oobe: Check if WizardController is initialized for testing methods

This CL fixes regression introduces in CL:2230472. Before *ForTesting
methods checked if WC is created. After the offending CL WC is always
created. So in this CL the methods also check if the WC is initialized

Bug: 1094552
Change-Id: I603de486c6da5e62a406c7f6ecd407dafabf7762
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2247734
Auto-Submit: Roman Sorokin [CET] <rsorokin@chromium.org>
Commit-Queue: Denis Kuznetsov [CET] <antrim@chromium.org>
Reviewed-by: Denis Kuznetsov [CET] <antrim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#779321}

chrome/browser/ui/webui/chromeos/login/core_oobe_handler.cc

@@ -376,13 +376,15 @@ void CoreOobeHandler::HandleSetDeviceRequisition(
 }
 
 void CoreOobeHandler::HandleSkipToLoginForTesting() {
-  if (WizardController::default_controller())
+  WizardController* controller = WizardController::default_controller();
+  if (controller && controller->is_initialized())
     WizardController::default_controller()->SkipToLoginForTesting();
 }
 
 void CoreOobeHandler::HandleSkipToUpdateForTesting() {
-  if (WizardController::default_controller())
-    WizardController::default_controller()->SkipToUpdateForTesting();
+  WizardController* controller = WizardController::default_controller();
+  if (controller && controller->is_initialized())
+    controller->SkipToUpdateForTesting();
 }
 
 void CoreOobeHandler::HandleToggleResetScreen() {