am a8313e71: Merge "Fix String16 operator+ to actually work"

* commit 'a8313e71fe8b483448d14e22610101c5f3672744':
  Fix String16 operator+ to actually work
diff --git a/include/utils/RefBase.h b/include/utils/RefBase.h
index 0af7e6a..d92cfb0 100644
--- a/include/utils/RefBase.h
+++ b/include/utils/RefBase.h
@@ -115,7 +115,6 @@
     // used to override the RefBase destruction.
     class Destroyer {
         friend class RefBase;
-        friend class weakref_type;
     public:
         virtual ~Destroyer();
     private: