Add MessageChanneFactory interface and use it in ChannelDispatcherBase.

remoting/protocol/ice_connection_to_host.h

Index: remoting/protocol/ice_connection_to_host.h
diff --git a/remoting/protocol/ice_connection_to_host.h b/remoting/protocol/ice_connection_to_host.h
index 2fcdbdd86888d2da46301b456efd8f5af29f0243..8cab97e2e406047dadeb5c61a5e690061669fe2c 100644
--- a/remoting/protocol/ice_connection_to_host.h
+++ b/remoting/protocol/ice_connection_to_host.h
@@ -66,16 +66,12 @@ class IceConnectionToHost : public ConnectionToHost,
 
   // ChannelDispatcherBase::EventHandler interface.
   void OnChannelInitialized(ChannelDispatcherBase* channel_dispatcher) override;
-  void OnChannelError(ChannelDispatcherBase* channel_dispatcher,
-                      ErrorCode error) override;
 
   // MonitoredVideoStub::EventHandler interface.
   virtual void OnVideoChannelStatus(bool active);
 
   void NotifyIfChannelsReady();
 
-  void CloseOnError(ErrorCode error);
-
   // Closes the P2P connection.
   void CloseChannels();