sync: remove use of protobuf extensions in protocol to reduce static init overhead.

chrome/browser/sync/syncable/directory_backing_store.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 "chrome/browser/sync/syncable/directory_backing_store.h"
 
 #include "build/build_config.h"
 
 #include <limits>
 
@@ skipping 662 matching lines @@
                                  sync_pb::EntitySpecifics* mutable_new_value) {
   // Extract data from the column trio we expect.
   bool old_is_bookmark_object = old_value_query->ColumnBool(old_value_column);
   std::string old_url = old_value_query->ColumnString(old_value_column + 1);
   std::string old_favicon;
   old_value_query->ColumnBlobAsString(old_value_column + 2, &old_favicon);
   bool old_is_dir = old_value_query->ColumnBool(old_value_column + 3);
 
   if (old_is_bookmark_object) {
     sync_pb::BookmarkSpecifics* bookmark_data =
-        mutable_new_value->MutableExtension(sync_pb::bookmark);
+        mutable_new_value->mutable_bookmark();
     if (!old_is_dir) {
       bookmark_data->set_url(old_url);
       bookmark_data->set_favicon(old_favicon);
     }
   }
 }
 
 }  // namespace
 
 bool DirectoryBackingStore::MigrateVersion68To69() {
@@ skipping 398 matching lines @@
       "id TEXT primary key, "
       "name TEXT, "
       "store_birthday TEXT, "
       "db_create_version TEXT, "
       "db_create_time INT, "
       "next_id INT default -2, "
       "cache_guid TEXT )");
   return db_.Execute(query.c_str());
 }
 }  // namespace syncable