Speculative fix for build on windows build bots.

recipes/blink.py

 # Copyright (c) 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.
 
 import json
 import sys
 
 import recipe_util  # pylint: disable=F0401
 
 
@@ skipping 12 matching lines @@
     return {
       'alias': {
         'recipe': 'chromium',
         'props': [
           '--webkit_revision=ToT',
           '--submodule_git_svn_spec=' + json.dumps(submodule_spec),
         ],
       },
     }
 
+  @staticmethod
+  def expected_root(_props):
+    return ''
+
 
 def main(argv=None):
   return Blink().handle_args(argv)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))