Second patch in making destructors of refcounted objects private.

net/base/host_resolver.h

 // Copyright (c) 2006-2008 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_BASE_HOST_RESOLVER_H_
 #define NET_BASE_HOST_RESOLVER_H_
 
 #include <string>
 
 #include "base/ref_counted.h"
@@ skipping 86 matching lines @@
 
     // Called when request |id| has been cancelled. A request is "cancelled"
     // if either the HostResolver is destroyed while a resolution is in
     // progress, or HostResolver::CancelRequest() is called.
     virtual void OnCancelResolution(int id, const RequestInfo& info) = 0;
   };
 
   // Opaque type used to cancel a request.
   typedef void* RequestHandle;
 
-  // If any completion callbacks are pending when the resolver is destroyed,
-  // the host resolutions are cancelled, and the completion callbacks will not
-  // be called.
-  virtual ~HostResolver() {}
-
   // Resolves the given hostname (or IP address literal), filling out the
   // |addresses| object upon success.  The |info.port| parameter will be set as
   // the sin(6)_port field of the sockaddr_in{6} struct.  Returns OK if
   // successful or an error code upon failure.
   //
   // When callback is null, the operation completes synchronously.
   //
   // When callback is non-null, the operation may be performed asynchronously.
   // If the operation cannnot be completed synchronously, ERR_IO_PENDING will
   // be returned and the real result code will be passed to the completion
@@ skipping 28 matching lines @@
   // TODO(eroman): temp hack for http://crbug.com/18373
   virtual void Shutdown() = 0;
 
   // Sets the default AddressFamily to use when requests have left it
   // unspecified. For example, this could be used to restrict resolution
   // results to AF_INET by passing in ADDRESS_FAMILY_IPV4, or to
   // AF_INET6 by passing in ADDRESS_FAMILY_IPV6.
   virtual void SetDefaultAddressFamily(AddressFamily address_family) {}
 
  protected:
+  friend class base::RefCountedThreadSafe<HostResolver>;
+
   HostResolver() { }
 
+  // If any completion callbacks are pending when the resolver is destroyed,
+  // the host resolutions are cancelled, and the completion callbacks will not
+  // be called.
+  virtual ~HostResolver() {}
+
  private:
   DISALLOW_COPY_AND_ASSIGN(HostResolver);
 };
 
 // This class represents the task of resolving a hostname (or IP address
 // literal) to an AddressList object.  It wraps HostResolver to resolve only a
 // single hostname at a time and cancels this request when going out of scope.
 class SingleRequestHostResolver {
  public:
   explicit SingleRequestHostResolver(HostResolver* resolver);
@@ skipping 29 matching lines @@
 };
 
 // Creates a HostResolver implementation that queries the underlying system.
 // (Except if a unit-test has changed the global HostResolverProc using
 // ScopedHostResolverProc to intercept requests to the system).
 HostResolver* CreateSystemHostResolver();
 
 }  // namespace net
 
 #endif  // NET_BASE_HOST_RESOLVER_H_