Added views::ViewModelT<T>, a type-safe template version of ViewModel.

ui/app_list/views/app_list_folder_view.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 UI_APP_LIST_VIEWS_APP_LIST_FOLDER_VIEW_H_
 #define UI_APP_LIST_VIEWS_APP_LIST_FOLDER_VIEW_H_
 
 #include <string>
 
 #include "ui/app_list/app_list_item_list_observer.h"
 #include "ui/app_list/views/apps_grid_view.h"
 #include "ui/app_list/views/apps_grid_view_folder_delegate.h"
 #include "ui/app_list/views/folder_header_view.h"
 #include "ui/app_list/views/folder_header_view_delegate.h"
 #include "ui/compositor/layer_animation_observer.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/view.h"
-
-namespace views {
-class ViewModel;
-}
+#include "ui/views/view_model.h"
 
 namespace app_list {
 
 class AppsContainerView;
 class AppsGridView;
 class AppListFolderItem;
 class AppListItemView;
 class AppListMainView;
 class AppListModel;
 class FolderHeaderView;
@@ skipping 89 matching lines @@
   bool hide_for_reparent_;
 
   base::string16 accessible_name_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListFolderView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_VIEWS_APP_LIST_FOLDER_VIEW_H_