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

ash/shelf/app_list_shelf_item_delegate.cc

 // 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.
 
 #include "ash/shelf/app_list_shelf_item_delegate.h"
 
 #include "ash/launcher/launcher_model.h"
 #include "ash/shell.h"
 #include "grit/ash_strings.h"
 #include "ui/base/l10n/l10n_util.h"
@@ skipping 18 matching lines @@
 
 base::string16 AppListShelfItemDelegate::GetTitle() {
   LauncherModel* model = Shell::GetInstance()->launcher_model();
   DCHECK(model);
   return model->status() == LauncherModel::STATUS_LOADING ?
       l10n_util::GetStringUTF16(IDS_AURA_APP_LIST_SYNCING_TITLE) :
       l10n_util::GetStringUTF16(IDS_AURA_APP_LIST_TITLE);
 }
 
 ui::MenuModel* AppListShelfItemDelegate::CreateContextMenu(
-    aura::RootWindow* root_window) {
+    aura::Window* root_window) {
   return NULL;
 }
 
 LauncherMenuModel* AppListShelfItemDelegate::CreateApplicationMenu(
     int event_flags) {
   // AppList does not show an application menu.
   return NULL;
 }
 
 bool AppListShelfItemDelegate::IsDraggable() {
   return false;
 }
 
 bool AppListShelfItemDelegate::ShouldShowTooltip() {
   return true;
 }
 
 }  // namespace internal
 }  // namespace ash