Add Store+Sync to reading list.

ios/chrome/browser/reading_list/reading_list_pref_names.h

Index: ios/chrome/browser/reading_list/reading_list_pref_names.h
diff --git a/ios/chrome/browser/reading_list/reading_list_pref_names.h b/ios/chrome/browser/reading_list/reading_list_pref_names.h
new file mode 100644
index 0000000000000000000000000000000000000000..9a0069305b1c273610dffc63ba40a34c6898f40d
--- /dev/null
+++ b/ios/chrome/browser/reading_list/reading_list_pref_names.h
@@ -0,0 +1,18 @@
+// Copyright 2016 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.
+
+// Constants for the names of various reading list preferences.
+
+#ifndef IOS_CHROME_BROWSER_READING_LIST_READING_LIST_PREF_NAMES_H_
+#define IOS_CHROME_BROWSER_READING_LIST_READING_LIST_PREF_NAMES_H_
+
+namespace reading_list {
+namespace prefs {
+
+extern const char kReadingListHasUnseenEntries[];
+
+}  // namespace prefs
+}  // namespace reading_list
+
+#endif  // IOS_CHROME_BROWSER_READING_LIST_READING_LIST_PREF_NAMES_H_