WIP - loop in LayoutManager for preferred size changes

ui/views/view.h

Index: ui/views/view.h
diff --git a/ui/views/view.h b/ui/views/view.h
index 306e3a9a13545080abae056c6cab14ea8545c967..e32f00c8655233d220a14426e27f1ad1a96e89c2 100644
--- a/ui/views/view.h
+++ b/ui/views/view.h
@@ -943,11 +943,11 @@ class VIEWS_EXPORT View : public ui::LayerDelegate,
   // Size and disposition ------------------------------------------------------
 
   // Override to be notified when the bounds of the view have changed.
-  virtual void OnBoundsChanged(const gfx::Rect& previous_bounds);
+  virtual void OnBoundsChanged(const gfx::Rect& previous_bounds) {}
 
   // Called when the preferred size of a child view changed.  This gives the
   // parent an opportunity to do a fresh layout if that makes sense.
-  virtual void ChildPreferredSizeChanged(View* child) {}
+  virtual void ChildPreferredSizeChanged(View* child);
 
   // Called when the visibility of a child view changed.  This gives the parent
   // an opportunity to do a fresh layout if that makes sense.
@@ -1168,6 +1168,7 @@ class VIEWS_EXPORT View : public ui::LayerDelegate,
   friend class internal::PostEventDispatchHandler;
   friend class internal::RootView;
   friend class FocusManager;
+  friend class LayoutManager;
   friend class Widget;
 
   // Painting  -----------------------------------------------------------------