RefCounted types should not have public destructors, delegate cleanup

content/public/browser/worker_service_observer.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 CONTENT_PUBLIC_BROWSER_WORKER_SERVICE_OBSERVER_H_
 #define CONTENT_PUBLIC_BROWSER_WORKER_SERVICE_OBSERVER_H_
 #pragma once
 
 #include "base/process.h"
 #include "base/string16.h"
 
 class GURL;
 
 namespace content {
 
 class WorkerServiceObserver {
  public:
-  virtual ~WorkerServiceObserver() {}
-
   virtual void WorkerCreated(const GURL& url,
                              const string16& name,
                              int process_id,
                              int route_id) {}
   virtual void WorkerDestroyed(int process_id, int route_id) {}
+
+ protected:
+  virtual ~WorkerServiceObserver() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WORKER_SERVICE_OBSERVER_H_