Store AppItems as pages in AppListModel.

ui/app_list/app_list_item_model.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_APP_LIST_ITEM_MODEL_H_
 #define UI_APP_LIST_APP_LIST_ITEM_MODEL_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/observer_list.h"
+#include "sync/api/string_ordinal.h"
 #include "ui/app_list/app_list_export.h"
 #include "ui/gfx/image/image_skia.h"
 
 namespace ui {
 class MenuModel;
 }
 
 namespace app_list {
 
 class AppListItemModelObserver;
@@ skipping 17 matching lines @@
   void SetHighlighted(bool highlighted);
   bool highlighted() const { return highlighted_; }
 
   void SetIsInstalling(bool is_installing);
   bool is_installing() const { return is_installing_; }
 
   void SetPercentDownloaded(int percent_downloaded);
   int percent_downloaded() const { return percent_downloaded_; }
 
   const std::string& id() const { return id_; }
+  const syncer::StringOrdinal& position() const { return position_; }
+  void set_position(syncer::StringOrdinal& new_position) {
+    position_ = new_position;

[xiyuan, 2013/10/18 23:04:08]

Should we add an observer method for this as well? It would be useful when the
position is from sync instead of MoveItem.

On the sync topic, we might want to keep track of the page ordinal here too. And
having a method in AppListModel to rebuild the paging structure from it.

[stevenjb, 2013/10/19 01:04:43]

Yes, when we sync this will need to be more than a trivial setter. Not sure we
need an observer, but thus will definitely change to SetPosition() and will take
a page index as well as an item ordinal.

+  }
 
   void AddObserver(AppListItemModelObserver* observer);
   void RemoveObserver(AppListItemModelObserver* observer);
 
   // Returns a string used for initially sorting the apps (used by
   // AppListModel::AddItem). Defaults to an empty string.
   virtual std::string GetSortOrder() const;
 
   // Activates (opens) the item. Does nothing by default.
   virtual void Activate(int event_flags);
 
   // Returns a static const char* identifier for the subclass (defaults to "").
   // Pointers can be compared for quick type checking.
   virtual const char* GetAppType() const;
 
   // Returns the context menu model for this item, or NULL if there is currently
   // no menu for the item (e.g. during install).
   // Note the returned menu model is owned by this item.
   virtual ui::MenuModel* GetContextMenuModel();
 
  private:
   const std::string id_;
+  syncer::StringOrdinal position_;
   gfx::ImageSkia icon_;
   bool has_shadow_;
   std::string title_;
   std::string full_name_;
   bool highlighted_;
   bool is_installing_;
   int percent_downloaded_;
 
   ObserverList<AppListItemModelObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListItemModel);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_APP_LIST_ITEM_MODEL_H_