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

ash/test/test_launcher_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/test/test_launcher_item_delegate.h"
 
 #include "ash/wm/window_util.h"
 #include "ui/aura/window.h"
 
 namespace ash {
@@ skipping 13 matching lines @@
     window_->Show();
     ash::wm::ActivateWindow(window_);
   }
 }
 
 base::string16 TestLauncherItemDelegate::GetTitle() {
   return window_ ? window_->title() : base::string16();
 }
 
 ui::MenuModel* TestLauncherItemDelegate::CreateContextMenu(
-    aura::RootWindow* root_window) {
+    aura::Window* root_window) {
   return NULL;
 }
 
 ash::LauncherMenuModel* TestLauncherItemDelegate::CreateApplicationMenu(
     int event_flags) {
   return NULL;
 }
 
 bool TestLauncherItemDelegate::IsDraggable() {
   return true;
 }
 
 bool TestLauncherItemDelegate::ShouldShowTooltip() {
   return true;
 }
 
 }  // namespace test
 }  // namespace ash