ui: Cleanup class/struct forward declarations

ui/views/controls/glow_hover_controller.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 UI_VIEWS_CONTROLS_GLOW_HOVER_CONTROLLER_H_
 #define UI_VIEWS_CONTROLS_GLOW_HOVER_CONTROLLER_H_
 
 #include "base/macros.h"
 #include "ui/gfx/animation/animation_delegate.h"
 #include "ui/gfx/animation/slide_animation.h"
 #include "ui/views/views_export.h"
 
 namespace gfx {
-class Canvas;
-class ImageSkia;
 class Point;
 }
 
 namespace views {
 
 class View;
 
 // GlowHoverController is responsible for drawing a hover effect as is used by
 // the tabstrip. Typical usage:
 //   OnMouseEntered() -> invoke Show().
@@ skipping 53 matching lines @@
   // Location of the glow, relative to view.
   gfx::Point location_;
   double opacity_scale_;
 
   DISALLOW_COPY_AND_ASSIGN(GlowHoverController);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_GLOW_HOVER_CONTROLLER_H_