Makes display roots be destroyed by client

services/ui/public/cpp/window_tree_client.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_PUBLIC_CPP_WINDOW_TREE_CLIENT_H_
 #define SERVICES_UI_PUBLIC_CPP_WINDOW_TREE_CLIENT_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 331 matching lines @@
   void OnChangeCompleted(uint32_t change_id, bool success) override;
   void RequestClose(uint32_t window_id) override;
   void GetWindowManager(
       mojo::AssociatedInterfaceRequest<WindowManager> internal) override;
 
   // Overridden from WindowManager:
   void OnConnect(ClientSpecificId client_id) override;
   void WmNewDisplayAdded(const display::Display& display,
                          mojom::WindowDataPtr root_data,
                          bool parent_drawn) override;
+  void WmDisplayRemoved(int64_t display_id) override;
   void WmSetBounds(uint32_t change_id,
                    Id window_id,
                    const gfx::Rect& transit_bounds) override;
   void WmSetProperty(uint32_t change_id,
                      Id window_id,
                      const mojo::String& name,
                      mojo::Array<uint8_t> transit_data) override;
   void WmCreateTopLevelWindow(uint32_t change_id,
                               ClientSpecificId requesting_client_id,
                               mojo::Map<mojo::String, mojo::Array<uint8_t>>
@@ skipping 104 matching lines @@
   std::set<Id> drag_entered_windows_;
 
   base::WeakPtrFactory<WindowTreeClient> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeClient);
 };
 
 }  // namespace ui
 
 #endif  // SERVICES_UI_PUBLIC_CPP_WINDOW_TREE_CLIENT_H_