EDK: Sprinkle some more |final| secret sauce.

mojo/edk/util/ref_ptr_internal.h

 // Copyright 2015 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.
 
 #ifndef MOJO_EDK_UTIL_REF_PTR_INTERNAL_H_
 #define MOJO_EDK_UTIL_REF_PTR_INTERNAL_H_
 
 #include <utility>
 
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
 namespace util {
 
 template <typename T>
 class RefPtr;
 
 template <typename T>
 RefPtr<T> AdoptRef(T* ptr);
 
 namespace internal {
 
 // This is a wrapper class that can be friended for a particular |T|, if you
 // want to make |T|'s constructor private, but still use |MakeRefCounted()|
 // (below). (You can't friend partial specializations.) See |MakeRefCounted()|
 // and |FRIEND_MAKE_REF_COUNTED()|.
 template <typename T>
-class MakeRefCountedHelper {
+class MakeRefCountedHelper final {
  public:
   template <typename... Args>
   static RefPtr<T> MakeRefCounted(Args&&... args) {
     return AdoptRef<T>(new T(std::forward<Args>(args)...));
   }
 };
 
 }  // namespace internal
 }  // namespace util
 }  // namespace mojo
 
 #endif  // MOJO_EDK_UTIL_REF_PTR_INTERNAL_H_