Drop unwanted dependencies on chromium_tests recipe module

scripts/slave/recipes/webrtc/ios_api_framework.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.
 
 DEPS = [
   'archive',
-  'chromium_tests',
+  'chromium_checkout',
   'commit_position',
   'depot_tools/bot_update',
   'depot_tools/gclient',
   'depot_tools/tryserver',
   'file',
   'gsutil',
   'ios',
   'recipe_engine/path',
   'recipe_engine/properties',
   'recipe_engine/step',
   'webrtc',
   'zip',
 ]
 
 
 def RunSteps(api):
   api.gclient.set_config('webrtc_ios')
 
   api.ios.host_info()
 
   checkout_kwargs = {}
-  checkout_dir = api.chromium_tests.get_checkout_dir({})
+  checkout_dir = api.chromium_checkout.get_checkout_dir({})
   if checkout_dir:
     checkout_kwargs['cwd'] = checkout_dir
   update_step = api.bot_update.ensure_checkout(**checkout_kwargs)
 
   revs = update_step.presentation.properties
   commit_pos = api.commit_position.parse_revision(revs['got_revision_cp'])
   api.gclient.runhooks()
 
   build_script = api.path['checkout'].join('webrtc', 'build', 'ios',
                                            'build_ios_libs.sh')
@@ skipping 34 matching lines @@
                            path_config='kitchen') +
     api.step_data('build', retcode=1)
   )
 
   yield (
     api.test('trybot_build') +
     api.properties.tryserver(mastername='tryserver.webrtc',
                              buildername='ios_api_framework',
                              path_config='kitchen')
   )