Fix deps_updater.py to use 'origin/master' instead of 'master'

third_party/WebKit/Tools/Scripts/webkitpy/w3c/deps_updater.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.
 
 """Fetches a copy of the latest state of a W3C test repository and commits.
 
 If this script is given the argument --auto-update, it will also attempt to
 upload a CL, triggery try jobs, and make any changes that are required for
 new failing tests before committing.
 """
@@ skipping 280 matching lines @@
             return False
         return True
 
     def get_directory_owners_to_cc(self):
         """Returns a list of email addresses to CC for the current import."""
         self.print_('## Gathering directory owners emails to CC.')
         directory_owners_file_path = self.finder.path_from_webkit_base(
             'Tools', 'Scripts', 'webkitpy', 'w3c', 'directory_owners.json')
         with open(directory_owners_file_path) as data_file:
             directory_to_owner = self.parse_directory_owners(json.load(data_file))
-        out = self.check_run(['git', 'diff', 'master', '--name-only'])
+        out = self.check_run(['git', 'diff', 'origin/master', '--name-only'])
         changed_files = out.splitlines()
         return self.generate_email_list(changed_files, directory_to_owner)
 
     @staticmethod
     def parse_directory_owners(decoded_data_file):
         directory_dict = {}
         for dict_set in decoded_data_file:
             if dict_set['notification-email']:
                 directory_dict[dict_set['directory']] = dict_set['notification-email']
         return directory_dict
@@ skipping 20 matching lines @@
                 email_addresses.add(directory_to_owner[test_dir])
         return sorted(email_addresses)
 
     def write_test_expectations(self):
         self.print_('## Adding test expectations lines to LayoutTests/TestExpectations.')
         script_path = self.path_from_webkit_base('Tools', 'Scripts', 'update-w3c-test-expectations')
         self.run([self.host.executable, script_path])
         message = '\'Modifies TestExpectations and/or downloads new baselines for tests\''
         self.check_run(['git', 'commit', '-a', '-m', message])
         self.git_cl(['upload', '-m', message, '--rietveld'])