Virtual destructors should have virtual keyword.

net/http/http_cache.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.
 
 // This file declares a HttpTransactionFactory implementation that can be
 // layered on top of another HttpTransactionFactory to add HTTP caching.  The
 // caching logic follows RFC 2616 (any exceptions are called out in the code).
 //
 // The HttpCache takes a disk_cache::Backend as a parameter, and uses that for
 // the cache storage.
@@ skipping 126 matching lines @@
   HttpCache(HttpNetworkSession* session, BackendFactory* backend_factory);
 
   // Initialize the cache from its component parts, which is useful for
   // testing.  The lifetime of the network_layer and backend_factory are managed
   // by the HttpCache and will be destroyed using |delete| when the HttpCache is
   // destroyed.
   HttpCache(HttpTransactionFactory* network_layer,
             NetLog* net_log,
             BackendFactory* backend_factory);
 
-  ~HttpCache();
+  virtual ~HttpCache();
 
   HttpTransactionFactory* network_layer() { return network_layer_.get(); }
 
   // Retrieves the cache backend for this HttpCache instance. If the backend
   // is not initialized yet, this method will initialize it. The return value is
   // a network error code, and it could be ERR_IO_PENDING, in which case the
   // |callback| will be notified when the operation completes. The pointer that
   // receives the |backend| must remain valid until the operation completes.
   int GetBackend(disk_cache::Backend** backend, CompletionCallback* callback);
 
@@ skipping 215 matching lines @@
   ScopedRunnableMethodFactory<HttpCache> task_factory_;
 
   scoped_ptr<PlaybackCacheMap> playback_cache_map_;
 
   DISALLOW_COPY_AND_ASSIGN(HttpCache);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_CACHE_H_