Add variations combinations testing framework

tools/chrome_proxy/webdriver/common.py

 # Copyright 2016 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 argparse
 import json
 import logging
 import os
 import re
 import socket
@@ skipping 148 matching lines @@
     def GetDictKey(argument):
       return argument.split('=', 1)[0]
     if self._flags.browser_args and len(self._flags.browser_args) > 0:
       # Build a dict of flags mapped to the whole argument.
       original_args = {}
       for arg in self._chrome_args:
           original_args[GetDictKey(arg)] = arg
       # Override flags given in code with any command line arguments.
       for override_arg in shlex.split(self._flags.browser_args):
         arg_key = GetDictKey(override_arg)
-        if arg_key in original_args:
+        if (arg_key in original_args
+            and original_args[arg_key] in self._chrome_args):
           self._chrome_args.remove(original_args[arg_key])
           self._logger.info('Removed Chrome flag. %s', original_args[arg_key])
         self._chrome_args.add(override_arg)
         self._logger.info('Added Chrome flag. %s', override_arg)
     # Always add the flag that allows histograms to be queried in javascript.
     self._chrome_args.add('--enable-stats-collection-bindings')
 
   def _StartDriver(self):
     """Parses the flags to pass to Chromium, then starts the ChromeDriver.
 
@@ skipping 489 matching lines @@
     for test_suite in test_suite_iter:
       for test_case in test_suite:
         for test in test_case:
           # Drop the file name in the form <filename>.<classname>.<methodname>
           test_id = test.id()[test.id().find('.') + 1:]
           if re.match(test_filter_re, test_id):
             tests.addTest(test)
     testRunner = unittest.runner.TextTestRunner(verbosity=2,
       failfast=flags.failfast, buffer=(not flags.disable_buffer))
     testRunner.run(tests)