Always use ENABLE_PLUGINS to indicate plugins support.

chrome/chrome_browser_ui.gypi

 # Copyright 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': {
     # There are two sections of sources:
     # * "Platform"-based sources (OS, toolkit, etc.)
     # * Feature/directory-based sources (e.g., history, printing)
 
@@ skipping 1872 matching lines @@
       'browser/ui/webui/options/startup_pages_handler.cc',
       'browser/ui/webui/options/startup_pages_handler.h',
       'browser/ui/webui/options/supervised_user_create_confirm_handler.cc',
       'browser/ui/webui/options/supervised_user_create_confirm_handler.h',
       'browser/ui/webui/options/supervised_user_import_handler.cc',
       'browser/ui/webui/options/supervised_user_import_handler.h',
       'browser/ui/webui/options/supervised_user_learn_more_handler.cc',
       'browser/ui/webui/options/supervised_user_learn_more_handler.h',
       'browser/ui/webui/options/sync_setup_handler.cc',
       'browser/ui/webui/options/sync_setup_handler.h',
-      'browser/ui/webui/plugins_ui.cc',
-      'browser/ui/webui/plugins_ui.h',
       'browser/ui/webui/profile_info_watcher.cc',
       'browser/ui/webui/profile_info_watcher.h',
       'browser/ui/webui/quota_internals/quota_internals_handler.cc',
       'browser/ui/webui/quota_internals/quota_internals_handler.h',
       'browser/ui/webui/quota_internals/quota_internals_proxy.cc',
       'browser/ui/webui/quota_internals/quota_internals_proxy.h',
       'browser/ui/webui/quota_internals/quota_internals_types.cc',
       'browser/ui/webui/quota_internals/quota_internals_types.h',
       'browser/ui/webui/quota_internals/quota_internals_ui.cc',
       'browser/ui/webui/quota_internals/quota_internals_ui.h',
@@ skipping 743 matching lines @@
       'browser/ui/omnibox/chrome_omnibox_edit_controller.cc',
       'browser/ui/omnibox/chrome_omnibox_edit_controller.h',
       'browser/ui/omnibox/chrome_omnibox_navigation_observer.cc',
       'browser/ui/omnibox/chrome_omnibox_navigation_observer.h',
     ],
     'chrome_browser_ui_plugin_sources': [
       'browser/ui/hung_plugin_tab_helper.cc',
       'browser/ui/hung_plugin_tab_helper.h',
       'browser/ui/webui/flash_ui.cc',
       'browser/ui/webui/flash_ui.h',
+      'browser/ui/webui/plugins_ui.cc',
+      'browser/ui/webui/plugins_ui.h',
     ],
     'chrome_browser_ui_policy_sources': [
       'browser/ui/webui/policy_ui.cc',
       'browser/ui/webui/policy_ui.h',
     ],
     'chrome_browser_ui_print_preview_sources': [
       'browser/ui/webui/print_preview/extension_printer_handler.cc',
       'browser/ui/webui/print_preview/extension_printer_handler.h',
       'browser/ui/webui/print_preview/print_preview_distiller.cc',
       'browser/ui/webui/print_preview/print_preview_distiller.h',
@@ skipping 521 matching lines @@
           ],
           'sources': [
             '<@(chrome_browser_ui_non_mobile_sources)',
             '<@(chrome_browser_ui_omnibox_non_mobile_sources)',
           ],
         }],
       ],
     },
   ],
 }