aura: Implement new app list mock.

ash/app_list/app_list_model.h

 // Copyright (c) 2011 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_APP_LIST_APP_LIST_MODEL_H_
 #define ASH_APP_LIST_APP_LIST_MODEL_H_
 #pragma once
 
-#include "ash/app_list/app_list_item_group_model.h"
+#include "ash/app_list/app_list_item_model.h"
 #include "base/basictypes.h"
 #include "ash/ash_export.h"
 #include "ui/base/models/list_model.h"
 
 namespace ash {
 
 // Model for AppListView. It is consisted of a list of AppListItemGroupModels,
 // which in turn owns a list of AppListItemModels.
 class ASH_EXPORT AppListModel {
  public:
+  typedef ui::ListModel<AppListItemModel> Items;
+
   AppListModel();
   virtual ~AppListModel();
 
-  void AddGroup(AppListItemGroupModel* group);
-  AppListItemGroupModel* GetGroup(int index);
+  void AddItem(AppListItemModel* item);
+  AppListItemModel* GetItem(int index);
 
   void AddObserver(ui::ListModelObserver* observer);
   void RemoveObserver(ui::ListModelObserver* observer);
 
-  int group_count() const {
-    return groups_.item_count();
+  int item_count() const {
+    return items_.item_count();
   }
 
  private:
-  ui::ListModel<AppListItemGroupModel> groups_;
+  Items items_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListModel);
 };
 
 }  // namespace ash
 
 #endif  // ASH_APP_LIST_APP_LIST_MODEL_H_