RefCounted types should not have public destructors

base/memory/ref_counted.h

Index: base/memory/ref_counted.h
diff --git a/base/memory/ref_counted.h b/base/memory/ref_counted.h
index cf8ff1688dc7f4de093f78d15a17a1fade0ed0fe..fd4ed35b69e79172a2331408ef8a5aeb11b30f0d 100644
--- a/base/memory/ref_counted.h
+++ b/base/memory/ref_counted.h
@@ -164,6 +164,12 @@ class RefCountedData : public base::RefCounted< base::RefCountedData<T> > {
   RefCountedData(const T& in_value) : data(in_value) {}
 
   T data;
+
+ protected:
+  ~RefCountedData() {}

[darin (slow to review), 2012/05/22 18:01:31]

probably you want to make this destructor virtual or private.  otherwise,
someone will be sad if they try to inherit from RefCountedData.

[Ryan Sleevi, 2012/05/22 18:36:20]

See the thread I started on chromium-dev regarding destructors.

Making it private means that this cannot be inherited (as ResourceResponse wants
to do). Making it virtual seems to support polymorphic deletion, but that's
explicitly what we don't want to allow (see the chromium-dev thread).

This is following http://www.gotw.ca/publications/mill18.htm

" A base class destructor should be either public and virtual, or protected and
nonvirtual."

+
+ private:
+  friend class base::RefCounted<base::RefCountedData<T> >;
 };
 
 }  // namespace base