win: Ref-counted classes should have non-public destructors.

net/proxy/dhcp_proxy_script_fetcher_win.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.
 
 #ifndef NET_PROXY_DHCP_PROXY_SCRIPT_FETCHER_WIN_H_
 #define NET_PROXY_DHCP_PROXY_SCRIPT_FETCHER_WIN_H_
 
 #include <set>
 #include <string>
 
@@ skipping 45 matching lines @@
 
   scoped_refptr<base::TaskRunner> GetTaskRunner();
 
   // This inner class encapsulate work done on a worker pool thread.
   // The class calls GetCandidateAdapterNames, which can take a couple of
   // hundred milliseconds.
   class NET_EXPORT_PRIVATE AdapterQuery
       : public base::RefCountedThreadSafe<AdapterQuery> {
    public:
     AdapterQuery();
-    virtual ~AdapterQuery();
 
     // This is the method that runs on the worker pool thread.
     void GetCandidateAdapterNames();
 
     // This set is valid after GetCandidateAdapterNames has
     // been run. Its lifetime is scoped by this object.
     const std::set<std::string>& adapter_names() const;
 
    protected:
     // Virtual method introduced to allow unit testing.
     virtual bool ImplGetCandidateAdapterNames(
         std::set<std::string>* adapter_names);
 
+    friend class base::RefCountedThreadSafe<AdapterQuery>;
+    virtual ~AdapterQuery();
+
    private:
     // This is constructed on the originating thread, then used on the
     // worker thread, then used again on the originating thread only when
     // the task has completed on the worker thread. No locking required.
     std::set<std::string> adapter_names_;
 
     DISALLOW_COPY_AND_ASSIGN(AdapterQuery);
   };
 
   // Virtual methods introduced to allow unit testing.
@@ skipping 79 matching lines @@
 
   // Worker pool we use for all DHCP lookup tasks.
   scoped_refptr<base::SequencedWorkerPool> worker_pool_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(DhcpProxyScriptFetcherWin);
 };
 
 }  // namespace net
 
 #endif  // NET_PROXY_DHCP_PROXY_SCRIPT_FETCHER_WIN_H_