[Android] Fix new pylint errors in build/android/.

build/android/pylib/utils/report_results.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.
 
 """Module containing utility functions for reporting results."""
 
 import logging
 import os
 import re
 
 from pylib import constants
 from pylib.utils import flakiness_dashboard_results_uploader
 
 
 def _LogToFile(results, test_type, suite_name):
   """Log results to local files which can be used for aggregation later."""
   log_file_path = os.path.join(constants.GetOutDirectory(), 'test_logs')
   if not os.path.exists(log_file_path):
     os.mkdir(log_file_path)
   full_file_name = os.path.join(
-      log_file_path, re.sub('\W', '_', test_type).lower() + '.log')
+      log_file_path, re.sub(r'\W', '_', test_type).lower() + '.log')
   if not os.path.exists(full_file_name):
     with open(full_file_name, 'w') as log_file:
       print >> log_file, '\n%s results for %s build %s:' % (
           test_type, os.environ.get('BUILDBOT_BUILDERNAME'),
           os.environ.get('BUILDBOT_BUILDNUMBER'))
     logging.info('Writing results to %s.' % full_file_name)
 
   logging.info('Writing results to %s.' % full_file_name)
   with open(full_file_name, 'a') as log_file:
     shortened_suite_name = suite_name[:25] + (suite_name[25:] and '...')
@@ skipping 71 matching lines @@
     # instrumenation test package using different annotations.
     if annotation and len(annotation) == 1:
       suite_name = annotation[0]
     else:
       suite_name = test_package
     _LogToFile(results, test_type, suite_name)
 
     if flakiness_server:
       _LogToFlakinessDashboard(results, test_type, test_package,
                                flakiness_server)