Makes display roots be destroyed by client

services/ui/demo/mus_demo.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_DEMO_MUS_DEMO_H_
 #define SERVICES_UI_DEMO_MUS_DEMO_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 42 matching lines @@
   bool OnWmSetBounds(Window* window, gfx::Rect* bounds) override;
   bool OnWmSetProperty(
       Window* window,
       const std::string& name,
       std::unique_ptr<std::vector<uint8_t>>* new_data) override;
   Window* OnWmCreateTopLevelWindow(
       std::map<std::string, std::vector<uint8_t>>* properties) override;
   void OnWmClientJankinessChanged(const std::set<Window*>& client_windows,
                                   bool janky) override;
   void OnWmNewDisplay(Window* window, const display::Display& display) override;
+  void OnWmDisplayRemoved(ui::Window* window) override;
   void OnWmPerformMoveLoop(Window* window,
                            mojom::MoveLoopSource source,
                            const gfx::Point& cursor_location,
                            const base::Callback<void(bool)>& on_done) override;
   void OnWmCancelMoveLoop(Window* window) override;
 
   // Allocate a bitmap the same size as the window to draw into.
   void AllocBitmap();
 
   // Draws one frame, incrementing the rotation angle.
@@ skipping 15 matching lines @@
   // Current rotation angle for drawing.
   double angle_ = 0.0;
 
   DISALLOW_COPY_AND_ASSIGN(MusDemo);
 };
 
 }  // namespace demo
 }  // namespace ui
 
 #endif  // SERVICES_UI_DEMO_MUS_DEMO_H_