Revert of webrtc: run tests in the checkout directory

scripts/slave/recipe_modules/webrtc/api.py

 # Copyright 2013 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.types import freeze
 from recipe_engine import recipe_api
 from . import builders
 from . import steps
 
 
@@ skipping 163 matching lines @@
       self.m.chromium.run_gn(use_goma=True)
 
     self.m.chromium.compile()
 
   def runtests(self):
     """Add a suite of test steps.
 
     Args:
       test_suite: The name of the test suite.
     """
-    with self.m.step.context({'cwd': self.m.path['checkout']}):
+    context = {}
+    if self._working_dir:
+      context['cwd'] = self._working_dir
+
+    with self.m.step.context(context):
       if self.c.use_isolate:
         self.m.isolate.remove_build_metadata()
         self.m.isolate.isolate_tests(self.m.chromium.output_dir,
                                      targets=self.NORMAL_TESTS)
 
       tests = steps.generate_tests(self, self.c.TEST_SUITE, self.revision,
                                    self.c.enable_swarming)
       with self.m.step.defer_results():
         if tests:
           if self.m.chromium.c.TARGET_PLATFORM == 'android':
@@ skipping 116 matching lines @@
   def clean_test_output(self):
     """Remove all test output in out/, since we have tests leaking files."""
     out_dir = self.m.path['checkout'].join('out')
     self.m.python('clean test output files',
                   script=self.resource('cleanup_files.py'),
                   args=[out_dir],
                   infra_step=True)
 
   def virtual_webcam_check(self):
     self.m.python('webcam_check', self.resource('ensure_webcam_is_running.py'))