Inform disk cache of WebKit memory cache hits.

net/disk_cache/disk_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.
 
 // Defines the public interface of the disk cache. For more details see
 // http://dev.chromium.org/developers/design-documents/network-stack/disk-cache
 
 #ifndef NET_DISK_CACHE_DISK_CACHE_H_
 #define NET_DISK_CACHE_DISK_CACHE_H_
 #pragma once
@@ skipping 119 matching lines @@
 
   // Releases iter without returning the next entry. Whenever OpenNextEntry()
   // returns true, but the caller is not interested in continuing the
   // enumeration by calling OpenNextEntry() again, the enumeration must be
   // ended by calling this method with iter returned by OpenNextEntry().
   virtual void EndEnumeration(void** iter) = 0;
 
   // Return a list of cache statistics.
   virtual void GetStats(
       std::vector<std::pair<std::string, std::string> >* stats) = 0;
+
+  // Called whenever an external cache in the system reuses the resource
+  // referred to by |key|.
+  virtual void OnExternalCacheHit(const std::string& key) = 0;
 };
 
 // This interface represents an entry in the disk cache.
 class NET_TEST Entry {
  public:
   // Marks this cache entry for deletion.
   virtual void Doom() = 0;
 
   // Releases this entry. Calling this method does not cancel pending IO
   // operations on this entry. Even after the last reference to this object has
@@ skipping 141 matching lines @@
   // Note: This method is deprecated.
   virtual int ReadyForSparseIO(CompletionCallback* completion_callback) = 0;
 
  protected:
   virtual ~Entry() {}
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_DISK_CACHE_H_