Find display root ServerWindow for located events in mus.

services/ui/ws/event_dispatcher_delegate.h

 // 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.
 
 #ifndef SERVICES_UI_WS_EVENT_DISPATCHER_DELEGATE_H_
 #define SERVICES_UI_WS_EVENT_DISPATCHER_DELEGATE_H_
 
 #include <stdint.h>
 
 #include "services/ui/common/types.h"
@@ skipping 48 matching lines @@
                                           ClientSpecificId client_id,
                                           const ui::Event& event,
                                           Accelerator* accelerator) = 0;
 
   // Returns the id of the client to send events to. |in_nonclient_area| is
   // true if the event occurred in the non-client area of the window.
   virtual ClientSpecificId GetEventTargetClientId(const ServerWindow* window,
                                                   bool in_nonclient_area) = 0;
 
   // Returns the window to start searching from at the specified location, or
-  // null if there is a no window containing |location|.
-  virtual ServerWindow* GetRootWindowContaining(const gfx::Point& location) = 0;
+  // null if there is a no window containing |location|. |location| should be in
+  // screen coordinates and if a window is returned then |location| will be
+  // updated to be relative to the origin of the window.
+  virtual ServerWindow* GetRootWindowContaining(gfx::Point* location) = 0;
 
   // Called when event dispatch could not find a target. OnAccelerator may still
   // be called.
   virtual void OnEventTargetNotFound(const ui::Event& event) = 0;
 
  protected:
   virtual ~EventDispatcherDelegate() {}
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_EVENT_DISPATCHER_DELEGATE_H_