Add support for dynamic channels in WebrtcTransport.

remoting/protocol/webrtc_connection_to_client.h

Index: remoting/protocol/webrtc_connection_to_client.h
diff --git a/remoting/protocol/webrtc_connection_to_client.h b/remoting/protocol/webrtc_connection_to_client.h
index 31495cc3342bce0d5d61e24d30955c688b08fdb7..07e7d1e537bf0c7da519e0fd754e62b990ac182e 100644
--- a/remoting/protocol/webrtc_connection_to_client.h
+++ b/remoting/protocol/webrtc_connection_to_client.h
@@ -56,6 +56,9 @@ class WebrtcConnectionToClient : public ConnectionToClient,
   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(
@@ -63,6 +66,7 @@ class WebrtcConnectionToClient : public ConnectionToClient,
 
   // ChannelDispatcherBase::EventHandler interface.
   void OnChannelInitialized(ChannelDispatcherBase* channel_dispatcher) override;
+  void OnChannelClosed(ChannelDispatcherBase* channel_dispatcher) override;
 
  private:
   base::ThreadChecker thread_checker_;