Return Windows error code when create-process fails.

chrome/chrome_installer.gypi

 # 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.
 
 {
   'variables': {
     'lastchange_path': '../build/util/LASTCHANGE',
     'libpeer_target_type%': 'static_library',
     'branding_dir': 'app/theme/<(branding_path_component)',
     'branding_dir_100': 'app/theme/default_100_percent/<(branding_path_component)',
@@ skipping 320 matching lines @@
             '<(SHARED_INTERMEDIATE_DIR)/chrome/installer/util/installer_util_strings.rc',
             'installer/mini_installer/chrome.release',  # Move to lib
             'installer/mini_installer/appid.h',
             'installer/mini_installer/chrome_appid.cc',
             'installer/mini_installer/configuration.cc',
             'installer/mini_installer/configuration.h',
             'installer/mini_installer/configuration_test.cc',
             'installer/mini_installer/decompress.cc',
             'installer/mini_installer/decompress.h',
             'installer/mini_installer/decompress_test.cc',
+            'installer/mini_installer/mini_installer_constants.cc',
+            'installer/mini_installer/mini_installer_constants.h',
             'installer/mini_installer/mini_string.cc',
             'installer/mini_installer/mini_string.h',
             'installer/mini_installer/mini_string_test.cc',
+            'installer/mini_installer/regkey.cc',
+            'installer/mini_installer/regkey.h',
             'installer/setup/app_launcher_installer.cc',  # Move to lib
             'installer/setup/app_launcher_installer.h',  # Move to lib
             'installer/setup/archive_patch_helper.cc',  # Move to lib
             'installer/setup/archive_patch_helper.h',   # Move to lib
             'installer/setup/archive_patch_helper_unittest.cc',
             'installer/setup/install.cc',               # Move to lib
             'installer/setup/install.h',                # Move to lib
             'installer/setup/install_unittest.cc',
             'installer/setup/install_worker.cc',        # Move to lib
             'installer/setup/install_worker.h',         # Move to lib
@@ skipping 744 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'setup_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }