sync: beginnings of MessageLoop based SyncerThread

chrome/browser/sync/engine/nudge_source.h

+// Copyright (c) 2010 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 CHROME_BROWSER_SYNC_ENGINE_NUDGE_SOURCE_H_
+#define CHROME_BROWSER_SYNC_ENGINE_NUDGE_SOURCE_H_
+#pragma once
+
+namespace browser_sync {
+
+namespace s3 {
+
+enum NudgeSource {
+  NUDGE_SOURCE_UNKNOWN = 0,
+  // We received an invalidation message and are nudging to check for updates.
+  NUDGE_SOURCE_NOTIFICATION,
+  // A local change occurred (e.g. bookmark moved).
+  NUDGE_SOURCE_LOCAL,
+  // A previous sync cycle did not fully complete (e.g. HTTP error).
+  NUDGE_SOURCE_CONTINUATION,
+  // A nudge corresponding to the user invoking a function in the UI to clear
+  // their entire account and stop syncing (globally).
+  NUDGE_SOURCE_CLEAR_PRIVATE_DATA,
+};
+
+}  // namespace s3
+}  // namespace browser_sync
+
+#endif  // CHROME_BROWSER_SYNC_ENGINE_NUDGE_SOURCE_H_