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

ash/wm/dock/docked_window_resizer.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/dock/docked_window_resizer.h"
 
 #include "ash/ash_switches.h"
 #include "ash/display/display_controller.h"
 #include "ash/launcher/launcher.h"
 #include "ash/root_window_controller.h"
@@ skipping 24 matching lines @@
 namespace ash {
 namespace internal {
 
 namespace {
 
 DockedWindowLayoutManager* GetDockedLayoutManagerAtPoint(
     const gfx::Point& point) {
   gfx::Display display = ScreenAsh::FindDisplayContainingPoint(point);
   if (!display.is_valid())
     return NULL;
-  aura::RootWindow* root = Shell::GetInstance()->display_controller()->
+  aura::Window* root = Shell::GetInstance()->display_controller()->
       GetRootWindowForDisplayId(display.id());
   aura::Window* dock_container = Shell::GetContainer(
       root, kShellWindowId_DockedContainer);
   return static_cast<DockedWindowLayoutManager*>(
       dock_container->layout_manager());
 }
 
 }  // namespace
 
 DockedWindowResizer::~DockedWindowResizer() {
@@ skipping 233 matching lines @@
   // If we started the drag in one root window and moved into another root
   // but then canceled the drag we may need to inform the original layout
   // manager that the drag is finished.
   if (initial_dock_layout_ != dock_layout_)
     initial_dock_layout_->FinishDragging();
   is_docked_ = false;
 }
 
 }  // namespace internal
 }  // namespace ash