Makes windowserver not send messages during shutdown

services/ui/ws/window_tree_binding.h

 // 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.
 
 #ifndef SERVICES_UI_WS_WINDOW_TREE_BINDING_H_
 #define SERVICES_UI_WS_WINDOW_TREE_BINDING_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 15 matching lines @@
   explicit WindowTreeBinding(mojom::WindowTreeClient* client);
   virtual ~WindowTreeBinding();
 
   mojom::WindowTreeClient* client() { return client_; }
 
   // Obtains a new WindowManager. This should only be called once.
   virtual mojom::WindowManager* GetWindowManager() = 0;
 
   virtual void SetIncomingMethodCallProcessingPaused(bool paused) = 0;
 
+  // Called when the WindowServer is destroyed. Sets |client_| to
+  // CreateClientForShutdown().
+  void ResetClientForShutdown();
+
+ protected:
+  virtual mojom::WindowTreeClient* CreateClientForShutdown() = 0;
+
  private:
   mojom::WindowTreeClient* client_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeBinding);
 };
 
 // Bindings implementation of WindowTreeBinding.
 class DefaultWindowTreeBinding : public WindowTreeBinding {
  public:
   DefaultWindowTreeBinding(WindowTree* tree,
                            WindowServer* window_server,
                            mojom::WindowTreeRequest service_request,
                            mojom::WindowTreeClientPtr client);
   DefaultWindowTreeBinding(WindowTree* tree,
                            mojom::WindowTreeClientPtr client);
   ~DefaultWindowTreeBinding() override;
 
   // Use when created with the constructor that does not take a
   // WindowTreeRequest.
   mojom::WindowTreePtr CreateInterfacePtrAndBind();
 
   // WindowTreeBinding:
   mojom::WindowManager* GetWindowManager() override;
   void SetIncomingMethodCallProcessingPaused(bool paused) override;
 
+ protected:
+  // WindowTreeBinding:
+  mojom::WindowTreeClient* CreateClientForShutdown() override;
+
  private:
   mojo::Binding<mojom::WindowTree> binding_;
   mojom::WindowTreeClientPtr client_;
   mojom::WindowManagerAssociatedPtr window_manager_internal_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultWindowTreeBinding);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_WINDOW_TREE_BINDING_H_