Refactor app list so AppsGridView owns the PaginationModel.

ash/wm/app_list_controller.h

Index: ash/wm/app_list_controller.h
diff --git a/ash/wm/app_list_controller.h b/ash/wm/app_list_controller.h
index 437cbb4a75020127ea3a665255e098f61be96e2d..d1b386f387fcfbd5943a4aad4a837cf2ec282cbe 100644
--- a/ash/wm/app_list_controller.h
+++ b/ash/wm/app_list_controller.h
@@ -125,8 +125,6 @@ class AppListController : public ui::EventHandler,
   virtual void TransitionStarted() OVERRIDE;
   virtual void TransitionChanged() OVERRIDE;
 
-  scoped_ptr<app_list::PaginationModel> pagination_model_;
-
   // Whether we should show or hide app list widget.
   bool is_visible_;
 
@@ -136,6 +134,13 @@ class AppListController : public ui::EventHandler,
   // The AppListView this class manages, owned by its widget.
   app_list::AppListView* view_;
 
+  // The pagination model owned by the AppListGridView of |view_|.
+  app_list::PaginationModel* pagination_model_;
+
+  // The current page of the AppListGridView of |view_|. This is stored outside
+  // of |pagination_model_|, so that it persists when the view is destroyed.
+  int current_app_page_;
+
   // Cached bounds of |view_| for snapping back animation after over-scroll.
   gfx::Rect view_bounds_;