[Sync] Split DirectoryChangeListener for thread-safety

chrome/browser/sync/engine/apply_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/apply_updates_command.h"
 
+#include "base/tracked.h"
 #include "chrome/browser/sync/engine/update_applicator.h"
 #include "chrome/browser/sync/sessions/sync_session.h"
 #include "chrome/browser/sync/syncable/directory_manager.h"
 #include "chrome/browser/sync/syncable/syncable.h"
 
 namespace browser_sync {
 
 using sessions::SyncSession;
 
 ApplyUpdatesCommand::ApplyUpdatesCommand() {}
 ApplyUpdatesCommand::~ApplyUpdatesCommand() {}
 
 void ApplyUpdatesCommand::ModelChangingExecuteImpl(SyncSession* session) {
   syncable::ScopedDirLookup dir(session->context()->directory_manager(),
                                 session->context()->account_name());
   if (!dir.good()) {
     LOG(ERROR) << "Scoped dir lookup failed!";
     return;
   }
-  syncable::WriteTransaction trans(dir, syncable::SYNCER, __FILE__, __LINE__);
+  syncable::WriteTransaction trans(dir, syncable::SYNCER, FROM_HERE);
   syncable::Directory::UnappliedUpdateMetaHandles handles;
   dir->GetUnappliedUpdateMetaHandles(&trans, &handles);
 
   UpdateApplicator applicator(
       session->context()->resolver(),
       session->context()->directory_manager()->GetCryptographer(&trans),
       handles.begin(), handles.end(), session->routing_info(),
       session->status_controller()->group_restriction());
   while (applicator.AttemptOneApplication(&trans)) {}
   applicator.SaveProgressIntoSessionState(
@@ skipping 16 matching lines @@
       syncable::ModelType model_type = syncable::ModelTypeFromInt(i);
       if (status->updates_request_types()[i]) {
         // This gets persisted to the directory's backing store.
         dir->set_initial_sync_ended_for_type(model_type, true);
       }
     }
   }
 }
 
 }  // namespace browser_sync