Update from https://crrev.com/327068

mojo/tools/mopy/gn_unittest.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 itertools
 import sys
 import unittest
 
 import mopy.gn as gn
 
@@ skipping 19 matching lines @@
 
     for args in _iterate_over_config(configs_to_test):
       config = Config(**args)
       gn_args = gn.GNArgsForConfig(config)
       new_config = gn.ConfigForGNArgs(gn_args)
       self.assertDictEqual(config.values, new_config.values)
 
   def testGNToConfigToGN(self):
     """Tests that gn to config to gn is the identity"""
     configs_to_test = {
-      "os": [None, "android", "chromeos"],
+      "target_os": [None, "android", "chromeos"],
       "target_cpu": ["x86", "x64", "arm"],
       "is_debug": [False, True],
       "is_clang": [False, True],
       "is_asan": [False, True],
       "use_goma": [False],
       "mojo_use_nacl": [False, True],
       "mojo_use_go": [False],
       "dcheck_always_on": [False, True],
     }
 
     for args in _iterate_over_config(configs_to_test):
-      if args.get('os', None) == "chromeos":
-        args['use_glib'] = False
-        args['use_system_harfbuzz'] = False
-      if args.get('os', None) is None and sys.platform[:5] == 'linux':
+      if args.get("target_os", None) == "chromeos":
+        args["use_glib"] = False
+        args["use_system_harfbuzz"] = False
+      if args.get("target_os", None) is None and sys.platform[:5] == "linux":
         args["use_aura"] = False
         args["use_glib"] = False
         args["use_system_harfbuzz"] = False
       config = gn.ConfigForGNArgs(args)
       new_args = gn.GNArgsForConfig(config)
       self.assertDictEqual(args, new_args)
 
 
 def _iterate_over_config(config):
   def product_to_dict(p):
     return dict(filter(lambda x: x[1] is not None, zip(config.keys(), p)))
   return itertools.imap(product_to_dict, itertools.product(*config.values()))
 
 
 if __name__ == "__main__":
   unittest.main()