Update window_parenting_utils to use aura::window

ash/common/wm/window_parenting_utils.h

 // Copyright 2016 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_COMMON_WM_WINDOW_PARENTING_UTILS_H_
 #define ASH_COMMON_WM_WINDOW_PARENTING_UTILS_H_
 
+namespace aura {
+class Window;
+}
+
 namespace ash {
 
-class WmWindow;
-
 namespace wm {
 
 // Changes the parent of a |child| and all its transient children that are
 // themselves children of |old_parent| to |new_parent|.
-void ReparentChildWithTransientChildren(WmWindow* child,
-                                        WmWindow* old_parent,
-                                        WmWindow* new_parent);
+void ReparentChildWithTransientChildren(aura::Window* child,
+                                        aura::Window* old_parent,
+                                        aura::Window* new_parent);
 
 // Changes the parent of all transient children of a |child| to |new_parent|.
 // Does not change parent of the transient children that are not themselves
 // children of |old_parent|.
-void ReparentTransientChildrenOfChild(WmWindow* child,
-                                      WmWindow* old_parent,
-                                      WmWindow* new_parent);
+void ReparentTransientChildrenOfChild(aura::Window* child,
+                                      aura::Window* old_parent,
+                                      aura::Window* new_parent);
 
 }  // namespace wm
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_WINDOW_PARENTING_UTILS_H_