sync: Store hard coded constants into its header file.

chrome/browser/sync/tools/sync_constants.h

Index: chrome/browser/sync/tools/sync_constants.h
diff --git a/chrome/browser/sync/tools/sync_constants.h b/chrome/browser/sync/tools/sync_constants.h
new file mode 100644
index 0000000000000000000000000000000000000000..a80cc3d9ad4059cb3cb26a3db51b443e57537469
--- /dev/null
+++ b/chrome/browser/sync/tools/sync_constants.h
@@ -0,0 +1,17 @@
+// 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_TOOLS_SYNC_CONSTANTS_H_
+#define CHROME_BROWSER_SYNC_TOOLS_SYNC_CONSTANTS_H_
+
+namespace sync_tools {
+
+extern const char kAutoFillType[];
+extern const char kBookmarkType[];
+extern const char kPreferenceType[];
+extern const char kThemeType[];
+
+}  // namespace sync_tools
+
+#endif  // CHROME_BROWSER_SYNC_TOOLS_SYNC_CONSTANTS_H_