views: Make view::Views::GetPreferredSize() const.

ui/app_list/views/contents_switcher_view.h

 // Copyright 2014 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_CONTENTS_SWITCHER_VIEW_H_
 #define UI_APP_LIST_VIEWS_CONTENTS_SWITCHER_VIEW_H_
 
 #include "base/basictypes.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/view.h"
 
 namespace app_list {
 
 class ContentsView;
 
 // A view that contains buttons to switch the displayed view in the given
 // ContentsView.
 class ContentsSwitcherView : public views::View, public views::ButtonListener {
  public:
   explicit ContentsSwitcherView(ContentsView* contents_view);
   virtual ~ContentsSwitcherView();
 
  private:
   // Adds a switcher button using |resource_id| as the button's image and |tag|
   // as the button's id.
   void AddSwitcherButton(int resource_id, int tag);
 
   // Overridden from views::View:
-  virtual gfx::Size GetPreferredSize() OVERRIDE;
+  virtual gfx::Size GetPreferredSize() const OVERRIDE;
   virtual void Layout() OVERRIDE;
 
   // Overridden from views::ButtonListener:
   virtual void ButtonPressed(views::Button* sender,
                              const ui::Event& event) OVERRIDE;
 
   ContentsView* contents_view_;  // Owned by views hierarchy.
   views::View* buttons_;         // Owned by views hierarchy.
 
   DISALLOW_COPY_AND_ASSIGN(ContentsSwitcherView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_VIEWS_CONTENTS_SWITCHER_VIEW_H_