Enable presubmit pylint in build/android.

build/android/bb_run_sharded_steps.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2012 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.
 
 """DEPRECATED!
 TODO(bulach): remove me once all other repositories reference
 'test_runner.py perf' directly.
 """
 
 import optparse
-import os
 import sys
 
 from pylib import cmd_helper
 
 
 def main(argv):
   parser = optparse.OptionParser()
   parser.add_option('-s', '--steps',
                     help='A JSON file containing all the steps to be '
                          'sharded.')
   parser.add_option('--flaky_steps',
                     help='A JSON file containing steps that are flaky and '
                          'will have its exit code ignored.')
   parser.add_option('-p', '--print_results',
                     help='Only prints the results for the previously '
                          'executed step, do not run it again.')
-  options, urls = parser.parse_args(argv)
+  options, _ = parser.parse_args(argv)
   if options.print_results:
     return cmd_helper.RunCmd(['build/android/test_runner.py', 'perf',
                               '--print-step', options.print_results])
   flaky_options = []
   if options.flaky_steps:
     flaky_options = ['--flaky-steps', options.flaky_steps]
   return cmd_helper.RunCmd(['build/android/test_runner.py', 'perf', '-v',
                             '--steps', options.steps] + flaky_options)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))