Make startup of of WPR components resilient to not starting up previous steps.

tools/cygprofile/profile_android_startup.py

 # Copyright (c) 2015 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.
 
 """Utility library for running a startup profile on an Android device.
 
 Sets up a device for cygprofile, disables sandboxing permissions, and sets up
 support for web page replay, device forwarding, and fake certificate authority
 to make runs repeatable.
 """
@@ skipping 117 matching lines @@
       self._is_test_ca_installed = False
 
     shutil.rmtree(os.path.dirname(self._wpr_ca_cert_path), ignore_errors=True)
     self._wpr_ca_cert_path = None
     self._device_cert_util = None
 
   def _BringUpWpr(self):
     """Start the WPR server on the host and the forwarder on the device."""
     print 'Starting WPR on host...'
     _DownloadFromCloudStorage(self._WPR_BUCKET, self._wpr_archive_hash)
+    args = ['--user_closest_match']
+    if self._is_test_ca_installed:
+      args.extend(['--should_generate_certs',
+                   '--https_root_ca_cert_path=' + self._wpr_ca_cert_path])
     self._wpr_server = webpagereplay.ReplayServer(self._wpr_archive,
-        '127.0.0.1', 0, 0, None,
-        ['--should_generate_certs',
-         '--https_root_ca_cert_path=' + self._wpr_ca_cert_path,
-         '--use_closest_match'])
+        '127.0.0.1', 0, 0, None, args)
     ports = self._wpr_server.StartServer()[:-1]
     self._host_http_port = ports[0]
     self._host_https_port = ports[1]
 
   def _StopWpr(self):
     """ Stop the WPR and forwarder. """
     print 'Stopping WPR on host...'
     if self._wpr_server:
       self._wpr_server.StopServer()
+      self._wpr_server = None
 
   def _StartForwarder(self):
     """Sets up forwarding of device ports to the host, and configures chrome
     to use those ports.
     """
+    if not self._host_http_port or not self._host_https_port:

[pasko, 2015/04/15 09:59:02]

I think it's easier to reason about error cases if we had only one indication of
error case, like _wpr_server==None.

Is it possible that _wpr_server.StartServer() would throw? if so, maybe  cleanup
and set _wpr_server to None?

[azarchs, 2015/04/15 10:54:11]

Done.

+      logging.warning('No host WPR server to forward to.')
+      return
     print 'Starting device forwarder...'
     forwarder.Forwarder.Map([(0, self._host_http_port),
                              (0, self._host_https_port)],
                             self._device)
     device_http = forwarder.Forwarder.DevicePortForHostPort(
         self._host_http_port)
     device_https = forwarder.Forwarder.DevicePortForHostPort(
         self._host_https_port)
     self._flag_changer = flag_changer.FlagChanger(
         self._device, self._cmdline_file)
@@ skipping 176 matching lines @@
     print 'Pulling cyglog data...'
     self._SetUpHostFolders()
     self._device.old_interface.Adb().Pull(
         self._DEVICE_CYGLOG_DIR, self._host_cyglog_dir)
     files = os.listdir(self._host_cyglog_dir)
 
     if len(files) == 0:
       raise NoCyglogDataError('No cyglog data was collected')
 
     return [os.path.join(self._host_cyglog_dir, x) for x in files]