RefCounted types should not have public destructors, base/ edition

base/synchronization/waitable_event_watcher.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_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_
 #define BASE_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_
 #pragma once
 
 #include "base/base_export.h"
 #include "build/build_config.h"
@@ skipping 54 matching lines @@
     : public MessageLoop::DestructionObserver
 #endif
 {
  public:
 
   WaitableEventWatcher();
   virtual ~WaitableEventWatcher();
 
   class BASE_EXPORT Delegate {
    public:
-    virtual ~Delegate() { }
-
     // -------------------------------------------------------------------------
     // This is called on the MessageLoop thread when WaitableEvent has been
     // signaled.
     //
     // Note: the event may not be signaled by the time that this function is
     // called. This indicates only that it has been signaled at some point in
     // the past.
     // -------------------------------------------------------------------------
     virtual void OnWaitableEventSignaled(WaitableEvent* waitable_event) = 0;
+
+   protected:
+    virtual ~Delegate() { }
   };
 
   // ---------------------------------------------------------------------------
   // When @event is signaled, the given delegate is called on the thread of the
   // current message loop when StartWatching is called. The delegate is not
   // deleted.
   // ---------------------------------------------------------------------------
   bool StartWatching(WaitableEvent* event, Delegate* delegate);
 
   // ---------------------------------------------------------------------------
@@ skipping 59 matching lines @@
 #endif
 
   WaitableEvent* event_;
 
   Delegate* delegate_;
 };
 
 }  // namespace base
 
 #endif  // BASE_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_