Reland r113263 rebased after revert of r113249.

net/disk_cache/backend_impl.cc

 // 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.
 
 #include "net/disk_cache/backend_impl.h"
 
 #include "base/bind.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/message_loop.h"
@@ skipping 1419 matching lines @@
   return net::ERR_IO_PENDING;
 }
 
 int BackendImpl::OpenNextEntry(void** iter, Entry** next_entry,
                                OldCompletionCallback* callback) {
   DCHECK(callback);
   background_queue_.OpenNextEntry(iter, next_entry, callback);
   return net::ERR_IO_PENDING;
 }
 
+int BackendImpl::OpenNextEntry(void** iter, Entry** next_entry,
+                               const net::CompletionCallback& callback) {
+  DCHECK(!callback.is_null());
+  background_queue_.OpenNextEntry(iter, next_entry, callback);
+  return net::ERR_IO_PENDING;
+}
+
 void BackendImpl::EndEnumeration(void** iter) {
   background_queue_.EndEnumeration(*iter);
   *iter = NULL;
 }
 
 void BackendImpl::GetStats(StatsItems* stats) {
   if (disabled_)
     return;
 
   std::pair<std::string, std::string> item;
@@ skipping 798 matching lines @@
     if (total_memory > kMaxBuffersSize || total_memory <= 0)
       total_memory = kMaxBuffersSize;
 
     done = true;
   }
 
   return static_cast<int>(total_memory);
 }
 
 }  // namespace disk_cache