Objects that derive from RefCounted/RefCountedThreadSafe should not have public dtors.

base/threading/worker_pool_posix.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.
 //
 // The thread pool used in the POSIX implementation of WorkerPool dynamically
 // adds threads as necessary to handle all tasks.  It keeps old threads around
 // for a period of time to allow them to be reused.  After this waiting period,
 // the threads exit.  This thread pool uses non-joinable threads, therefore
 // worker threads are not joined during process shutdown.  This means that
 // potentially long running tasks (such as DNS lookup) do not block process
@@ skipping 35 matching lines @@
 
 class BASE_EXPORT PosixDynamicThreadPool
     : public RefCountedThreadSafe<PosixDynamicThreadPool> {
  public:
   class PosixDynamicThreadPoolPeer;
 
   // All worker threads will share the same |name_prefix|.  They will exit after
   // |idle_seconds_before_exit|.
   PosixDynamicThreadPool(const std::string& name_prefix,
                          int idle_seconds_before_exit);
-  ~PosixDynamicThreadPool();
 
   // Indicates that the thread pool is going away.  Stops handing out tasks to
   // worker threads.  Wakes up all the idle threads to let them exit.
   void Terminate();
 
   // Adds |task| to the thread pool.
   void PostTask(const tracked_objects::Location& from_here,
                 const Closure& task);
 
   // Worker thread method to wait for up to |idle_seconds_before_exit| for more
   // work from the thread pool.  Returns NULL if no work is available.
   PendingTask WaitForTask();
 
  private:
+  friend class RefCountedThreadSafe<PosixDynamicThreadPool>;
   friend class PosixDynamicThreadPoolPeer;
 
+  ~PosixDynamicThreadPool();
+
   // Adds pending_task to the thread pool.  This function will clear
   // |pending_task->task|.
   void AddTask(PendingTask* pending_task);
 
   const std::string name_prefix_;
   const int idle_seconds_before_exit_;
 
   Lock lock_;  // Protects all the variables below.
 
   // Signal()s worker threads to let them know more tasks are available.
   // Also used for Broadcast()'ing to worker threads to let them know the pool
   // is being deleted and they can exit.
   ConditionVariable pending_tasks_available_cv_;
   int num_idle_threads_;
   TaskQueue pending_tasks_;
   bool terminated_;
   // Only used for tests to ensure correct thread ordering.  It will always be
   // NULL in non-test code.
   scoped_ptr<ConditionVariable> num_idle_threads_cv_;
 
   DISALLOW_COPY_AND_ASSIGN(PosixDynamicThreadPool);
 };
 
 }  // namespace base
 
 #endif  // BASE_THREADING_WORKER_POOL_POSIX_H_