Reland of V2 of //tools/binary_size rewrite (diffs).

tools/binary_size/helpers.py

 # Copyright 2017 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.
 
 """Utility methods."""
 
 import atexit
 import distutils.spawn
 import logging
 import os
 import platform
 import resource
 import sys
 
 
 SRC_ROOT = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
 
 
-def AddCommonOptionsAndParseArgs(parser):
+def AddCommonOptionsAndParseArgs(parser, argv):
   parser.add_argument('--no-pypy', action='store_true',
                       help='Do not automatically switch to pypy when available')
   parser.add_argument('-v',
                       '--verbose',
                       default=0,
                       action='count',
                       help='Verbose level (multiple times for more)')
-
-  args = parser.parse_args()
+  args = parser.parse_args(argv[1:])
 
   logging.basicConfig(level=logging.WARNING - args.verbose * 10,
                       format='%(levelname).1s %(relativeCreated)6d %(message)s')
 
   if not args.no_pypy and platform.python_implementation() == 'CPython':
     # Switch to pypy if it's available.
     pypy_path = distutils.spawn.find_executable('pypy')
     if pypy_path:
       logging.debug('Switching to pypy.')
       os.execv(pypy_path, [pypy_path] + sys.argv)
     # NOTE! Running with python: 6s. Running with pypy: 3s
     logging.warning('This script runs more than 2x faster if you install pypy.')
 
   if logging.getLogger().isEnabledFor(logging.DEBUG):
     atexit.register(_LogPeakRamUsage)
   return args
 
 
 def _LogPeakRamUsage():
   peak_ram_usage = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
   peak_ram_usage += resource.getrusage(resource.RUSAGE_CHILDREN).ru_maxrss
   logging.info('Peak RAM usage was %d MB.', peak_ram_usage / 1024)