[chromeos] Fix Logout automation when no browser windows are present.

chrome/test/pyautolib/pyauto.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """PyAuto: Python Interface to Chromium's Automation Proxy.
 
 PyAuto uses swig to expose Automation Proxy interfaces to Python.
 For complete documentation on the functionality available,
 run pydoc on this file.
@@ skipping 4099 matching lines @@
     observer_id = self._AddLoginEventObserver()
     ret = self.ExecuteJavascriptInOOBEWebUI("""
         chrome.send("completeLogin", ["%s", "%s"] );
         window.domAutomationController.send("success");""" %
         (username, password));
     return self.GetNextEvent(observer_id).get('error_string')
 
   def Logout(self):
     """Log out from ChromeOS and wait for session_manager to come up.
 
-    May return before logout is complete and
-    gives no indication of success or failure.
-    Should be logged in to work.
+    This is equivalent to pressing the 'Sign out' button from the
+    aura shell tray when logged in.
+
+    Should be logged in to work. Re-initializes the automation channel
+    after logout.
     """
     assert self.GetLoginInfo()['is_logged_in'], \
         'Trying to log out when already logged out.'
-    assert self.WaitForSessionManagerRestart(
-        lambda: self.ApplyAccelerator(IDC_EXIT)), \
+    def _SignOut():
+      cmd_dict = { 'command': 'SignOut' }
+      self._GetResultFromJSONRequest(cmd_dict, windex=None)
+    assert self.WaitForSessionManagerRestart(_SignOut), \
         'Session manager did not restart after logout.'
     self.__SetUp()
 
   def LockScreen(self):
     """Locks the screen on chromeos.
 
     Waits until screen is locked.
     Should be logged in and screen should not be locked to work.
 
     Raises:
@@ skipping 1604 matching lines @@
     successful = result.wasSuccessful()
     if not successful:
       pyauto_tests_file = os.path.join(self.TestsDir(), self._tests_filename)
       print >>sys.stderr, 'Tests can be disabled by editing %s. ' \
                           'Ref: %s' % (pyauto_tests_file, _PYAUTO_DOC_URL)
     sys.exit(not successful)
 
 
 if __name__ == '__main__':
   Main()