chromeos: Move files in //ash/common to //ash, part 2

ash/common/wm/window_parenting_utils.cc

-// 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.
-
-#include "ash/common/wm/window_parenting_utils.h"
-
-#include "ash/common/wm_window.h"
-
-namespace ash {
-namespace wm {
-
-void ReparentChildWithTransientChildren(WmWindow* child,
-                                        WmWindow* old_parent,
-                                        WmWindow* new_parent) {
-  if (child->GetParent() == old_parent)
-    new_parent->AddChild(child);
-  ReparentTransientChildrenOfChild(child, old_parent, new_parent);
-}
-
-void ReparentTransientChildrenOfChild(WmWindow* child,
-                                      WmWindow* old_parent,
-                                      WmWindow* new_parent) {
-  for (WmWindow* transient_child : child->GetTransientChildren())
-    ReparentChildWithTransientChildren(transient_child, old_parent, new_parent);
-}
-
-}  // namespace wm
-}  // namespace ash