[Sync] Split DirectoryChangeListener for thread-safety

chrome/test/sync/null_directory_change_delegate.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/test/sync/null_directory_change_delegate.h"
+
+namespace syncable {
+
+NullDirectoryChangeDelegate::~NullDirectoryChangeDelegate() {}
+
+void NullDirectoryChangeDelegate::HandleCalculateChangesChangeEventFromSyncApi(
+    const OriginalEntries& originals,
+    BaseTransaction* trans) {}
+
+void NullDirectoryChangeDelegate::HandleCalculateChangesChangeEventFromSyncer(
+    const OriginalEntries& originals,
+    BaseTransaction* trans) {}
+
+ModelTypeBitSet NullDirectoryChangeDelegate::HandleTransactionEndingChangeEvent(
+      BaseTransaction* trans) {
+  return ModelTypeBitSet();
+}
+
+void NullDirectoryChangeDelegate::HandleTransactionCompleteChangeEvent(
+    const ModelTypeBitSet& models_with_changes) {}
+
+}  // namespace syncable