Refactors DimWindow and moves to ash/common

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/common/shell_observer.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "ui/aura/window_observer.h"
 
 namespace ui {
 class Layer;
 }
 
 namespace ash {
 class DimWindow;
 
 // ScreenDimmer displays a partially-opaque layer above everything
 // else in the given container window to darken the display.  It shouldn't be
 // used for long-term brightness adjustments due to performance
 // considerations -- it's only intended for cases where we want to
 // briefly dim the screen (e.g. to indicate to the user that we're
 // about to suspend a machine that lacks an internal backlight that
 // can be adjusted).
-class ASH_EXPORT ScreenDimmer : ShellObserver {
+class ASH_EXPORT ScreenDimmer : public ShellObserver {
  public:
   // Creates a screen dimmer for the containers given by |container_id|.
   // It's owned by the container in the primary root window and will be
   // destroyed when the container is destroyed.
   static ScreenDimmer* GetForContainer(int container_id);
 
   // Creates a dimmer a root window level. This is used for suspend animation.
   static ScreenDimmer* GetForRoot();
 
   ~ScreenDimmer() override;
@@ skipping 26 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_