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..928787a8c7b2e008a64afd2470722ebadcad8ce5 100644
--- a/webrtc/media/engine/webrtcvoiceengine.cc
+++ b/webrtc/media/engine/webrtcvoiceengine.cc
@@ -1350,6 +1350,9 @@ WebRtcVoiceMediaChannel::WebRtcVoiceMediaChannel(WebRtcVoiceEngine* engine,
   RTC_DCHECK(call);
   engine->RegisterChannel(this);
   SetOptions(options);
+  call_->SignalChannelNetworkState(
+    webrtc::MediaType::AUDIO,
+    webrtc::ChannelNetworkState::CHANNEL_NETWORK_UP);
 }
 
 WebRtcVoiceMediaChannel::~WebRtcVoiceMediaChannel() {
@@ -1365,6 +1368,9 @@ WebRtcVoiceMediaChannel::~WebRtcVoiceMediaChannel() {
     RemoveRecvStream(recv_streams_.begin()->first);
   }
   engine()->UnregisterChannel(this);
+  call_->SignalChannelNetworkState(
+    webrtc::MediaType::AUDIO,
+    webrtc::ChannelNetworkState::CHANNEL_NOT_PRESENT);
 }
 
 rtc::DiffServCodePoint WebRtcVoiceMediaChannel::PreferredDscp() const {
@@ -2399,6 +2405,16 @@ bool WebRtcVoiceMediaChannel::SetSendBitrateInternal(int bps) {
   }
 }
 
+void WebRtcVoiceMediaChannel::OnReadyToSend(bool ready)
+{
+  LOG(LS_VERBOSE) << "OnReadyToSend: " << (ready ? "Ready." : "Not ready.");
+  call_->SignalChannelNetworkState(
+    webrtc::MediaType::AUDIO,
+    ready ?
+    webrtc::ChannelNetworkState::CHANNEL_NETWORK_UP :
+    webrtc::ChannelNetworkState::CHANNEL_NETWORK_DOWN);
+}
+
 bool WebRtcVoiceMediaChannel::GetStats(VoiceMediaInfo* info) {
   RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
   RTC_DCHECK(info);