Change how MB handles goma_dir.

tools/mb/mb_unittest.py

 #!/usr/bin/python
 # Copyright 2015 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.
 
 """Tests for mb.py."""
 
 import json
 import StringIO
 import os
@@ skipping 113 matching lines @@
     'crosscompile': {
       'gyp_crosscompile': True,
     },
     'fake_feature1': {
       'gn_args': 'enable_doom_melon=true',
       'gyp_defines': 'doom_melon=1',
     },
     'gyp': {'type': 'gyp'},
     'gn': {'type': 'gn'},
     'goma': {
-      'gn_args': 'use_goma=true goma_dir="$(goma_dir)"',
-      'gyp_defines': 'goma=1 gomadir=$(goma_dir)',
+      'gn_args': 'use_goma=true',
+      'gyp_defines': 'goma=1',
     },
     'rel': {
       'gn_args': 'is_debug=false',
     },
     'debug': {
       'gn_args': 'is_debug=true',
     },
   },
 }
 """
@@ skipping 295 matching lines @@
     self.check(['validate'], mbw=mbw, ret=0)
 
   def test_bad_validate(self):
     mbw = self.fake_mbw()
     mbw.files[mbw.default_config] = TEST_BAD_CONFIG
     self.check(['validate'], mbw=mbw, ret=1)
 
 
 if __name__ == '__main__':
   unittest.main()