ash: Cleanup class/struct forward declarations

ash/common/frame/default_header_painter.h

 // Copyright 2014 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_FRAME_DEFAULT_HEADER_PAINTER_H_
 #define ASH_COMMON_FRAME_DEFAULT_HEADER_PAINTER_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
 #include "ash/common/frame/header_painter.h"
 #include "base/compiler_specific.h"  // override
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/animation/animation_delegate.h"
 
 namespace gfx {
-class ImageSkia;
 class Rect;
 class SlideAnimation;
 }
 namespace views {
 class View;
 class Widget;
 }
 
 namespace ash {
 class FrameCaptionButtonContainerView;
@@ skipping 83 matching lines @@
   bool initial_paint_;
 
   std::unique_ptr<gfx::SlideAnimation> activation_animation_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultHeaderPainter);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_FRAME_DEFAULT_HEADER_PAINTER_H_