Remove non-MD code from ShelfButton

ash/common/shelf/shelf_button.h

 // Copyright 2013 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_COMMON_SHELF_SHELF_BUTTON_H_
 #define ASH_COMMON_SHELF_SHELF_BUTTON_H_
 
 #include "ash/ash_export.h"
 #include "base/macros.h"
 #include "ui/gfx/shadow_value.h"
 #include "ui/views/controls/button/custom_button.h"
-#include "ui/views/controls/image_view.h"
+
+namespace views {
+class ImageView;
+}
 
 namespace ash {
 class InkDropButtonListener;
 class ShelfView;
 
 // Button used for items on the launcher, except for the AppList.
 class ASH_EXPORT ShelfButton : public views::CustomButton {
  public:
   static const char kViewClassName[];
 
@@ skipping 96 matching lines @@
   // If non-null the destuctor sets this to true. This is set while the menu is
   // showing and used to detect if the menu was deleted while running.
   bool* destroyed_flag_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfButton);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELF_SHELF_BUTTON_H_