autotest/factory: improve message feedback on UI

client/site_tests/factory_WriteGBB/factory_WriteGBB.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 glob, os
 
 from autotest_lib.client.bin import factory, test, utils
 from autotest_lib.client.common_lib import error
 from autotest_lib.client.cros import gooftools
 
 
 class factory_WriteGBB(test.test):
     """ Updates system firmware GBB data with probed HWID information. """
     version = 4
 
     def run_once(self):
-        # If found the HwQual ID in shared_data, identify the component files.
-        probed_hwid = factory.get_shared_data('last_probed_hwid')
+        # We trust previous execution result of HWQual ID probing test: by
+        # hardware_Components(do_probe=True).
+        # If the value was incorrect, it will be detected in the finalization
+        # stage (factory_Finalize, gooftool --finalize => --verify_hwid).
+        probed_hwid = factory.get_shared_data(factory.LAST_PROBED_HWID_NAME)
         if not probed_hwid:
             raise error.TestError(
                     'You need to run this test from factory UI, and have ' +
                     'successfully completed the HWQual-ID matching test ')
         gooftools.run('gooftool --write_gbb="%s" --verbose' % probed_hwid)