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

ash/wm/panels/panel_layout_manager.h

 // 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.
 
 #ifndef ASH_WM_PANELS_PANEL_LAYOUT_MANAGER_H_
 #define ASH_WM_PANELS_PANEL_LAYOUT_MANAGER_H_
 
 #include <list>
 
 #include "ash/ash_export.h"
@@ skipping 75 matching lines @@
   virtual void OnWindowRemovedFromLayout(aura::Window* child) OVERRIDE;
   virtual void OnChildWindowVisibilityChanged(aura::Window* child,
                                               bool visibile) OVERRIDE;
   virtual void SetChildBounds(aura::Window* child,
                               const gfx::Rect& requested_bounds) OVERRIDE;
 
   // Overridden from ash::LauncherIconObserver
   virtual void OnLauncherIconPositionsChanged() OVERRIDE;
 
   // Overridden from ash::ShellObserver
-  virtual void OnShelfAlignmentChanged(aura::RootWindow* root_window) OVERRIDE;
+  virtual void OnShelfAlignmentChanged(aura::Window* root_window) OVERRIDE;
 
   // Overridden from ash::wm::WindowStateObserver
   virtual void OnWindowShowTypeChanged(wm::WindowState* window_state,
                                        wm::WindowShowType old_type) OVERRIDE;
 
   // Overridden from aura::WindowObserver
   virtual void OnWindowVisibilityChanged(aura::Window* window,
                                          bool visible) OVERRIDE;
 
   // Overridden from aura::client::ActivationChangeObserver
@@ skipping 76 matching lines @@
   aura::Window* last_active_panel_;
   base::WeakPtrFactory<PanelLayoutManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PanelLayoutManager);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_PANELS_PANEL_LAYOUT_MANAGER_H_