Enable runtime switching between ChromeVox and ChromeVox next via command line.

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.
 {
   'variables': {
     'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/chrome',
     'about_credits_file': '<(SHARED_INTERMEDIATE_DIR)/about_credits.html',
     'additional_modules_list_file': '<(SHARED_INTERMEDIATE_DIR)/chrome/browser/internal/additional_modules_list.txt',
     'omnibox_mojom_file': '<(SHARED_INTERMEDIATE_DIR)/chrome/browser/ui/webui/omnibox/omnibox.mojom.js',
   },
@@ skipping 93 matching lines @@
             {
               # GN version: //chrome/browser/resources:extension_resource_demo
               'destination': '<(PRODUCT_DIR)/resources/extension/demo',
               'files': [
                 'browser/resources/extension_resource/demo/library.js',
               ],
             },
           ],
         }],
         ['chromeos==1 and disable_nacl==0 and disable_nacl_untrusted==0', {
-          'conditions': [
-            # TODO(dtseng): Remove use_chromevox_next once ChromeVox Next is ready for testing.
-            ['use_chromevox_next==1', {
-              'dependencies': [
-                'browser/resources/chromeos/chromevox2/chromevox.gyp:chromevox2',
-              ],
-            }, { # else use_chromevox_next == 0
-              'dependencies': [
-                'browser/resources/chromeos/chromevox/chromevox.gyp:chromevox',
-              ],
-            }],
+          'dependencies': [
+            'browser/resources/chromeos/chromevox/chromevox.gyp:chromevox',
           ],
         }],
         ['enable_extensions==1', {
           'actions': [
             {
               # GN version: //chrome/browser/resources:quota_internals_resources
               'action_name': 'generate_quota_internals_resources',
               'variables': {
                 'grit_grd_file': 'browser/resources/quota_internals_resources.grd',
               },
@@ skipping 441 matching lines @@
                      '<(generator_path)',
                      'credits',
                      '<(about_credits_file)',
           ],
           'message': 'Generating about:credits',
         },
       ],
     },
   ], # targets
 }