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 9447364529732256dfdb4f70f68384a7b56785d7..816f1e8b9826fad53cfd8d74a7d67bd8095c6bd0 100644
--- a/ui/views/view.h
+++ b/ui/views/view.h
@@ -74,6 +74,15 @@ class PostEventDispatchHandler;
 class RootView;
 }
 
+class VIEWS_EXPORT ScopedMaybeLayout {
+ public:
+  ScopedMaybeLayout(views::View* view);
+  ~ScopedMaybeLayout();
+
+ private:
+  views::View* view_;
+};
+
 /////////////////////////////////////////////////////////////////////////////
 //
 // View class
@@ -975,11 +984,11 @@ 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.
@@ -1198,6 +1207,8 @@ class VIEWS_EXPORT View : public ui::LayerDelegate,
   friend class internal::PostEventDispatchHandler;
   friend class internal::RootView;
   friend class FocusManager;
+  friend class LayoutManager;
+  friend class ScopedMaybeLayout;
   friend class Widget;
 
   // Painting  -----------------------------------------------------------------