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

ash/wm/overview/window_selector_item.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_item.h"
 #include "base/auto_reset.h"
 #include "ui/aura/window.h"
 
 namespace ash {
 
 WindowSelectorItem::WindowSelectorItem()
     : root_window_(NULL),
       in_bounds_update_(false) {
 }
 
 WindowSelectorItem::~WindowSelectorItem() {
 }
 
-void WindowSelectorItem::SetBounds(aura::RootWindow* root_window,
+void WindowSelectorItem::SetBounds(aura::Window* root_window,
                                    const gfx::Rect& target_bounds) {
   if (in_bounds_update_)
     return;
   base::AutoReset<bool> auto_reset_in_bounds_update(&in_bounds_update_, true);
   root_window_ = root_window;
   target_bounds_ = target_bounds;
   SetItemBounds(root_window, target_bounds, true);
 }
 
 void WindowSelectorItem::RecomputeWindowTransforms() {
   if (in_bounds_update_ || target_bounds_.IsEmpty())
     return;
   DCHECK(root_window_);
   base::AutoReset<bool> auto_reset_in_bounds_update(&in_bounds_update_, true);
   SetItemBounds(root_window_, target_bounds_, false);
 }
 
 }  // namespace ash