test: Clean up site_login.py a bit.

client/site_tests/platform_ProcessPrivileges/platform_ProcessPrivileges.py

 # 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.
 
 import time
 from autotest_lib.client.bin import site_login, test, utils
 from autotest_lib.client.common_lib import error
 
 class platform_ProcessPrivileges(test.test):
     version = 1
 
     def setup(self):
         site_login.setup_autox(self)
 
 
     def run_once(self, process='X', user=None, run_as_root=False,
                  do_login=False):
         """Check if the process is running as the specified user / root.
 
         Args:
             process: Process name to check.
             user: User process must run as; ignored if None.
             run_as_root: Is process allowed to run as root?
             do_login: login before getting process information?
         """
         logged_in = site_login.logged_in()
 
         if do_login and not logged_in:
             # Test account information embedded into json file.
-            if not site_login.attempt_login(self, 'autox_script.json'):
-                raise error.TestFail('Could not login')
+            site_login.attempt_login(self, 'autox_script.json')
             # Wait for processes for user-session are started.
             time.sleep(10)
 
         try:
             # Get the process information
             pscmd = 'ps -o f,euser,ruser,suser,fuser,comm -C %s --no-headers'
             ps = utils.system_output(pscmd % process, retain_output=True)
 
             pslines = ps.splitlines()
 
@@ skipping 20 matching lines @@
                     #    raise error.TestFail(
                     #        'Process %s running with super-user flag' %
                     #        process)
                     if 'root' in ps:
                         raise error.TestFail(
                             'Process %s running as root' % process)
         finally:
             # If we started logged out, log back out.
             if do_login and not logged_in:
                 site_login.attempt_logout()