--- a/src/core/callback.h	Tue Jul 08 10:02:57 2008 -0700
+++ b/src/core/callback.h	Tue Jul 08 10:10:26 2008 -0700
@@ -85,6 +85,7 @@
       delete this;
     }
   }
+  uint32_t GetReferenceCount (void) const { return m_count; }
   virtual bool IsEqual (Ptr<const CallbackImplBase> other) const = 0;
 private:
   mutable uint32_t m_count;