Add kiosk enterprise enrollment test.

Test to enrollment the device in kiosk mode. This test relies on kiosk
app attributes including name and extension id which are provided via
the server side control file as well as login credentials for each
different kiosk app. These credentials are stored in
credentials.<app_name> file next to the enterprise_KioskEnrollment.py.
By default if no kiosk app attributes are provide, the device will
enroll using the default credentials in credentials.chromesign.

BUG=None
TEST=Locally

Change-Id: Ic0b2df9f95ff3467618f79f728425e0993c49d8a
Reviewed-on: https://chromium-review.googlesource.com/352245
Commit-Ready: Harpreet Grewal <harpreet@chromium.org>
Tested-by: Harpreet Grewal <harpreet@chromium.org>
Reviewed-by: Kalin Stoyanov <kalin@chromium.org>
diff --git a/client/common_lib/cros/enrollment.py b/client/common_lib/cros/enrollment.py
index 66f112a..883706d 100644
--- a/client/common_lib/cros/enrollment.py
+++ b/client/common_lib/cros/enrollment.py
@@ -38,3 +38,16 @@
             lambda: browser.oobe.NavigateGaiaLogin(
                     user_id, password, enterprise_enroll=True,
                     for_user_triggered_enrollment=False))
+
+
+def EnterpriseEnrollment(browser, user_id, password):
+    """Enterprise login for a kiosk device.
+
+    @param browser: telemetry browser object.
+    @param user_id: login credentials user_id.
+    @param password: login credentials password.
+    """
+    chrome.Chrome.wait_for_browser_restart(
+            lambda: browser.oobe.NavigateGaiaLogin(
+                    user_id, password, enterprise_enroll=True,
+                    for_user_triggered_enrollment=True))