Add ARC++ kiosk menu items and ability to start kiosk session.

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

Index: chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
index 0129aeed3da9a75b5e3c50df87cc3894098fef8e..cfe9d8c109321fb9bf724fb6f6c9ea490af428b0 100644
--- a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
@@ -559,6 +559,8 @@ void SigninScreenHandler::RegisterMessages() {
   // This message is sent by the kiosk app menu, but is handled here
   // so we can tell the delegate to launch the app.
   AddCallback("launchKioskApp", &SigninScreenHandler::HandleLaunchKioskApp);
+  AddCallback("launchArcKioskApp",
+              &SigninScreenHandler::HandleLaunchArcKioskApp);
 }
 
 void SigninScreenHandler::Show(const LoginScreenContext& context) {
@@ -1385,6 +1387,13 @@ void SigninScreenHandler::HandleLaunchKioskApp(const AccountId& app_account_id,
     delegate_->Login(context, specifics);
 }
 
+void SigninScreenHandler::HandleLaunchArcKioskApp(
+    const AccountId& app_account_id) {
+  UserContext context(user_manager::USER_TYPE_ARC_KIOSK_APP, app_account_id);
+  if (delegate_)
+    delegate_->Login(context, SigninSpecifics());
+}
+
 void SigninScreenHandler::HandleGetTouchViewState() {
   if (max_mode_delegate_) {
     CallJS("login.AccountPickerScreen.setTouchViewState",