[Kiosk] Initialize CrOS prefs and keyboard for arc kiosk

During profile initialization, we have do a early exit for all kiosk
types. Every kiosk separately inits CrOS prefs and keyboardcontroller,
but ArcKiosk. This CL fixes that.

Bug: 1040742, 1040744
Change-Id: Ic140d76fd12182dccd6decc239787e812abd1686
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2011100Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Anatoliy Potapchuk <apotapchuk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#733931}

chrome/browser/chromeos/login/arc_kiosk_controller.cc

@@ -140,6 +140,13 @@ void ArcKioskController::OnProfilePrepared(Profile* profile,
   // a profile load, so invalidate the delegate now.
   UserSessionManager::GetInstance()->DelegateDeleted(this);
   ArcKioskAppService::Get(profile_)->SetDelegate(this);
+
+  // This is needed to trigger input method extensions being loaded.
+  profile->InitChromeOSPreferences();
+
+  // Reset virtual keyboard to use IME engines in app profile early.
+  ChromeKeyboardControllerClient::Get()->RebuildKeyboardIfEnabled();
+
   if (arc_kiosk_splash_screen_view_) {
     arc_kiosk_splash_screen_view_->UpdateArcKioskState(
         ArcKioskSplashScreenView::ArcKioskState::WAITING_APP_LAUNCH);