ui: Cleanup class/struct forward declarations

ui/app_list/views/all_apps_tile_item_view.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 UI_APP_LIST_VIEWS_ALL_APPS_TILE_ITEM_VIEW_H_
 #define UI_APP_LIST_VIEWS_ALL_APPS_TILE_ITEM_VIEW_H_
 
 #include <vector>
 
 #include "ui/app_list/views/tile_item_view.h"
 
 namespace app_list {
 
-class AppListItemList;
 class ContentsView;
 
 // A tile item for the "All apps" button on the start page.
 class AllAppsTileItemView : public TileItemView {
  public:
   explicit AllAppsTileItemView(ContentsView* contents_view);
 
   ~AllAppsTileItemView() override;
 
   void UpdateIcon();
 
   // TileItemView overrides:
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
  private:
   ContentsView* contents_view_;
 
   DISALLOW_COPY_AND_ASSIGN(AllAppsTileItemView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_VIEWS_ALL_APPS_TILE_ITEM_VIEW_H_