Log audio system used to WebRTC log.

chromecast/media/audio/cast_audio_manager.cc

Index: chromecast/media/audio/cast_audio_manager.cc
diff --git a/chromecast/media/audio/cast_audio_manager.cc b/chromecast/media/audio/cast_audio_manager.cc
index 230a1f9695794b67d35ebe6b41bacda7112683cc..fbad984fea8ee3f12b9e8c5188e84687ede1b228 100644
--- a/chromecast/media/audio/cast_audio_manager.cc
+++ b/chromecast/media/audio/cast_audio_manager.cc
@@ -83,6 +83,10 @@ void CastAudioManager::GetAudioInputDeviceNames(
       ::media::CHANNEL_LAYOUT_STEREO, 48000, 16, 1024);
 }
 
+const char* CastAudioManager::GetName() {
+  return "Cast";
+}
+
 std::unique_ptr<MediaPipelineBackend>
 CastAudioManager::CreateMediaPipelineBackend(
     const MediaPipelineDeviceParams& params) {