[chrome_remote_control] Add pylint to PRESUMMIT and fix lint

tools/chrome_remote_control/chrome_remote_control/multi_page_benchmark.py

 # 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.
 import csv
 import logging
 import os
 import sys
-import traceback
 
 from chrome_remote_control import browser_finder
 from chrome_remote_control import browser_options
 from chrome_remote_control import page_runner
 from chrome_remote_control import page_set
 from chrome_remote_control import page_test
-from chrome_remote_control import util
 
 class MeasurementFailure(page_test.Failure):
   """Exception that can be thrown from MeasurePage to indicate an undesired but
   designed-for problem."""
   pass
 
 class BenchmarkResults(page_test.PageTestResults):
   def __init__(self):
     super(BenchmarkResults, self).__init__()
     self.page_results = []
@@ skipping 94 matching lines @@
 
   If args is not specified, sys.argv[1:] is used.
   """
   options = browser_options.BrowserOptions()
   parser = options.CreateParser('%prog [options] <page_set>')
   benchmark.AddOptions(parser)
   _, args = parser.parse_args(args)
 
   if len(args) != 1:
     parser.print_usage()
-    import page_sets
+    import page_sets # pylint: disable=F0401
     sys.stderr.write('Available pagesets:\n%s\n\n' % ',\n'.join(
         [os.path.relpath(f) for f in page_sets.GetAllPageSetFilenames()]))
     sys.exit(1)
 
   ps = page_set.PageSet.FromFile(args[0])
 
   benchmark.CustomizeBrowserOptions(options)
   possible_browser = browser_finder.FindBrowser(options)
   if possible_browser == None:
     sys.stderr.write(
       'No browser found.\n' +
       'Use --browser=list to figure out which are available.\n')
     sys.exit(1)
 
   results = CsvBenchmarkResults(csv.writer(sys.stdout))
   with page_runner.PageRunner(ps) as runner:
     runner.Run(options, possible_browser, benchmark, results)
 
   if len(results.page_failures):
     logging.warning('Failed pages: %s', '\n'.join(
         [failure['page'].url for failure in results.page_failures]))
   return max(255, len(results.page_failures))