Introduce AppCacheResponseMetadataWriter to support metadata caching.

content/browser/appcache/appcache_storage_impl.cc

 // 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.
 
 #include "content/browser/appcache/appcache_storage_impl.h"
 
 #include <algorithm>
 #include <functional>
 #include <set>
 #include <vector>
@@ skipping 1625 matching lines @@
 AppCacheResponseReader* AppCacheStorageImpl::CreateResponseReader(
     const GURL& manifest_url, int64 group_id, int64 response_id) {
   return new AppCacheResponseReader(response_id, group_id, disk_cache());
 }
 
 AppCacheResponseWriter* AppCacheStorageImpl::CreateResponseWriter(
     const GURL& manifest_url, int64 group_id) {
   return new AppCacheResponseWriter(NewResponseId(), group_id, disk_cache());
 }
 
+AppCacheResponseMetadataWriter*
+AppCacheStorageImpl::CreateResponseMetadataWriter(int64 group_id,
+                                                  int64 response_id) {
+  return new AppCacheResponseMetadataWriter(response_id, group_id,
+                                            disk_cache());
+}
+
 void AppCacheStorageImpl::DoomResponses(
     const GURL& manifest_url, const std::vector<int64>& response_ids) {
   if (response_ids.empty())
     return;
 
   // Start deleting them from the disk cache lazily.
   StartDeletingResponses(response_ids);
 
   // Also schedule a database task to record these ids in the
   // deletable responses table.
@@ skipping 201 matching lines @@
       base::Bind(&AppCacheStorageImpl::CallScheduleReinitialize,
                  weak_factory_.GetWeakPtr()));
 }
 
 void AppCacheStorageImpl::CallScheduleReinitialize() {
   service_->ScheduleReinitialize();
   // note: 'this' may be deleted at this point.
 }
 
 }  // namespace content