Add polling and audio check to copresence.

components/copresence/mediums/audio/audio_player_impl.cc

Index: components/copresence/mediums/audio/audio_player_impl.cc
diff --git a/components/copresence/mediums/audio/audio_player_impl.cc b/components/copresence/mediums/audio/audio_player_impl.cc
index d84d6a1f9fab6a3ad672c3c442d8ecbf80a59e9f..dcc41b332944eb79809ce02c6613c365eed696fd 100644
--- a/components/copresence/mediums/audio/audio_player_impl.cc
+++ b/components/copresence/mediums/audio/audio_player_impl.cc
@@ -110,6 +110,7 @@ void AudioPlayerImpl::PlayOnAudioThread(
       return;
   }
 
+  VLOG(3) << "Starting playback.";
   is_playing_ = true;
   stream_->Start(this);
 }
@@ -119,6 +120,7 @@ void AudioPlayerImpl::StopOnAudioThread() {
   if (!stream_)
     return;
 
+  VLOG(3) << "Stopping playback.";
   stream_->Stop();
   is_playing_ = false;
 }