Makes windowserver not send messages during shutdown

services/ui/ws/window_tree.cc

 // Copyright 2014 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 "services/ui/ws/window_tree.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 164 matching lines @@
 }
 
 DisplayManager* WindowTree::display_manager() {
   return window_server_->display_manager();
 }
 
 const DisplayManager* WindowTree::display_manager() const {
   return window_server_->display_manager();
 }
 
+void WindowTree::PrepareForWindowServerShutdown() {
+  window_manager_internal_client_binding_.reset();
+  binding_->ResetClientForShutdown();
+  if (window_manager_internal_)
+    window_manager_internal_ = binding_->GetWindowManager();
+}
+
 void WindowTree::AddRootForWindowManager(const ServerWindow* root) {
   DCHECK(window_manager_internal_);
   const ClientWindowId client_window_id(WindowIdToTransportId(root->id()));
   DCHECK_EQ(0u, client_id_to_window_id_map_.count(client_window_id));
   client_id_to_window_id_map_[client_window_id] = root->id();
   window_id_to_client_id_map_[root->id()] = client_window_id;
   roots_.insert(root);
 
   Display* display = GetDisplay(root);
   DCHECK(display);
@@ skipping 1670 matching lines @@
   client()->OnCompleteDrop(client_window_id.id, event_flags, cursor_offset,
                            effect_bitmask, callback);
 }
 
 void WindowTree::PerformOnDragDropDone() {
   client()->OnDragDropDone();
 }
 
 }  // namespace ws
 }  // namespace ui