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

base/message_pump.h

 // Copyright (c) 2011 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 BASE_MESSAGE_PUMP_H_
 #define BASE_MESSAGE_PUMP_H_
 #pragma once
 
 #include "base/base_export.h"
 #include "base/memory/ref_counted.h"
@@ skipping 25 matching lines @@
     // future delayed work (timer events) is currently empty, and no additional
     // calls to this function need to be scheduled.
     virtual bool DoDelayedWork(TimeTicks* next_delayed_work_time) = 0;
 
     // Called from within Run just before the message pump goes to sleep.
     // Returns true to indicate that idle work was done.
     virtual bool DoIdleWork() = 0;
   };
 
   MessagePump();
-  virtual ~MessagePump();
 
   // The Run method is called to enter the message pump's run loop.
   //
   // Within the method, the message pump is responsible for processing native
   // messages as well as for giving cycles to the delegate periodically.  The
   // message pump should take care to mix delegate callbacks with native
   // message processing so neither type of event starves the other of cycles.
   //
   // The anatomy of a typical run loop:
   //
@@ skipping 56 matching lines @@
   // Schedule a DoWork callback to happen reasonably soon.  Does nothing if a
   // DoWork callback is already scheduled.  This method may be called from any
   // thread.  Once this call is made, DoWork should not be "starved" at least
   // until it returns a value of false.
   virtual void ScheduleWork() = 0;
 
   // Schedule a DoDelayedWork callback to happen at the specified time,
   // cancelling any pending DoDelayedWork callback.  This method may only be
   // used on the thread that called Run.
   virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time) = 0;
+
+ protected:
+  virtual ~MessagePump();
+  friend class RefCountedThreadSafe<MessagePump>;
 };
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_PUMP_H_