Make GetRootWindow() return a Window instead of a RootWindow.

ash/shelf/app_list_shelf_item_delegate.h

 // Copyright 2013 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 ASH_SHELF_APP_LIST_SHELF_ITEM_DELEGATE_H_
 #define ASH_SHELF_APP_LIST_SHELF_ITEM_DELEGATE_H_
 
 #include "ash/launcher/launcher_item_delegate.h"
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 
 namespace ash {
 namespace internal {
 
 // LauncherItemDelegate for TYPE_APP_LIST.
 class AppListShelfItemDelegate : public LauncherItemDelegate {
  public:
   AppListShelfItemDelegate();
 
   virtual ~AppListShelfItemDelegate();
 
   // ash::LauncherItemDelegate overrides:
   virtual void ItemSelected(const ui::Event& event) OVERRIDE;
   virtual base::string16 GetTitle() OVERRIDE;
   virtual ui::MenuModel* CreateContextMenu(
-      aura::RootWindow* root_window) OVERRIDE;
+      aura::Window* root_window) OVERRIDE;
   virtual LauncherMenuModel* CreateApplicationMenu(int event_flags) OVERRIDE;
   virtual bool IsDraggable() OVERRIDE;
   virtual bool ShouldShowTooltip() OVERRIDE;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AppListShelfItemDelegate);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SHELF_APP_LIST_SHELF_ITEM_DELEGATE_H_