Refactor kiosk app launch to be part of login screen UI flow.

chrome/browser/chromeos/app_mode/app_launch_utils.h

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_CHROMEOS_APP_MODE_APP_LAUNCH_UTILS_H_
+#define CHROME_BROWSER_CHROMEOS_APP_MODE_APP_LAUNCH_UTILS_H_
+
+#include <string>
+
+class Profile;
+
+namespace chromeos {
+
+// Attempts to launch the app given by |app_id| in app mode
+// or exit on failure. This function will not show any launch UI
+// during the launch. Use StartupAppLauncher for finer control
+// over the app launch processes.
+void LaunchAppOrDie(Profile *profile, const std::string& app_id);
+
+}  // namespace chromeos
+
+#endif // CHROME_BROWSER_CHROMEOS_APP_MODE_APP_LAUNCH_UTILS_H_