Implement client-side video stream support for WebRTC-based protocol.

remoting/protocol/webrtc_transport.cc

Index: remoting/protocol/webrtc_transport.cc
diff --git a/remoting/protocol/webrtc_transport.cc b/remoting/protocol/webrtc_transport.cc
index cf3235e38addeb1e45118184933dd44f3cf8840f..76336cc7e4c5f2bd170d3b3792d4237b9485a38d 100644
--- a/remoting/protocol/webrtc_transport.cc
+++ b/remoting/protocol/webrtc_transport.cc
@@ -348,12 +348,12 @@ void WebrtcTransport::OnSignalingChange(
 
 void WebrtcTransport::OnAddStream(webrtc::MediaStreamInterface* stream) {
   DCHECK(thread_checker_.CalledOnValidThread());
-  LOG(ERROR) << "Stream added " << stream->label();
+  event_handler_->OnWebrtcTransportMediaStreamAdded(stream);
 }
 
 void WebrtcTransport::OnRemoveStream(webrtc::MediaStreamInterface* stream) {
   DCHECK(thread_checker_.CalledOnValidThread());
-  LOG(ERROR) << "Stream removed " << stream->label();
+  event_handler_->OnWebrtcTransportMediaStreamRemoved(stream);
 }
 
 void WebrtcTransport::OnDataChannel(