Fix waiting for ui on reboot.

client/site_tests/suite_Factory/control

 # -*- coding: utf-8 -*-
 #
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 AUTHOR = "Chrome OS Team"
 NAME = "Factory"
 TIME = "LONG"
 TEST_CATEGORY = "Functional"
@@ skipping 51 matching lines @@
 
 # This exec defines TEST_LIST in global scope.
 execfile(TEST_LIST_PATH)
 
 
 # Hack to work around autotest's obsession with GRUB.
 job.bootloader.set_default = lambda x: None
 job.bootloader.boot_once = lambda x: None
 
 
+def start_ui():
+  ui_proc_args = [FACTORY_UI_PATH, TEST_LIST_PATH,
+                  STATUS_FILE_PATH, str(os.getpid())]
+  factory.log('starting ui -- %s' % repr(ui_proc_args))
+  sp = subprocess.Popen(ui_proc_args, stdout=subprocess.PIPE)
+  factory.log('waiting for ui to come up...')
+  factory.log('got message from UI : %s' % repr(sp.stdout.readline().strip()))
+
+
 def step_reboot_seq(tag_prefix, total_iterations, i=0):
     if i < total_iterations:
         job.next_step_prepend([step_reboot_seq, tag_prefix,
                                total_iterations, i + 1])
         factory.log('rebooting (iteration %d of %d)' % (i, total_iterations))
         job.reboot()
     else:
         step_init(intentional_reboot_subtest_tag_prefix=tag_prefix)
 
 
 def step_init(intentional_reboot_subtest_tag_prefix=None):
     job.next_step([step_init])
 
-    ui_proc_args = [FACTORY_UI_PATH, TEST_LIST_PATH,
-                    STATUS_FILE_PATH, str(os.getpid())]
-    factory.log('starting ui -- %s' % repr(ui_proc_args))
-    ui_proc = subprocess.Popen(ui_proc_args)
+    start_ui()
 
     status_map = factory.StatusMap(TEST_LIST, STATUS_FILE_PATH)
     control_state = factory.ControlState(
         job, TEST_LIST, status_map, STATUS_FILE_PATH,
         parallel.fork_nuke_subprocess)
 
     if intentional_reboot_subtest_tag_prefix:
         reboot_subtest = status_map.test_db.get_subtest_by_tag_prefix(
             intentional_reboot_subtest_tag_prefix)
         control_state.run_test(reboot_subtest)
@@ skipping 10 matching lines @@
                     step_reboot_seq(tag_prefix, subtest.iterations)
                 else:
                     control_state.run_test(subtest)
                 if control_state.activated_kbd_shortcut_test:
                     break
         else:
             control_state.run_test(test)
         status_map.read_new_data()
         test = (control_state.activated_kbd_shortcut_test or
                 status_map.next_untested())