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

webrtc/media/engine/webrtcvoiceengine.cc

Index: webrtc/media/engine/webrtcvoiceengine.cc
diff --git a/webrtc/media/engine/webrtcvoiceengine.cc b/webrtc/media/engine/webrtcvoiceengine.cc
index 2cd19e7435e884ceefe2c801cd8070b12977948c..d83c205c8bcc5713bdb101a7f84884a0bfa97a6e 100644
--- a/webrtc/media/engine/webrtcvoiceengine.cc
+++ b/webrtc/media/engine/webrtcvoiceengine.cc
@@ -2312,6 +2312,11 @@ void WebRtcVoiceMediaChannel::OnRtcpReceived(
   }
 }
 
+void WebRtcVoiceMediaChannel::OnReadyToSend(bool ready) {
+  LOG(LS_VERBOSE) << "OnReadyToSend: " << (ready ? "Ready." : "Not ready.");
+  call_->SignalNetworkState(ready ? webrtc::kNetworkUp : webrtc::kNetworkDown);
+}
+
 bool WebRtcVoiceMediaChannel::MuteStream(uint32_t ssrc, bool muted) {
   RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
   int channel = GetSendChannelId(ssrc);