Introduce AppCacheResponseMetadataWriter to support metadata caching.

content/browser/appcache/appcache_storage_impl.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.
 
 #ifndef CONTENT_BROWSER_APPCACHE_APPCACHE_STORAGE_IMPL_H_
 #define CONTENT_BROWSER_APPCACHE_APPCACHE_STORAGE_IMPL_H_
 
 #include <deque>
 #include <map>
 #include <set>
@@ skipping 46 matching lines @@
                                  bool* found_network_namespace) override;
   void MarkEntryAsForeign(const GURL& entry_url, int64 cache_id) override;
   void MakeGroupObsolete(AppCacheGroup* group,
                          Delegate* delegate,
                          int response_code) override;
   AppCacheResponseReader* CreateResponseReader(const GURL& manifest_url,
                                                int64 group_id,
                                                int64 response_id) override;
   AppCacheResponseWriter* CreateResponseWriter(const GURL& manifest_url,
                                                int64 group_id) override;
+  AppCacheResponseMetadataWriter* CreateResponseMetadataWriter(
+      int64 group_id,
+      int64 response_id) override;
   void DoomResponses(const GURL& manifest_url,
                      const std::vector<int64>& response_ids) override;
   void DeleteResponses(const GURL& manifest_url,
                        const std::vector<int64>& response_ids) override;
 
  private:
   // The AppCacheStorageImpl class methods and datamembers may only be
   // accessed on the IO thread. This class manufactures seperate DatabaseTasks
   // which access the DB on a seperate background thread.
   class DatabaseTask;
@@ skipping 97 matching lines @@
   std::deque<base::Closure> pending_simple_tasks_;
   base::WeakPtrFactory<AppCacheStorageImpl> weak_factory_;
 
   friend class content::AppCacheStorageImplTest;
   friend class content::ChromeAppCacheServiceTest;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_APPCACHE_APPCACHE_STORAGE_IMPL_H_