Makes display roots be destroyed by client

services/ui/public/interfaces/window_manager.mojom

 // 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.
 
 module ui.mojom;
 
 import "services/ui/public/interfaces/cursor.mojom";
 import "services/ui/public/interfaces/display/display.mojom";
 import "services/ui/public/interfaces/event_matcher.mojom";
 import "services/ui/public/interfaces/window_manager_constants.mojom";
@@ skipping 57 matching lines @@
 
   // Called immediately when the WindowManager is obtained.
   OnConnect(uint16 client_id);
 
   // Called when a new display is added. |root| gives the root window specific
   // to this WindowManager for |display|.
   WmNewDisplayAdded(display.mojom.Display display,
                     WindowData root,
                     bool parent_drawn);
 
+  // Called when a display is removed. The root of the specified display is
+  // still valid. It is expected the client calls DeleteWindow() shortly after
+  // this with the root.
+  WmDisplayRemoved(int64 display_id);
+
   // When the WindowManager completes a request it must call back to
   // WindowManagerClient::WmResponse().
   WmSetBounds(uint32 change_id, uint32 window_id, gfx.mojom.Rect bounds);
   WmSetProperty(uint32 change_id,
                 uint32 window_id,
                 string name,
                 array<uint8>? value);
   
   // Asks the WindowManager to create a new window.
   // |requesting_client_id| is the id of the client issuing the request. This
@@ skipping 68 matching lines @@
   WmSetNonClientCursor(uint32 window_id, Cursor cursor_id);
 
   // Response from WmCreateTopLevelWindow() informing the client of the id for
   // the new window.
   OnWmCreatedTopLevelWindow(uint32 change_id, uint32 window_id);
 
   // See description in WindowManager::OnAccelerator(). |ack_id| is the value
   // that was passed to OnAccelerator().
   OnAcceleratorAck(uint32 ack_id, EventResult event_result);
 };