Add a check that the Chromedriver prebuilt name is expected.

scripts/slave/recipe_modules/chromedriver/example.py

 # Copyright 2016 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.
 
 from recipe_engine import recipe_api
 from recipe_engine.types import freeze
 
 DEPS = [
   'archive',
   'chromedriver',
   'chromium',
   'chromium_android',
   'commit_position',
   'depot_tools/bot_update',
   'depot_tools/gclient',
+  'recipe_engine/json',
   'recipe_engine/platform',
   'recipe_engine/properties',
   'recipe_engine/raw_io',
   'recipe_engine/step',
 ]
 
 BUILDERS = freeze({
   'Android ChromeDriver Tests Example': {
     'chromedriver_platform': 'android',
     # Whether or not to update the test results log (Android only).
@@ skipping 73 matching lines @@
   yield (
       api.test('%s_download_logs_failure' % sanitize('Android ChromeDriver')) +
       api.properties.generic(
           buildername='Android ChromeDriver Tests Example',
           slavename='slavename') +
       api.properties(
           parent_build_archive_url='gs://test-domain/test-archive.zip',
           got_revision_cp='refs/heads/master@{#3333333333}') +
       api.step_data(
           'Download Test Results Log.gsutil download results log', retcode=1))
+
+  yield (
+      api.test('%s_unexpected_prebuilt' % sanitize('Android ChromeDriver')) +
+      api.properties.generic(
+          buildername='Android ChromeDriver Tests Example',
+          slavename='slavename') +
+      api.properties(
+          parent_build_archive_url='gs://test-domain/test-archive.zip',
+          got_revision_cp='refs/heads/master@{#3333333333}') +
+      api.step_data(
+          'Download Prebuilts.listdir get prebuilt filename',
+          api.json.output(['rNone.zip'])))