Reland r113263 rebased after revert of r113249.

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 113 matching lines @@
   // entries to enumerate. When the entry pointer is no longer needed, its
   // Close method should be called. The return value is a net error code. If
   // this method returns ERR_IO_PENDING, the |callback| will be invoked when the
   // |next_entry| is available. The pointer to receive the |next_entry| must
   // remain valid until the operation completes.
   //
   // NOTE: This method does not modify the last_used field of the entry, and
   // therefore it does not impact the eviction ranking of the entry.
   virtual int OpenNextEntry(void** iter, Entry** next_entry,
                             OldCompletionCallback* callback) = 0;
+  virtual int OpenNextEntry(void** iter, Entry** next_entry,
+                            const net::CompletionCallback& callback) = 0;
 
   // 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;
@@ skipping 155 matching lines @@
   // Note: This method is deprecated.
   virtual int ReadyForSparseIO(OldCompletionCallback* completion_callback) = 0;
 
  protected:
   virtual ~Entry() {}
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_DISK_CACHE_H_