Add the first enterprise e2e tests utilizing CELab.

The changes:
- Implementation of the test runner test.py;
- A simple test for policy ForceGoogleSafeSearch;

To run the test, use:

```
python test.py --test tests.ForceGoogleSafeSearchTest \
--test_arg=--chrome_installer=<path_to_mini_installer_exe> \
--test_arg=--chromedriver=<path_to_chromedriver_exe> \
--cel_ctl=<path_to_cel_ctl_exe> \
--host=<path_to_host_file>
```

- the test framework design doc: http://go/chrome-enterprise-test-framework
- doc on writing & running enterprise tests: https://g3doc.corp.google.com/javatests/com/google/chrome/cros/test/celab/g3doc/write_enterprise_test.md?cl=250383764

References: 
Change-Id: I62b10712934507c6619adf36f0b1441c5194a931
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1635870
Commit-Queue: Fei Ling <feiling@chromium.org>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665591}

chrome/browser/policy/e2e_test/.style.yapf

+[style]
+based_on_style = chromium
\ No newline at end of file

chrome/browser/policy/e2e_test/test.py

+# Copyright (c) 2019 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.
+"""The test runner that runs enterprise end-to-end tests."""
+
+import logging
+import sys
+import traceback
+import warnings
+from absl import app
+from absl import flags
+import chrome_ent_test.infra.controller as controller
+
+FLAGS = flags.FLAGS
+
+flags.DEFINE_string(
+    'test', None,
+    'The full class name of the EnterpriseTestCase class (w/ package)')
+flags.mark_flag_as_required('test')
+
+flags.DEFINE_string('test_filter', None,
+                    'The name of the test to run in the test class')
+
+flags.DEFINE_string('host', None,
+                    'The full path to the *.host.textpb file to use')
+flags.mark_flag_as_required('host')
+
+flags.DEFINE_string('cel_ctl', None,
+                    'Which binary to use to deploy the environment')
+flags.mark_flag_as_required('cel_ctl')
+
+flags.DEFINE_bool(
+    'deploy', True, 'Depoly the test environment. '
+    'Set to false to skip the deployment phase and go straight to tests')
+flags.DEFINE_bool(
+    'skip_before_all', False, 'True to skip @before_all methods. '
+    'Like --nodeploy, this is used to skip set up steps. '
+    'Useful when developing new tests.')
+flags.DEFINE_bool('cleanup', False,
+                  'Clean up the host environment after the test')
+flags.DEFINE_string('error_logs_dir', None,
+                    'Where to collect extra logs on test failures')
+flags.DEFINE_multi_string('test_arg', None, 'Flags passed to tests')
+
+
+def ConfigureLogging():
+  # Filter out logs from low level loggers
+  errorOnlyLoggers = [
+      'googleapiclient.discovery_cache', 'google.auth', 'google_auth_httplib2'
+  ]
+  for logger in errorOnlyLoggers:
+    logging.getLogger(logger).setLevel(logging.ERROR)
+  message = 'We recommend that most server applications use service accounts.'
+  warnings.filterwarnings('ignore', '.*%s' % message)
+
+  logging.error("%s: Logging level error is visible." % __file__)
+  logging.warning("%s: Logging level warning is visible." % __file__)
+  logging.info("%s: Logging level info is visible." % __file__)
+  logging.debug("%s: Logging level debug is visible." % __file__)
+
+
+def main(argv):
+  ConfigureLogging()
+
+  c = controller.SingleTestController(
+      FLAGS.test,
+      FLAGS.host,
+      FLAGS.cel_ctl,
+      test_filter=FLAGS.test_filter,
+      skip_before_all=FLAGS.skip_before_all)
+
+  # Parse test specific flags. Note that we need to use a dummy element
+  # as the first element of the list since absl.flags ignores the first element
+  # during parsing.
+  if FLAGS.test_arg is not None:
+    FLAGS([''] + FLAGS.test_arg)
+
+  success = False
+  should_write_logs = (FLAGS.error_logs_dir != None)
+  try:
+    if FLAGS.deploy:
+      c.DeployNewEnvironment()
+
+    success = c.ExecuteTestCase()
+  except KeyboardInterrupt:
+    logging.error('Test aborted.')
+  except:
+    print(traceback.format_exc())
+    logging.error('Test failed.')
+  finally:
+    if not success and should_write_logs:
+      print('Writing Compute logs to "%s"...' % FLAGS.error_logs_dir)
+      c.TryWriteComputeLogsTo(FLAGS.error_logs_dir)
+
+    if FLAGS.cleanup:
+      print('Cleaning up host environment...')
+      c.TryCleanHostEnvironment()
+
+  sys.exit(0 if success else 1)
+
+
+if __name__ == '__main__':
+  app.run(main)

chrome/browser/policy/e2e_test/tests/__init__.py

+# Copyright (c) 2019 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.
+
+from force_google_safe_search.force_google_safe_search import *

chrome/browser/policy/e2e_test/tests/force_google_safe_search/force_google_safe_search.py

+# Copyright (c) 2019 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 os
+import logging
+from chrome_ent_test.infra.core import environment, before_all, test
+from chrome_ent_test.ent_tests import ChromeEnterpriseTestCase
+from absl import flags
+
+FLAGS = flags.FLAGS
+
+
+@environment(file="../policy_test.asset.textpb")
+class ForceGoogleSafeSearchTest(ChromeEnterpriseTestCase):
+
+  @before_all
+  def setup(self):
+    self.InstallChrome('client2012')
+    self.InstallWebDriver('client2012')
+
+  @test
+  def test_ForceGoogleSafeSearchEnabled(self):
+    # enable policy ForceGoogleSafeSearch
+    self.SetPolicy('win2012-dc', 'ForceGoogleSafeSearch', 1, 'DWORD')
+    self.RunCommand('client2012', 'gpupdate /force')
+    logging.info('ForceGoogleSafeSearch ENABLED')
+    d = os.path.dirname(os.path.abspath(__file__))
+    output = self.RunWebDriverTest(
+        'client2012',
+        os.path.join(d, 'force_google_safe_search_webdriver_test.py'))
+    logging.info('url used: %s', output)
+
+    # assert that safe search is enabled
+    self.assertIn('safe=active', output)
+    self.assertIn('ssui=on', output)
+
+  @test
+  def test_ForceGoogleSafeSearchDisabled(self):
+    # disable policy ForceGoogleSafeSearch
+    self.SetPolicy('win2012-dc', 'ForceGoogleSafeSearch', 0, 'DWORD')
+    self.RunCommand('client2012', 'gpupdate /force')
+    d = os.path.dirname(os.path.abspath(__file__))
+    logging.info('ForceGoogleSafeSearch DISABLED')
+    output = self.RunWebDriverTest(
+        'client2012',
+        os.path.join(d, 'force_google_safe_search_webdriver_test.py'))
+    logging.info('url used: %s', output)
+
+    # assert that safe search is NOT enabled
+    self.assertNotIn('safe=active', output)
+    self.assertNotIn('ssui=on', output)

chrome/browser/policy/e2e_test/tests/force_google_safe_search/force_google_safe_search_webdriver_test.py

+# Copyright (c) 2019 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 os
+
+from selenium import webdriver
+from selenium.webdriver.common.by import By
+from selenium.webdriver.support import expected_conditions as EC
+from selenium.webdriver.support.ui import WebDriverWait
+
+os.environ["CHROME_LOG_FILE"] = r"c:\temp\chrome_log.txt"
+
+driver = webdriver.Chrome(
+    "C:/ProgramData/chocolatey/lib/chromedriver/tools/chromedriver.exe",
+    service_args=["--verbose", r"--log-path=c:\temp\chromedriver.log"])
+driver.get('http://www.google.com/xhtml')
+
+# wait for page to be loaded
+wait = WebDriverWait(driver, 10)
+wait.until(EC.visibility_of_element_located((By.NAME, 'q')))
+
+search_box = driver.find_element_by_name('q')
+search_box.send_keys('searchTerm')
+search_box.submit()
+
+# wait for the search result page to be loaded
+wait.until(EC.visibility_of_element_located((By.ID, 'search')))
+
+print driver.current_url
+driver.quit()

chrome/browser/policy/e2e_test/tests/policy_test.asset.textpb

+# The test configuration used by most policy tests.
+# It consists of one domain controller and one client.
+network {
+  name: 'primary'
+}
+
+# An ActiveDirectory domain.
+ad_domain {
+  name: 'test1.com'
+  netbios_name: 'example'
+
+  domain_controller {
+    windows_machine: 'win2012-dc'
+  }
+}
+
+# the domain controller.
+windows_machine {
+  name: 'win2012-dc'
+  machine_type: 'win2012r2'
+  network_interface { network: 'primary' }
+}
+
+windows_machine {
+  name: 'client2012'
+  machine_type: 'win2012r2'
+  network_interface { network: 'primary' }
+  container { ad_domain: 'test1.com' }
+}
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