Centralizes more shared code between ash and mash

ash/aura/wm_root_window_controller_aura.cc

Index: ash/aura/wm_root_window_controller_aura.cc
diff --git a/ash/aura/wm_root_window_controller_aura.cc b/ash/aura/wm_root_window_controller_aura.cc
index 7217ba22d53a8c6b560d17df0e5170f9cf283acf..eae1b44e73b537f6b35adf561b158dde6cc91211 100644
--- a/ash/aura/wm_root_window_controller_aura.cc
+++ b/ash/aura/wm_root_window_controller_aura.cc
@@ -67,10 +67,6 @@ WmShell* WmRootWindowControllerAura::GetShell() {
   return WmShell::Get();
 }
 
-AlwaysOnTopController* WmRootWindowControllerAura::GetAlwaysOnTopController() {
-  return root_window_controller_->always_on_top_controller();
-}
-
 WmShelf* WmRootWindowControllerAura::GetShelf() {
   return root_window_controller_->wm_shelf_aura();
 }
@@ -118,4 +114,9 @@ void WmRootWindowControllerAura::OnWallpaperAnimationFinished(
   WmRootWindowController::OnWallpaperAnimationFinished(widget);
 }
 
+bool WmRootWindowControllerAura::ShouldDestroyWindowInCloseChildWindows(
+    WmWindow* window) {
+  return WmWindowAura::GetAuraWindow(window)->owned_by_parent();
+}
+
 }  // namespace ash