mus: Make sure window parenting happens in the window server.

services/ui/ws/window_server.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_SERVER_H_
 #define SERVICES_UI_WS_WINDOW_SERVER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 205 matching lines @@
   void StartDragLoop(uint32_t change_id,
                      ServerWindow* window,
                      WindowTree* initiator);
   void EndDragLoop();
   uint32_t GetCurrentDragLoopChangeId();
   ServerWindow* GetCurrentDragLoopWindow();
   WindowTree* GetCurrentDragLoopInitiator();
   bool in_drag_loop() const { return !!current_drag_loop_; }
 
   void OnDisplayReady(Display* display, bool is_first);
+  void OnDisplayDestroyed(Display* display);
   void OnNoMoreDisplays();
   WindowManagerState* GetWindowManagerStateForUser(const UserId& user_id);
 
   // ServerWindowDelegate:
   cc::mojom::DisplayCompositor* GetDisplayCompositor() override;
   const cc::SurfaceId& GetRootSurfaceId() const override;
 
   // UserDisplayManagerDelegate:
   bool GetFrameDecorationsForUser(
       const UserId& user_id,
@@ skipping 145 matching lines @@
   // State for rendering into a Surface.
   cc::mojom::DisplayCompositorPtr display_compositor_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowServer);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_WINDOW_SERVER_H_