Build a few more extensions files only when extensions are enabled.

chrome/chrome_browser.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': {
     # All .cc, .h, .m, and .mm files under browser except for:
     # * tests and mocks.
     # * code below browser/chromeos
     # * code below browser/extensions
@@ skipping 1014 matching lines @@
       'browser/profiles/profile_window.cc',
       'browser/profiles/profile_window.h',
       'browser/profiles/profiles_state.cc',
       'browser/profiles/profiles_state.h',
       'browser/profiles/startup_task_runner_service.cc',
       'browser/profiles/startup_task_runner_service.h',
       'browser/profiles/startup_task_runner_service_factory.cc',
       'browser/profiles/startup_task_runner_service_factory.h',
       'browser/profiles/storage_partition_descriptor.h',
       'browser/remove_rows_table_model.h',
-      'browser/renderer_context_menu/context_menu_content_type_app_mode.cc',
-      'browser/renderer_context_menu/context_menu_content_type_app_mode.h',
-      'browser/renderer_context_menu/context_menu_content_type_extension_popup.cc',
-      'browser/renderer_context_menu/context_menu_content_type_extension_popup.h',
       'browser/renderer_context_menu/context_menu_content_type_factory.cc',
       'browser/renderer_context_menu/context_menu_content_type_factory.h',
       'browser/renderer_context_menu/context_menu_content_type_panel.cc',
       'browser/renderer_context_menu/context_menu_content_type_panel.h',
-      'browser/renderer_context_menu/context_menu_content_type_platform_app.cc',
-      'browser/renderer_context_menu/context_menu_content_type_platform_app.h',
       'browser/renderer_context_menu/spellchecker_submenu_observer.h',
       'browser/renderer_context_menu/spellchecker_submenu_observer_mac.cc',
       'browser/renderer_host/chrome_render_message_filter.cc',
       'browser/renderer_host/chrome_render_message_filter.h',
       'browser/renderer_host/chrome_render_widget_host_view_mac_delegate.h',
       'browser/renderer_host/chrome_render_widget_host_view_mac_delegate.mm',
       'browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.h',
       'browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.mm',
       'browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc',
       'browser/renderer_host/chrome_resource_dispatcher_host_delegate.h',
@@ skipping 382 matching lines @@
       'browser/guest_view/web_view/chrome_web_view_guest_delegate.cc',
       'browser/guest_view/web_view/chrome_web_view_guest_delegate.h',
       'browser/guest_view/web_view/chrome_web_view_permission_helper_delegate.cc',
       'browser/guest_view/web_view/chrome_web_view_permission_helper_delegate.h',
       'browser/guest_view/web_view/context_menu_content_type_web_view.cc',
       'browser/guest_view/web_view/context_menu_content_type_web_view.h',
       'browser/infobars/infobar_extension_api.cc',
       'browser/infobars/infobar_extension_api.h',
       'browser/metrics/extensions_metrics_provider.cc',
       'browser/metrics/extensions_metrics_provider.h',
+      'browser/renderer_context_menu/context_menu_content_type_app_mode.cc',
+      'browser/renderer_context_menu/context_menu_content_type_app_mode.h',
+      'browser/renderer_context_menu/context_menu_content_type_extension_popup.cc',
+      'browser/renderer_context_menu/context_menu_content_type_extension_popup.h',
+      'browser/renderer_context_menu/context_menu_content_type_platform_app.cc',
+      'browser/renderer_context_menu/context_menu_content_type_platform_app.h',
       'browser/renderer_host/chrome_extension_message_filter.cc',
       'browser/renderer_host/chrome_extension_message_filter.h',
       'browser/safe_json_parser.cc',
       'browser/safe_json_parser.h',
       'browser/search/hotword_client.h',
       'browser/search/hotword_service.cc',
       'browser/search/hotword_service.h',
       'browser/search/hotword_service_factory.cc',
       'browser/search/hotword_service_factory.h',
       'browser/signin/easy_unlock_auth_attempt.cc',
@@ skipping 2156 matching lines @@
           'variables': {
             'proto_in_dir': 'browser/sync_file_system/drive_backend',
             'proto_out_dir': 'chrome/browser/sync_file_system/drive_backend',
           },
           'includes': [ '../build/protoc.gypi' ]
         },
       ],
     },],
   ],
 }