Plumb network stack information about existence of cached copy

net/http/http_cache.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.
 
 // 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 177 matching lines @@
 
   // Initializes the Infinite Cache, if selected by the field trial.
   void InitializeInfiniteCache(const base::FilePath& path);
 
   // HttpTransactionFactory implementation:
   virtual int CreateTransaction(RequestPriority priority,
                                 scoped_ptr<HttpTransaction>* trans) OVERRIDE;
   virtual HttpCache* GetCache() OVERRIDE;
   virtual HttpNetworkSession* GetSession() OVERRIDE;
 
+  // Resets the network layer to allow for tests that probe
+  // network changes (e.g. host unreachable).  The old network layer is
+  // returned to allow for filter patterns that only intercept
+  // some creation requests.  Note ownership exchange.
+  scoped_ptr<HttpTransactionFactory>
+      SetHttpNetworkTransactionFactoryForTesting(
+          scoped_ptr<HttpTransactionFactory> new_network_layer);
+
  protected:
   // Disk cache entry data indices.
   enum {
     kResponseInfoIndex = 0,
     kResponseContentIndex,
     kMetadataIndex,
 
     // Must remain at the end of the enum.
     kNumCacheEntryDataIndices
   };
@@ skipping 169 matching lines @@
   NetLog* net_log_;
 
   // Used when lazily constructing the disk_cache_.
   scoped_ptr<BackendFactory> backend_factory_;
   bool building_backend_;
 
   Mode mode_;
 
   const scoped_ptr<QuicServerInfoFactoryAdaptor> quic_server_info_factory_;
 
-  const scoped_ptr<HttpTransactionFactory> network_layer_;
+  scoped_ptr<HttpTransactionFactory> network_layer_;
+
   scoped_ptr<disk_cache::Backend> disk_cache_;
 
   // The set of active entries indexed by cache key.
   ActiveEntriesMap active_entries_;
 
   // The set of doomed entries.
   ActiveEntriesSet doomed_entries_;
 
   // The set of entries "under construction".
   PendingOpsMap pending_ops_;
 
   scoped_ptr<PlaybackCacheMap> playback_cache_map_;
 
   DISALLOW_COPY_AND_ASSIGN(HttpCache);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_CACHE_H_