RefCounted types should not have public destructors, base/ edition

base/memory/weak_ptr.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Weak pointers help in cases where you have many objects referring back to a
 // shared object and you wish for the lifetime of the shared object to not be
 // bound to the lifetime of the referrers.  In other words, this is useful when
 // reference counting is not a good fit.
 //
 // Thread-safety notes:
@@ skipping 233 matching lines @@
 
   WeakPtr<T> AsWeakPtr() {
     return WeakPtr<T>(weak_reference_owner_.GetRef(), static_cast<T*>(this));
   }
 
   // Indicates that this object will be used on another thread from now on.
   void DetachFromThread() {
     weak_reference_owner_.DetachFromThread();
   }
 
+ protected:
+  ~SupportsWeakPtr() {}
+
  private:
   internal::WeakReferenceOwner weak_reference_owner_;
   DISALLOW_COPY_AND_ASSIGN(SupportsWeakPtr);
 };
 
 // Helper function that uses type deduction to safely return a WeakPtr<Derived>
 // when Derived doesn't directly extend SupportsWeakPtr<Derived>, instead it
 // extends a Base that extends SupportsWeakPtr<Base>.
 //
 // EXAMPLE:
@@ skipping 55 matching lines @@
 
  private:
   internal::WeakReferenceOwner weak_reference_owner_;
   T* ptr_;
   DISALLOW_IMPLICIT_CONSTRUCTORS(WeakPtrFactory);
 };
 
 }  // namespace base
 
 #endif  // BASE_MEMORY_WEAK_PTR_H_