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

ash/wm/overview/window_selector_window.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/wm/overview/window_selector_window.h"
 
 #include "ui/aura/window.h"
 
 namespace ash {
 
 WindowSelectorWindow::WindowSelectorWindow(aura::Window* window)
     : transform_window_(window) {
 }
 
 WindowSelectorWindow::~WindowSelectorWindow() {
 }
 
-aura::RootWindow* WindowSelectorWindow::GetRootWindow() {
+aura::Window* WindowSelectorWindow::GetRootWindow() {
   return transform_window_.window()->GetRootWindow();
 }
 
 aura::Window* WindowSelectorWindow::TargetedWindow(const aura::Window* target) {
   if (transform_window_.Contains(target))
     return transform_window_.window();
   return NULL;
 }
 
 void WindowSelectorWindow::RestoreWindowOnExit(aura::Window* window) {
@@ skipping 10 matching lines @@
 }
 
 bool WindowSelectorWindow::empty() const {
   return transform_window_.window() == NULL;
 }
 
 void WindowSelectorWindow::PrepareForOverview() {
   transform_window_.PrepareForOverview();
 }
 
-void WindowSelectorWindow::SetItemBounds(aura::RootWindow* root_window,
+void WindowSelectorWindow::SetItemBounds(aura::Window* root_window,
                                          const gfx::Rect& target_bounds,
                                          bool animate) {
   gfx::Rect src_rect = transform_window_.GetBoundsInScreen();
   set_bounds(ScopedTransformOverviewWindow::
       ShrinkRectToFitPreservingAspectRatio(src_rect, target_bounds));
   transform_window_.SetTransform(root_window,
       ScopedTransformOverviewWindow::GetTransformForRect(src_rect, bounds()),
       animate);
 }
 
 }  // namespace ash