Workaround for a crashing appcache bug seen on the crash servers

webkit/appcache/appcache_update_job.h

 // 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.
 
 #ifndef WEBKIT_APPCACHE_APPCACHE_UPDATE_JOB_H_
 #define WEBKIT_APPCACHE_APPCACHE_UPDATE_JOB_H_
 
 #include <deque>
 #include <map>
 #include <set>
@@ skipping 217 matching lines @@
   void ClearPendingMasterEntries();
   void DiscardInprogressCache();
   void DiscardDuplicateResponses();
 
   // Deletes this object after letting the stack unwind.
   void DeleteSoon();
 
   bool IsTerminating() { return internal_state_ >= REFETCH_MANIFEST ||
                                 stored_state_ != UNSTORED; }
 
-  GURL manifest_url_;  // here for easier access
   AppCacheService* service_;
+  const GURL manifest_url_;  // here for easier access
 
   scoped_refptr<AppCache> inprogress_cache_;
 
   AppCacheGroup* group_;
 
   UpdateType update_type_;
   InternalUpdateState internal_state_;
 
   PendingMasters pending_master_entries_;
   size_t master_entries_completed_;
@@ skipping 50 matching lines @@
   StoredState stored_state_;
 
   FRIEND_TEST_ALL_PREFIXES(AppCacheGroupTest, QueueUpdate);
 
   DISALLOW_COPY_AND_ASSIGN(AppCacheUpdateJob);
 };
 
 }  // namespace appcache
 
 #endif  // WEBKIT_APPCACHE_APPCACHE_UPDATE_JOB_H_