Autotest for ScreenLocker
 * Removed old ScreenSaverUnlock and utility methods
 * Added new ScreenLocker test
 * updated site_ui_tests.py so that it can process dbus signal.
 * Changed poll_for_condition to use TimeoutError (assuming that's the intention)

BUG=chromium-os:2918
TEST=new desktopui_ScreenLocker test should pass

Review URL: http://codereview.chromium.org/3073014
diff --git a/client/bin/site_utils.py b/client/bin/site_utils.py
index 2e3caf3..d03ad8e 100644
--- a/client/bin/site_utils.py
+++ b/client/bin/site_utils.py
@@ -35,6 +35,6 @@
                 desc = 'Timed out waiting for condition: %s' % desc
             else:
                 desc = 'Timed out waiting for unnamed condition'
-            raise error.TestError(desc)
+            raise TimeoutError, desc
 
         time.sleep(sleep_interval)