ChromeOS: implement per-user time zone preferences.

chrome/browser/chromeos/login/ui/login_display_host_impl.cc

Index: chrome/browser/chromeos/login/ui/login_display_host_impl.cc
diff --git a/chrome/browser/chromeos/login/ui/login_display_host_impl.cc b/chrome/browser/chromeos/login/ui/login_display_host_impl.cc
index 6db2b1af8b0e70bb4d47adbe482ba8dd6dcb53d3..cd541a7a09d46243c4124832c272bf77436a31a2 100644
--- a/chrome/browser/chromeos/login/ui/login_display_host_impl.cc
+++ b/chrome/browser/chromeos/login/ui/login_display_host_impl.cc
@@ -189,20 +189,26 @@ void ShowLoginWizardFinish(
     chromeos::LoginDisplayHost* display_host) {
   TRACE_EVENT0("chromeos", "ShowLoginWizard::ShowLoginWizardFinish");
 
+  // Restore system timezone.
+  std::string timezone;
+  timezone =
+      g_browser_process->local_state()->GetString(prefs::kSigninScreenTimezone);
+
   if (ShouldShowSigninScreen(first_screen)) {
     display_host->StartSignInScreen(chromeos::LoginScreenContext());
   } else {
     display_host->StartWizard(first_screen);
-
     // Set initial timezone if specified by customization.
-    const std::string timezone_name = startup_manifest->initial_timezone();
-    VLOG(1) << "Initial time zone: " << timezone_name;
+    const std::string customization_timezone =
+        startup_manifest->initial_timezone();
     // Apply locale customizations only once to preserve whatever locale
     // user has changed to during OOBE.
-    if (!timezone_name.empty()) {
-      chromeos::system::TimezoneSettings::GetInstance()->SetTimezoneFromID(
-          base::UTF8ToUTF16(timezone_name));
-    }
+    if (!customization_timezone.empty())
+      timezone = customization_timezone;
+  }
+  if (!timezone.empty()) {
+    chromeos::system::SetSigninScreenTimezone(timezone,
+                                              true /* set_system_timezone */);
   }
 }