Fix perf trybots after recent refactor.

tools/run-bisect-perf-regression.py

 #!/usr/bin/env python
 # 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.
 
 """Run Performance Test Bisect Tool
 
 This script is used by a trybot to run the src/tools/bisect-perf-regression.py
 script with the parameters specified in run-bisect-perf-regression.cfg. It will
 check out a copy of the depot in a subdirectory 'bisect' of the working
 directory provided, and run the bisect-perf-regression.py script there.
 
 """
 
 import imp
 import optparse
 import os
 import platform
 import subprocess
 import sys
 import traceback
 
 from auto_bisect import bisect_utils
+from auto_bisect import math_utils
 
 bisect = imp.load_source('bisect-perf-regression',
     os.path.join(os.path.abspath(os.path.dirname(sys.argv[0])),
         'bisect-perf-regression.py'))
 
 
 CROS_BOARD_ENV = 'BISECT_CROS_BOARD'
 CROS_IP_ENV = 'BISECT_CROS_IP'
 
 # Default config file names.
@@ skipping 267 matching lines @@
     cloud_file_link = [t for t in cloud_file_link.split(' ')
         if 'storage.googleapis.com/chromium-telemetry/html-results/' in t]
     assert cloud_file_link, "Couldn't parse url from output."
     cloud_file_link = cloud_file_link[0]
   else:
     cloud_file_link = ''
 
   # Calculate the % difference in the means of the 2 runs.
   percent_diff_in_means = (results_with_patch[0]['mean'] /
       max(0.0001, results_without_patch[0]['mean'])) * 100.0 - 100.0
-  std_err = bisect.CalculatePooledStandardError(
+  std_err = math_utils.PooledStandardError(
       [results_with_patch[0]['values'], results_without_patch[0]['values']])
 
   bisect_utils.OutputAnnotationStepClosed()
   bisect_utils.OutputAnnotationStepStart('Results - %.02f +- %0.02f delta' %
       (percent_diff_in_means, std_err))
   print ' %s %s %s' % (''.center(10, ' '), 'Mean'.center(20, ' '),
       'Std. Error'.center(20, ' '))
   print ' %s %s %s' % ('Patch'.center(10, ' '),
       ('%.02f' % results_with_patch[0]['mean']).center(20, ' '),
       ('%.02f' % results_with_patch[0]['std_err']).center(20, ' '))
@@ skipping 228 matching lines @@
           config, current_dir, opts.path_to_goma)
 
   print ('Error: Could not load config file. Double check your changes to '
          'run-bisect-perf-regression.cfg or run-perf-test.cfg for syntax '
          'errors.\n')
   return 1
 
 
 if __name__ == '__main__':
   sys.exit(main())