Add an alternative way to specify extra chrome flags via env for testing

chrome/test/pyautolib/pyauto.py

 #!/usr/bin/python
 
 # Copyright (c) 2011 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.
 
 """PyAuto: Python Interface to Chromium's Automation Proxy.
 
 PyAuto uses swig to expose Automation Proxy interfaces to Python.
 For complete documentation on the functionality available,
@@ skipping 3493 matching lines @@
 
   def _Run(self):
     """Run the tests."""
     if self._options.wait_for_debugger:
       raw_input('Attach debugger to process %s and hit <enter> ' % os.getpid())
 
     suite_args = [sys.argv[0]]
     chrome_flags = self._options.chrome_flags
     # Set CHROME_HEADLESS. It enables crash reporter on posix.
     os.putenv('CHROME_HEADLESS', '1')
-    # --dom-automation added in PyUITestBase::PyUITestBase()
-
-    suite_args.append('--extra-chrome-flags=%s' % chrome_flags)
-    # Note: The suite_args passed here are ignored on windows since it
-    # overrides to obtain the command line for the current process directly.
-    # Refer CommandLine::Init().
+    os.putenv('EXTRA_CHROME_FLAGS', chrome_flags)
     pyauto_suite = PyUITestSuite(suite_args)
     test_names = self._ExpandTestNames(self._args)
     test_names *= self._options.repeat
     logging.debug("Loading %d tests from %s", len(test_names), test_names)
     if self._options.list_tests:  # List tests and exit
       for name in test_names:
         print name
       sys.exit(0)
     loaded_tests = unittest.defaultTestLoader.loadTestsFromNames(test_names)
     pyauto_suite.addTests(loaded_tests)
     verbosity = 1
     if self._options.verbose:
       verbosity = 2
     result = PyAutoTextTestRuner(verbosity=verbosity).run(pyauto_suite)
     del loaded_tests  # Need to destroy test cases before the suite
     del pyauto_suite
     sys.exit(not result.wasSuccessful())
 
 
 if __name__ == '__main__':
   Main()