WebRTC: Use custom mb_config_path for standalone bots.

scripts/slave/recipes/webrtc/ios.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 = [
   'depot_tools/bot_update',
   'depot_tools/gclient',
   'ios',
   'recipe_engine/path',
   'recipe_engine/platform',
@@ skipping 18 matching lines @@
   include_dir = api.path['checkout'].join(
       'webrtc',
       'build',
       'ios',
       'tests',
   )
   buildername = api.properties['buildername'].replace(' ', '_')
   api.ios.read_build_config(build_config_dir=build_config_dir,
                             include_dir=include_dir,
                             buildername=buildername)
-  api.ios.build()
+  mb_config_path = api.path['checkout'].join(
+      'webrtc',
+      'build',
+      'mb_config.pyl',
+  )
+  api.ios.build(mb_config_path=mb_config_path)
   api.ios.test()
 
 
 def GenTests(api):
   yield (
     api.test('basic')
     + api.platform('mac', 64)
     + api.properties(
       buildername='ios debug',
       buildnumber='0',
@@ skipping 19 matching lines @@
         {
           'app': 'fake tests 2',
           'device type': 'fake device',
           'os': '7.1',
         },
       ],
     })
   )
 
   yield (
+    api.test('gn_build')
+    + api.platform('mac', 64)
+    + api.properties(
+      buildername='ios',
+      buildnumber='0',
+      mastername='chromium.fake',
+      slavename='fake-vm',
+    )
+    + api.ios.make_test_build_config({
+      'xcode version': 'fake xcode version',
+      'GYP_DEFINES': {
+      },
+      "gn_args": [
+        "is_debug=true"
+      ],
+      "mb_type": "gn",
+      'compiler': 'ninja',
+      'configuration': 'Debug',
+      'sdk': 'iphoneos8.0',
+      'tests': [
+      ],
+    })
+  )
+
+  yield (
     api.test('no_tests')
     + api.platform('mac', 64)
     + api.properties(
       buildername='ios',
       buildnumber='0',
       mastername='chromium.fake',
       slavename='fake-vm',
     )
     + api.ios.make_test_build_config({
       'xcode version': 'fake xcode version',
@@ skipping 103 matching lines @@
           'os': '7.1',
         },
       ],
     })
     + api.step_data(
       'fake tests 1 (fake device iOS 8.0)',
       retcode=2,
     )
   )