[Sync] Split DirectoryChangeListener for thread-safety

chrome/browser/sync/engine/process_updates_command.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 "chrome/browser/sync/engine/process_updates_command.h"
 
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/tracked.h"
 #include "chrome/browser/sync/engine/syncer.h"
 #include "chrome/browser/sync/engine/syncer_proto_util.h"
 #include "chrome/browser/sync/engine/syncer_util.h"
 #include "chrome/browser/sync/engine/syncproto.h"
 #include "chrome/browser/sync/sessions/sync_session.h"
 #include "chrome/browser/sync/syncable/directory_manager.h"
 #include "chrome/browser/sync/syncable/syncable.h"
 
 using std::vector;
 
@@ skipping 70 matching lines @@
 
 // Process a single update. Will avoid touching global state.
 ServerUpdateProcessingResult ProcessUpdatesCommand::ProcessUpdate(
     const syncable::ScopedDirLookup& dir,
     const sync_pb::SyncEntity& proto_update) {
 
   const SyncEntity& update = *static_cast<const SyncEntity*>(&proto_update);
   syncable::Id server_id = update.id();
   const std::string name = SyncerProtoUtil::NameFromSyncEntity(update);
 
-  syncable::WriteTransaction trans(dir, syncable::SYNCER, __FILE__, __LINE__);
+  syncable::WriteTransaction trans(dir, syncable::SYNCER, FROM_HERE);
 
   // Look to see if there's a local item that should recieve this update,
   // maybe due to a duplicate client tag or a lost commit response.
   syncable::Id local_id = SyncerUtil::FindLocalIdToUpdate(&trans, update);
 
   // FindLocalEntryToUpdate has veto power.
   if (local_id.IsNull()) {
     return SUCCESS_PROCESSED;  // The entry has become irrelevant.
   }
 
@@ skipping 44 matching lines @@
     // If these don't match, it means that we have a different view of the
     // truth from other clients.  That's a sync bug, though we may be able
     // to recover the next time this item commits.
     LOG_IF(ERROR, !SyncerUtil::ServerAndLocalEntriesMatch(&target_entry))
         << target_entry;
   }
   return SUCCESS_PROCESSED;
 }
 
 }  // namespace browser_sync