Update window_parenting_utils to use aura::window

ash/common/wm/dock/docked_window_layout_manager.cc

Index: ash/common/wm/dock/docked_window_layout_manager.cc
diff --git a/ash/common/wm/dock/docked_window_layout_manager.cc b/ash/common/wm/dock/docked_window_layout_manager.cc
index ef6478be372ffa61a4481fd2119ccc5e0867e35c..157c53abb7dbb960bed537cdfeccc2d761ec4d4d 100644
--- a/ash/common/wm/dock/docked_window_layout_manager.cc
+++ b/ash/common/wm/dock/docked_window_layout_manager.cc
@@ -184,8 +184,9 @@ void UndockWindow(WmWindow* window) {
   WmWindow* old_parent = window->GetParent();
   window->SetParentUsingContext(window, gfx::Rect());
   if (window->GetParent() != old_parent) {
-    wm::ReparentTransientChildrenOfChild(window, old_parent,
-                                         window->GetParent());
+    wm::ReparentTransientChildrenOfChild(window->aura_window(),
+                                         old_parent->aura_window(),

[sky, 2017/03/09 20:57:45]

Similar comment about nullness for old_parent and GetParent().

[yiyix, 2017/03/09 22:00:15]

Done.

+                                         window->GetParent()->aura_window());
   }
   // Start maximize or fullscreen (affecting packaged apps) animation from
   // previous window bounds.