Add chrome.loadAsync capability to ChromeDriver, which allows the user not to

chrome/chrome_tests.gypi

 # 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.
 
 {
   'variables' : {
     'pyautolib_sources': [
       'app/chrome_command_ids.h',
       'app/chrome_dll_resource.h',
       'common/automation_constants.h',
@@ skipping 847 matching lines @@
         'test/webdriver/keycode_text_conversion_mac.mm',
         'test/webdriver/keycode_text_conversion_win.cc',
         'test/webdriver/keymap.h',
         'test/webdriver/keymap.cc',
         'test/webdriver/session.h',
         'test/webdriver/session.cc',
         'test/webdriver/session_manager.h',
         'test/webdriver/session_manager.cc',
         'test/webdriver/utility_functions.h',
         'test/webdriver/utility_functions.cc',
+        'test/webdriver/utility_functions_mac.mm',
         'test/webdriver/webdriver_error.h',
         'test/webdriver/webdriver_error.cc',
         'test/webdriver/webdriver_logging.h',
         'test/webdriver/webdriver_logging.cc',
         'test/webdriver/webdriver_key_converter.h',
         'test/webdriver/webdriver_key_converter.cc',
         'test/webdriver/web_element_id.h',
         'test/webdriver/web_element_id.cc',
         'test/webdriver/commands/alert_commands.h',
         'test/webdriver/commands/alert_commands.cc',
@@ skipping 3240 matching lines @@
               # Use outputs of this action as inputs for the main target build.
               # Seems as a misnomer but makes this happy on Linux (scons).
               'process_outputs_as_sources': 1,
             },
           ],  # 'actions'
         },
       ]
     }],  # 'coverage!=0'
   ],  # 'conditions'
 }