Make the audio channel communicate network state changes to the call.

webrtc/call/call.cc

Index: webrtc/call/call.cc
diff --git a/webrtc/call/call.cc b/webrtc/call/call.cc
index 41ac328eab14f44249a20d7ac0dba85a36bb9d1d..5c95d7941f8675828bfee7b962b082a88d1293c3 100644
--- a/webrtc/call/call.cc
+++ b/webrtc/call/call.cc
@@ -550,6 +550,10 @@ void Call::SetBitrateConfig(
 
 void Call::SignalNetworkState(NetworkState state) {
   RTC_DCHECK(configuration_thread_checker_.CalledOnValidThread());
+  // TODO(skvlad): In the unbundled case the network state might be different

[pbos-webrtc, 2016/03/03 10:18:57]

Can you add this now? I think it's scary that audio down can bring down video
(scarier than sending audio even though audio is down). You can add a MediaType
parameter to this method and only make the state disabled if both media types
are down. That should cover the bundle case right now without potentially
breaking unbundle.

[stefan-webrtc, 2016/03/03 10:23:53]

+1, I agree we need to fix this now if we are going to submit this CL.

+  // for the audio and video channels. Currently the last change wins.
+  // Correctly handling this scenario would require tracking the network state
+  // for each media type separately.
   network_enabled_ = state == kNetworkUp;
   congestion_controller_->SignalNetworkState(state);
   {