   DVLOG(1) << "WebRtcLocalAudioTrack::AddSink()";