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

ash/screensaver/screensaver_view.cc

 // 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.
 
 #include "ash/screensaver/screensaver_view.h"
 
 #include "ash/shell.h"
 #include "ash/shell_delegate.h"
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 125 matching lines @@
 
 void ScreensaverView::LoadScreensaver() {
   screensaver_webview_->GetWebContents()->GetController().LoadURL(
         url_,
         content::Referrer(),
         content::PAGE_TRANSITION_AUTO_TOPLEVEL,
         std::string());
 }
 
 void ScreensaverView::ShowWindow() {
-  aura::RootWindow* root_window = ash::Shell::GetPrimaryRootWindow();
+  aura::Window* root_window = ash::Shell::GetPrimaryRootWindow();
   gfx::Rect screen_rect =
       Shell::GetScreen()->GetDisplayNearestWindow(root_window).bounds();
 
   // We want to be the fullscreen topmost child of the root window.
   // There should be nothing ever really that should show up on top of us.
   container_window_ = new views::Widget();
   views::Widget::InitParams params(
       views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
   params.delegate = this;
   params.parent = root_window;
   container_window_->Init(params);
 
   container_window_->StackAtTop();
   container_window_->SetBounds(screen_rect);
   container_window_->Show();
 }
 
 // static
 ScreensaverView* ScreensaverView::GetInstance() {
   return g_instance;
 }
 
 }  // namespace internal
 }  // namespace ash