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 d6bd9cf3606f74ee0e3dacc525fc8bb38e3fb3f0..6d951b575187c3239aeda8f3421db51ac74ca604 100644
--- a/ui/views/widget/widget.h
+++ b/ui/views/widget/widget.h
@@ -573,6 +573,13 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
   // Returns the widget's layer, if any.
   ui::Layer* GetLayer();
 
+  // Reorder the widget's child layers which belong to NativeViews attached to
+  // the view tree (eg via a NativeViewHost). The layers are reordered to match
+  // the order of views with layers / views with attached layers in the view
+  // tree. This method assumes that the layers which are owned by views are
+  // already correctly ordered relative to each other.
+  void ReorderLayersForAttachedNativeViews();
+
   // Schedules an update to the root layers. The actual processing occurs when
   // GetRootLayers() is invoked.
   void UpdateRootLayers();