MD Downloads: add a use_vulcanize option to Chrome

chrome/chrome_resources.gyp

 # 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.
 {
   'includes': [
     'chrome_features.gypi',
   ],
   'variables': {
     # Apply Chrome-specific grit settings to all grit actions in this file.
     'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/chrome',
@@ skipping 185 matching lines @@
         'chrome_internal_resources_gen',
         'chrome_web_ui_mojo_bindings.gyp:web_ui_mojo_bindings',
       ],
       'actions': [
         {
           # GN version: //chrome/browser:resources
           'action_name': 'generate_browser_resources',
           'variables': {
             'grit_grd_file': 'browser/browser_resources.grd',
             'grit_additional_defines': [
+              # TODO(dbeam): 'chrome_grit_defines' should just be appended to
+              # this list of 'grit_additional_defines' via the top of this file,
+              # but they're not for some reason. Maybe because they're in
+              # different scopes?
+              '<@(chrome_grit_defines)',
               '-E', 'additional_modules_list_file=<(additional_modules_list_file)',
               '-E', 'root_gen_dir=<(SHARED_INTERMEDIATE_DIR)',
             ],
           },
           'includes': [ '../build/grit_action.gypi' ],
         },
         {
           # GN version: //chrome/common:resources
           'action_name': 'generate_common_resources',
           'variables': {
@@ skipping 482 matching lines @@
               '<(SHARED_INTERMEDIATE_DIR)/chrome/webui_test_resources.pak',
             ],
             'pak_output': '<(PRODUCT_DIR)/browser_tests.pak',
           },
           'includes': [ '../build/repack_action.gypi' ],
         },
       ],
     },
   ], # targets
 }