timezone match code - consider canonical id as well

chromeos/settings/timezone_settings_helper.h

+// Copyright 2015 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 CHROMEOS_SETTINGS_TIMEZONE_SETTINGS_HELPER_H_
+#define CHROMEOS_SETTINGS_TIMEZONE_SETTINGS_HELPER_H_
+
+#include <vector>
+
+#include "third_party/icu/source/i18n/unicode/timezone.h"
+
+namespace chromeos {
+namespace system {
+
+// Return a timezone in the list matching |timezone| in terms of
+// id and canonical id. If both fail, return a timezone with
+// the same rules. Otherwise, return null.
+const icu::TimeZone* GetKnownTimezoneOrNull(
+    const icu::TimeZone& timezone,
+    const std::vector<icu::TimeZone*>& timezone_list);
+
+}  // namespace system
+}  // namespace chromeos
+
+#endif  // CHROMEOS_SETTINGS_TIMEZONE_SETTINGS_HELPER_H_