[sync] Add backup time in synced device info so that server can flag device

sync/internal_api/public/util/sync_db_util.h

Index: sync/internal_api/public/util/sync_db_util.h
diff --git a/sync/internal_api/public/util/sync_db_util.h b/sync/internal_api/public/util/sync_db_util.h
new file mode 100644
index 0000000000000000000000000000000000000000..3784a10f2f1b173ce98fb25f9164974c70ca7327
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+++ b/sync/internal_api/public/util/sync_db_util.h
@@ -0,0 +1,30 @@
+// Copyright 2014 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 SYNC_INTERNAL_API_PUBLIC_UTIL_SYNC_DB_UTIL_H_
+#define SYNC_INTERNAL_API_PUBLIC_UTIL_SYNC_DB_UTIL_H_
+
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/time/time.h"
+#include "sync/base/sync_export.h"
+
+namespace base {
+class FilePath;
+class SingleThreadTaskRunner;
+}  // namespace base
+
+namespace syncer {
+
+// Check integrity of sync DB under |sync_dir|. Invoke |callback| with last
+// modified time if integrity check passes, with NULL time otherwise. This
+// is called on either sync thread or IO thread.
+SYNC_EXPORT void CheckSyncDbLastModifiedTime(
+    const base::FilePath& sync_dir,
+    scoped_refptr<base::SingleThreadTaskRunner> callback_runner,
+    base::Callback<void(base::Time)> callback);
+
+}  // namesapce syncer
+
+#endif  // SYNC_INTERNAL_API_PUBLIC_UTIL_SYNC_DB_UTIL_H_