Store AppItems as pages in AppListModel.

ui/app_list/views/apps_grid_view.h

Index: ui/app_list/views/apps_grid_view.h
diff --git a/ui/app_list/views/apps_grid_view.h b/ui/app_list/views/apps_grid_view.h
index 8d996a6c75f375060ed4bae0c6ea24e436866674..4747b9494736783505a01c679271eb8940266ea6 100644
--- a/ui/app_list/views/apps_grid_view.h
+++ b/ui/app_list/views/apps_grid_view.h
@@ -51,7 +51,6 @@ class PaginationModel;
 // AppsGridView displays a grid for AppListModel::Apps sub model.
 class APP_LIST_EXPORT AppsGridView : public views::View,
                                      public views::ButtonListener,
-                                     public ui::ListModelObserver,
                                      public PaginationModelObserver,
                                      public AppListModelObserver {
  public:
@@ -176,7 +175,7 @@ class APP_LIST_EXPORT AppsGridView : public views::View,
   // number of apps.
   void UpdatePulsingBlockViews();
 
-  views::View* CreateViewForItemAtIndex(size_t index);
+  views::View* CreateViewForItemAtIndex(size_t page_idx, size_t item_idx);
 
   // Convert between the model index and the visual index. The model index
   // is the index of the item in AppListModel. The visual index is the Index
@@ -250,12 +249,6 @@ class APP_LIST_EXPORT AppsGridView : public views::View,
   virtual void ButtonPressed(views::Button* sender,
                              const ui::Event& event) OVERRIDE;
 
-  // Overridden from ListModelObserver:
-  virtual void ListItemsAdded(size_t start, size_t count) OVERRIDE;
-  virtual void ListItemsRemoved(size_t start, size_t count) OVERRIDE;
-  virtual void ListItemMoved(size_t index, size_t target_index) OVERRIDE;
-  virtual void ListItemsChanged(size_t start, size_t count) OVERRIDE;
-
   // Overridden from PaginationModelObserver:
   virtual void TotalPagesChanged() OVERRIDE;
   virtual void SelectedPageChanged(int old_selected, int new_selected) OVERRIDE;
@@ -264,6 +257,12 @@ class APP_LIST_EXPORT AppsGridView : public views::View,
 
   // Overridden from AppListModelObserver:
   virtual void OnAppListModelStatusChanged() OVERRIDE;
+  virtual void OnListItemsAdded(size_t page_index,
+                                size_t start, size_t count) OVERRIDE;
+  virtual void OnListItemsRemoved(size_t page_index,
+                                  size_t start, size_t count) OVERRIDE;
+  virtual void OnListItemMoved(size_t page_index,
+                               size_t index, size_t target_index) OVERRIDE;
 
   // Hide a given view temporarily without losing (mouse) events and / or
   // changing the size of it. If |immediate| is set the change will be