[Chromedriver] Chromedriver should handle unexpected alert automatically.

chrome/test/chromedriver/client/chromedriver.py

 # Copyright 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.
 
 import sys
 import platform
 
 import command_executor
 from command_executor import Command
 from webelement import WebElement
@@ skipping 93 matching lines @@
   """Starts and controls a single Chrome instance on this machine."""
 
   def __init__(self, server_url, chrome_binary=None, android_package=None,
                android_activity=None, android_process=None,
                android_use_running_app=None, chrome_switches=None,
                chrome_extensions=None, chrome_log_path=None,
                debugger_address=None, logging_prefs=None,
                mobile_emulation=None, experimental_options=None,
                download_dir=None, network_connection=None,
                send_w3c_capability=None, send_w3c_request=None,
-               page_load_strategy=None):
+               page_load_strategy=None, unexpected_alert_behaviour=None):
     self._executor = command_executor.CommandExecutor(server_url)
 
     options = {}
 
     if experimental_options:
       assert isinstance(experimental_options, dict)
       options = experimental_options.copy()
 
     if android_package:
       options['androidPackage'] = android_package
@@ skipping 58 matching lines @@
       'desiredCapabilities': {
         'chromeOptions': options,
         'loggingPrefs': logging_prefs
       }
     }
 
     if page_load_strategy:
       assert type(page_load_strategy) is str
       params['desiredCapabilities']['pageLoadStrategy'] = page_load_strategy
 
+    if unexpected_alert_behaviour:
+      assert type(unexpected_alert_behaviour) is str
+      params['desiredCapabilities']['unexpectedAlertBehaviour'] = (
+          unexpected_alert_behaviour)
+
     if network_connection:
       params['desiredCapabilities']['networkConnectionEnabled'] = (
           network_connection)
 
     if send_w3c_request:
       params = {'capabilities': params}
 
     response = self._ExecuteCommand(Command.NEW_SESSION, params)
     if isinstance(response['status'], basestring):
       self.w3c_compliant = True
@@ skipping 291 matching lines @@
     self.ExecuteCommand(Command.DELETE_SCREEN_ORIENTATION)
 
   def SendKeys(self, *values):
     typing = []
     for value in values:
       if isinstance(value, int):
         value = str(value)
       for i in range(len(value)):
         typing.append(value[i])
     self.ExecuteCommand(Command.SEND_KEYS_TO_ACTIVE_ELEMENT, {'value': typing})