autotest: Make WM tests wait for initial browser window.

client/site_tests/desktopui_WindowManagerHotkeys/desktopui_WindowManagerHotkeys.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 os, random, re, shutil, time
-from autotest_lib.client.bin import site_ui_test, site_utils, test, utils
+from autotest_lib.client.bin import site_login, site_ui_test, site_utils, \
+        test, utils
 from autotest_lib.client.common_lib import error
 
 class desktopui_WindowManagerHotkeys(site_ui_test.UITest):
     version = 1
 
     def run_once(self):
+        # Make sure that we don't have the initial browser window popping up in
+        # the middle of the test.
+        site_login.wait_for_initial_chrome_window()
+
         ax = self.get_autox()
 
         # Start a terminal and wait for it to get the focus.
         orig_active_win_xid = ax.get_active_window_property()
         ax.send_hotkey('Ctrl-Alt-t')
         ax.await_condition(
             lambda: ax.get_active_window_property() != orig_active_win_xid,
             desc='Waiting for terminal to become active window')
 
         # Press the Print Screen key and check that a screenshot is written.
         screenshot_dir = '/home/chronos/user/Downloads/Screenshots'
         shutil.rmtree(screenshot_dir, ignore_errors=True)
         ax.send_hotkey('Print')
         site_utils.poll_for_condition(
             lambda: os.access(screenshot_dir, os.F_OK) and \
                     os.listdir(screenshot_dir),
             error.TestFail(
                 'Waiting for screenshot in %s' % screenshot_dir))
         shutil.rmtree(screenshot_dir, ignore_errors=True)