ChromeOS: implement per-user time zone preferences.

chrome/browser/chromeos/system/timezone_util.h

Index: chrome/browser/chromeos/system/timezone_util.h
diff --git a/chrome/browser/chromeos/system/timezone_util.h b/chrome/browser/chromeos/system/timezone_util.h
index 92d8ade532b481f18f53969043bccfbd21d97e9c..f4cef6a064fd4d4e11d6f5490392b15e60f1fa46 100644
--- a/chrome/browser/chromeos/system/timezone_util.h
+++ b/chrome/browser/chromeos/system/timezone_util.h
@@ -9,6 +9,8 @@
 
 #include "base/strings/string16.h"
 
+class Profile;
+
 namespace base {
 class ListValue;
 }
@@ -31,6 +33,21 @@ bool HasSystemTimezonePolicy();
 // Apply TimeZone update from TimeZoneProvider.
 void ApplyTimeZone(const TimeZoneResponseData* timezone);
 
+// Returns true if given timezone preference is enterprise-managed.
+// Works for:
+// - prefs::kUserTimezone
+// - prefs::kResolveTimezoneByGeolocation
+bool IsTimezonePrefsManaged(const std::string& pref_name);
+
+// Updates system timezone from user profile data if needed.
+void UpdateSystemTimezone(Profile* profile);
+
+// Updates Local State preference prefs::kSigninScreenTimezone.
+// If |set_system_timezone|, chromeos::system::TimezoneSettings will also
+// be updated.
+void SetSigninScreenTimezone(const std::string& timezone,
+                             bool set_system_timezone);
+
 }  // namespace system
 }  // namespace chromeos