Store AppItems as pages in AppListModel.

ui/app_list/app_list_item_model.h

Index: ui/app_list/app_list_item_model.h
diff --git a/ui/app_list/app_list_item_model.h b/ui/app_list/app_list_item_model.h
index 859b348fe98f2a0f5a7774d5b0ee7d66654b9a28..0ad9e93ca0e5c2dc75629354c9e86dd81c081580 100644
--- a/ui/app_list/app_list_item_model.h
+++ b/ui/app_list/app_list_item_model.h
@@ -9,6 +9,7 @@
 
 #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"
 
@@ -46,6 +47,10 @@ class APP_LIST_EXPORT AppListItemModel {
   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);
@@ -68,6 +73,7 @@ class APP_LIST_EXPORT AppListItemModel {
 
  private:
   const std::string id_;
+  syncer::StringOrdinal position_;
   gfx::ImageSkia icon_;
   bool has_shadow_;
   std::string title_;