Unify mustash display closing code paths.

services/ui/display/platform_screen_stub.h

 // Copyright 2016 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_DISPLAY_PLATFORM_SCREEN_STUB_H_
 #define SERVICES_UI_DISPLAY_PLATFORM_SCREEN_STUB_H_
 
 #include <stdint.h>
 
 #include "base/callback.h"
 #include "base/memory/weak_ptr.h"
 #include "services/ui/display/platform_screen.h"
 
 namespace display {
 
 // PlatformScreenStub provides the necessary functionality to configure a fixed
 // 1024x768 display for non-ozone platforms.
 class PlatformScreenStub : public PlatformScreen {
  public:
   PlatformScreenStub();
   ~PlatformScreenStub() override;
 
  private:
   // Fake creation of a single 1024x768 display.
   void FixedSizeScreenConfiguration();
 
   // PlatformScreen.
   void AddInterfaces(shell::InterfaceRegistry* registry) override;
   void Init(PlatformScreenDelegate* delegate) override;
+  void RequestCloseDisplay(int64_t display_id) override;
   int64_t GetPrimaryDisplayId() const override;
 
   PlatformScreenDelegate* delegate_ = nullptr;
 
   base::WeakPtrFactory<PlatformScreenStub> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformScreenStub);
 };
 
 }  // namespace display
 
 #endif  // SERVICES_UI_DISPLAY_PLATFORM_SCREEN_STUB_H_