Add support for dynamic channels in WebrtcTransport.

remoting/protocol/webrtc_connection_to_host.h

Index: remoting/protocol/webrtc_connection_to_host.h
diff --git a/remoting/protocol/webrtc_connection_to_host.h b/remoting/protocol/webrtc_connection_to_host.h
index 8410fa56239dbee91a27989be8e1f50582d22455..75e0397de83645de83e5baebd3f86cdff52f42af 100644
--- a/remoting/protocol/webrtc_connection_to_host.h
+++ b/remoting/protocol/webrtc_connection_to_host.h
@@ -55,6 +55,9 @@ class WebrtcConnectionToHost : public ConnectionToHost,
   void OnWebrtcTransportConnecting() override;
   void OnWebrtcTransportConnected() override;
   void OnWebrtcTransportError(ErrorCode error) override;
+  void OnWebrtcTransportIncomingDataChannel(
+      const std::string& name,
+      std::unique_ptr<MessagePipe> pipe) override;
   void OnWebrtcTransportMediaStreamAdded(
       scoped_refptr<webrtc::MediaStreamInterface> stream) override;
   void OnWebrtcTransportMediaStreamRemoved(
@@ -62,6 +65,7 @@ class WebrtcConnectionToHost : public ConnectionToHost,
 
   // ChannelDispatcherBase::EventHandler interface.
   void OnChannelInitialized(ChannelDispatcherBase* channel_dispatcher) override;
+  void OnChannelClosed(ChannelDispatcherBase* channel_dispatcher) override;
 
   void NotifyIfChannelsReady();