Update window_parenting_utils to use aura::window

ash/common/wm/default_state.cc

Index: ash/common/wm/default_state.cc
diff --git a/ash/common/wm/default_state.cc b/ash/common/wm/default_state.cc
index 8149d7f856fc21a1871835fbd425b90fb7595c3e..a084c521da3b66f173b26abd420c64af04cfd77e 100644
--- a/ash/common/wm/default_state.cc
+++ b/ash/common/wm/default_state.cc
@@ -701,8 +701,9 @@ void DefaultState::UpdateBoundsFromState(WindowState* window_state,
         WmWindow* docked_container =
             window->GetRootWindow()->GetChildByShellWindowId(
                 kShellWindowId_DockedContainer);
-        ReparentChildWithTransientChildren(window, window->GetParent(),
-                                           docked_container);
+        ReparentChildWithTransientChildren(window->aura_window(),
+                                           window->GetParent()->aura_window(),

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

It isn't readily obvious to me if GetParent() is non-null in all these
situations. I think it's safer to do window->aura_window()->parent(). This is
assuming you know window is non-null, which I believe it is. Please do this
change in the other files as well.

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

It is good to have as safe guard. Added.

+                                           docked_container->aura_window());
       }
       // Return early because we don't want to update the bounds of the
       // window below; as the bounds are managed by the dock layout.