Add swarming support for MB (and the GN bots) in the chromium recipes.

scripts/slave/recipe_modules/chromium_tests/api.py

 # Copyright 2014 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.
 
 import contextlib
 import copy
 import json
 
 from infra.libs.infra_types import freeze, thaw
 from recipe_engine import recipe_api
@@ skipping 89 matching lines @@
         except self.m.step.StepFailure:
           # As part of deapplying patch we call runhooks without the patch.
           self.deapply_patch(update_step)
           raise
       else:
         self.m.chromium.runhooks()
 
     test_spec_file = bot_config.get('testing', {}).get('test_spec_file',
                                                        '%s.json' % mastername)
 
-    if self.m.chromium.c.project_generator.tool == 'mb':
-      self.m.chromium.run_mb(mastername, buildername)
-
     # TODO(phajdan.jr): Bots should have no generators instead.
     if bot_config.get('disable_tests'):
       test_spec = {}
       scripts_compile_targets = {}
     else:
       test_spec = self.read_test_spec(self.m, test_spec_file)
       test_spec_path = self.m.path['checkout'].join('testing', 'buildbot',
                                                  test_spec_file)
 
       scripts_compile_targets = \
@@ skipping 488 matching lines @@
           master_config.get('build_gs_bucket'),
           extra_url_components=None)
     elif (mastername == 'tryserver.chromium.perf' or
           (mastername == 'tryserver.chromium.linux' and
            buildername == 'linux_full_bisect_builder')):
       return None
     else:
       return self.m.archive.legacy_upload_url(
           master_config.get('build_gs_bucket'),
           extra_url_components=self.m.properties['mastername'])