Unify mustash display closing code paths.

services/ui/ws/display.h

 // 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.
 
 #ifndef SERVICES_UI_WS_DISPLAY_H_
 #define SERVICES_UI_WS_DISPLAY_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 154 matching lines @@
   void CreateWindowManagerDisplayRootsFromFactories();
 
   void CreateWindowManagerDisplayRootFromFactory(
       WindowManagerWindowTreeFactory* factory);
 
   // PlatformDisplayDelegate:
   ServerWindow* GetRootWindow() override;
   bool IsInHighContrastMode() override;
   void OnEvent(const ui::Event& event) override;
   void OnNativeCaptureLost() override;
-  void OnDisplayClosed() override;
   void OnViewportMetricsChanged(const ViewportMetrics& old_metrics,
                                 const ViewportMetrics& new_metrics) override;
   void OnCompositorFrameDrawn() override;
 
   // FocusControllerDelegate:
   bool CanHaveActiveChildren(ServerWindow* window) const override;
 
   // FocusControllerObserver:
   void OnActivationChanged(ServerWindow* old_active_window,
                            ServerWindow* new_active_window) override;
@@ skipping 30 matching lines @@
 
   WindowManagerDisplayRootMap window_manager_display_root_map_;
 
   DISALLOW_COPY_AND_ASSIGN(Display);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_DISPLAY_H_