Split libjingle's signaling thread from the UI thread

content/renderer/media/peer_connection_tracker.cc

Index: content/renderer/media/peer_connection_tracker.cc
diff --git a/content/renderer/media/peer_connection_tracker.cc b/content/renderer/media/peer_connection_tracker.cc
index 2f2b584f41908598b3d91d51e8b4933238b502a6..e22ec976415a9a862b2ff7c4affdfe4db9d3809f 100644
--- a/content/renderer/media/peer_connection_tracker.cc
+++ b/content/renderer/media/peer_connection_tracker.cc
@@ -304,15 +304,17 @@ bool PeerConnectionTracker::OnControlMessageReceived(
 void PeerConnectionTracker::OnGetAllStats() {
   DCHECK(main_thread_.CalledOnValidThread());
 
+  const std::string empty_track_id;
   for (PeerConnectionIdMap::iterator it = peer_connection_id_map_.begin();
        it != peer_connection_id_map_.end(); ++it) {
     rtc::scoped_refptr<InternalStatsObserver> observer(
         new rtc::RefCountedObject<InternalStatsObserver>(it->second));
 
+    // The last type parameter is ignored when the track id is empty.
     it->first->GetStats(

[perkj_chrome, 2014/10/31 08:37:24]

oh, this is the reason there is a getStats and GetStats in PCHandler....
ok then....

[tommi (sloooow) - chröme, 2014/10/31 10:06:32]

Yup, I tried to remove it but yeah

         observer,
-        NULL,
-        webrtc::PeerConnectionInterface::kStatsOutputLevelDebug);
+        webrtc::PeerConnectionInterface::kStatsOutputLevelDebug,
+        empty_track_id, blink::WebMediaStreamSource::TypeAudio);
   }
 }