Standardize Screen::GetCursorScreenPoint() on Env::last_mouse_location

ash/mus/screen_mus.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 ASH_MUS_SCREEN_MUS_H_
 #define ASH_MUS_SCREEN_MUS_H_
 
 #include "base/macros.h"
 #include "ui/display/screen_base.h"
 
 namespace ash {
 
 // Implementation of Screen for mus. The WindowManager/RootWindowController
 // keep the set of displays in sync (by modifying display_list()). This class
 // exists to provide implementations of ScreenBase functions that are
 // NOTIMPLEMENTED.
 // TODO(sky): implement remaining functions or merge with ScreenAsh:
 // http://crbug.com/671408.
 class ScreenMus : public display::ScreenBase {
  public:
   ScreenMus();
   ~ScreenMus() override;
 
  private:
   // display::ScreenBase:
   display::Display GetDisplayNearestWindow(aura::Window* window) const override;
+  gfx::Point GetCursorScreenPoint() override;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenMus);
 };
 
 }  // namespace ash
 
 #endif  // ASH_MUS_SCREEN_MUS_H_