Convert //ash from scoped_ptr to std::unique_ptr

ash/wm/screen_dimmer.h

 // Copyright (c) 2012 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_WM_SCREEN_DIMMER_H_
 #define ASH_WM_SCREEN_DIMMER_H_
 
 #include "ash/ash_export.h"
 #include "ash/shell_observer.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 #include "ui/aura/window_observer.h"
 
 namespace ui {
 class Layer;
 }
 
 namespace ash {
 class DimWindow;
 
 // ScreenDimmer displays a partially-opaque layer above everything
@@ skipping 43 matching lines @@
   // Are we currently dimming the screen?
   bool is_dimming_;
   bool at_bottom_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenDimmer);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_SCREEN_DIMMER_H_