ui: Cleanup class/struct forward declarations

ui/app_list/views/app_list_item_view.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_APP_LIST_VIEWS_APP_LIST_ITEM_VIEW_H_
 #define UI_APP_LIST_VIEWS_APP_LIST_ITEM_VIEW_H_
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/strings/string16.h"
 #include "base/timer/timer.h"
 #include "ui/app_list/app_list_export.h"
 #include "ui/app_list/app_list_item_observer.h"
 #include "ui/app_list/views/image_shadow_animator.h"
 #include "ui/views/context_menu_controller.h"
 #include "ui/views/controls/button/custom_button.h"
 
-class SkBitmap;
-
 namespace views {
 class ImageView;
 class Label;
 class MenuRunner;
 class ProgressBar;
 }
 
 namespace app_list {
 
 class AppListItem;
@@ skipping 136 matching lines @@
 
   // A timer to defer showing drag UI when mouse is pressed.
   base::OneShotTimer mouse_drag_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListItemView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_VIEWS_APP_LIST_ITEM_VIEW_H_