Reorder the NativeViews attached to a view via kViewHostKey according to the position of the view

ui/views/widget/widget.h

Index: ui/views/widget/widget.h
diff --git a/ui/views/widget/widget.h b/ui/views/widget/widget.h
index 51a5de14a973d64e8bb8dfb294937d2c9e2e9275..4a2f06f4ac3f5ebd6500e758bcd30ad1176eae9c 100644
--- a/ui/views/widget/widget.h
+++ b/ui/views/widget/widget.h
@@ -577,6 +577,10 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
   // Invokes method of same name on the NativeWidget.
   void ReorderLayers();
 
+  // Returns true if a child NativeView is attached to one of the widget's
+  // views.
+  bool HasNativeViewAttachedToViewTree() const;
+
   // Schedules an update to the root layers. The actual processing occurs when
   // GetRootLayers() is invoked.
   void UpdateRootLayers();