make use of existing gn args in ui build config

ui/accessibility/BUILD.gn

Index: ui/accessibility/BUILD.gn
diff --git a/ui/accessibility/BUILD.gn b/ui/accessibility/BUILD.gn
index 036665a61cf0e606a24e4cc4d432cf78948ed8e9..34f63b115f3a5c95f8b39156d5066431406ed22f 100644
--- a/ui/accessibility/BUILD.gn
+++ b/ui/accessibility/BUILD.gn
@@ -3,6 +3,7 @@
 # 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")
@@ -104,9 +105,15 @@ component("accessibility") {
     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" ]
+    }
   }
 }