Handle Smart Lock for Android promotion screen.

components/proximity_auth/e2e_test/setup_test.py

 # Copyright 2015 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.
 
 """ Script that exercises the Smart Lock setup flow, testing that a nearby phone
 can be found and used to unlock a Chromebook.
 
 Note: This script does not currently automate Android phones, so make sure that
 a phone is properly configured and online before starting the test.
 
@@ skipping 134 matching lines @@
     logger.info('Opening Smart Lock settings...')
     settings = chromeos.GetSmartLockSettings()
     assert(not settings.is_smart_lock_enabled)
 
     if args.cryptauth_staging_url is not None:
       chromeos.SetCryptAuthStaging(args.cryptauth_staging_url)
 
     logger.info('Starting Smart Lock setup flow...')
     app = settings.StartSetupAndReturnApp()
 
+    if app is None:
+      raise SmartLockSetupError('Failed to obtain set up app window')
+
     _NavigateSetupDialog(chromeos, app)
 
 def main():
   logging.basicConfig()
   logging.getLogger('proximity_auth').setLevel(logging.INFO)
   args = ParseArgs()
   RunSetupTest(args)
 
 if __name__ == '__main__':
   main()