Refactor app list so AppsGridView owns the PaginationModel.

ui/app_list/views/page_switcher.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_VIEWS_PAGE_SWITCHER_H_
 #define UI_APP_LIST_VIEWS_PAGE_SWITCHER_H_
 
 #include "base/basictypes.h"
 #include "ui/app_list/pagination_model_observer.h"
 #include "ui/views/controls/button/button.h"
@@ skipping 15 matching lines @@
 
   // Returns the page index of the page switcher button under the point. If no
   // page switcher button is under the point, -1 is return. |point| is in
   // PageSwitcher's coordinates.
   int GetPageForPoint(const gfx::Point& point) const;
 
   // Shows hover for button under the point. |point| is in PageSwitcher's
   // coordinates.
   void UpdateUIForDragPoint(const gfx::Point& point);
 
+  // Disconnects the PageSwitcher from its underlying PaginationModel. Can be
+  // used if the PaginationModel is going to be destroyed.
+  void ReleasePaginationModel();
+
   // Overridden from views::View:
   virtual gfx::Size GetPreferredSize() const OVERRIDE;
   virtual void Layout() OVERRIDE;
 
  private:
   void CalculateButtonWidthAndSpacing(int contents_width);
 
   // Overridden from views::ButtonListener:
   virtual void ButtonPressed(views::Button* sender,
                              const ui::Event& event) OVERRIDE;
 
   // Overridden from PaginationModelObserver:
   virtual void TotalPagesChanged() OVERRIDE;
   virtual void SelectedPageChanged(int old_selected, int new_selected) OVERRIDE;
   virtual void TransitionStarted() OVERRIDE;
   virtual void TransitionChanged() OVERRIDE;
 
-  PaginationModel* model_;  // Owned by AppListController.
+  PaginationModel* model_;  // Owned by AppListController; may be NULL.

[xiyuan, 2014/05/30 15:47:47]

Update comments as |model_| is ownded by AppsGridView now.

[Matt Giuca, 2014/06/02 07:11:23]

Done.

   views::View* buttons_;  // Owned by views hierarchy.
 
   DISALLOW_COPY_AND_ASSIGN(PageSwitcher);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_VIEWS_PAGE_SWITCHER_H_