make use of existing gn args in ui build config

ui/accessibility/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/linux/pkg_config.gni")
+import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/json_schema_api.gni")
 import("//testing/test.gni")
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
 if (use_x11) {
   pkg_config("atk") {
     packages = [ "atk" ]
@@ skipping 81 matching lines @@
     sources += [
       "platform/atk_util_auralinux.cc",
       "platform/atk_util_auralinux.h",
       "platform/ax_platform_node_auralinux.cc",
       "platform/ax_platform_node_auralinux.h",
     ]
 
     configs += [
       ":atk",
       ":atk_warnings",
-      "//build/config/linux/gconf",
-      "//build/config/linux:glib",
     ]
+
+    if (use_gconf) {
+      configs += [ "//build/config/linux/gconf" ]
+    }
+
+    if (use_glib) {
+      configs += [ "//build/config/linux:glib" ]
+    }
   }
 }
 
 if (is_android) {
   android_library("ui_accessibility_java") {
     deps = []
     srcjar_deps = [ ":ax_enumerations_srcjar" ]
   }
 
   java_cpp_enum("ax_enumerations_srcjar") {
@@ skipping 46 matching lines @@
 json_schema_api("ax_gen") {
   sources = [
     "ax_enums.idl",
   ]
   deps = [
     "//base/third_party/dynamic_annotations",
   ]
   root_namespace = "ui"
   schemas = true
 }