Update ICE protocol to handle closed channel

remoting/protocol/ice_connection_to_host.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/protocol/ice_connection_to_host.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 157 matching lines @@
   session_->Close(error);
 }
 
 void IceConnectionToHost::OnChannelInitialized(
     ChannelDispatcherBase* channel_dispatcher) {
   NotifyIfChannelsReady();
 }
 
 void IceConnectionToHost::OnChannelClosed(
     ChannelDispatcherBase* channel_dispatcher) {
-  // ICE transport doesn't close channels dynamically.
-  NOTREACHED();
+  session_->Close(OK);
 }
 
 void IceConnectionToHost::OnVideoChannelStatus(bool active) {
   event_callback_->OnConnectionReady(active);
 }
 
 ConnectionToHost::State IceConnectionToHost::state() const {
   return state_;
 }
 
@@ skipping 33 matching lines @@
 
   if (state != state_) {
     state_ = state;
     error_ = error;
     event_callback_->OnConnectionState(state_, error_);
   }
 }
 
 }  // namespace protocol
 }  // namespace remoting