remove duplicate atk GN config

ui/accessibility/BUILD.gn

Index: ui/accessibility/BUILD.gn
diff --git a/ui/accessibility/BUILD.gn b/ui/accessibility/BUILD.gn
index 2c9b49dea289a9c21ae1e84497fc02e6d6910f95..4c03ce91d34e55a5f9e7465509fafdb339a30adc 100644
--- a/ui/accessibility/BUILD.gn
+++ b/ui/accessibility/BUILD.gn
@@ -11,34 +11,6 @@ if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
-if (use_x11) {
-  pkg_config("atk") {
-    packages = [ "atk" ]
-    atk_lib_dir = exec_script(pkg_config_script,
-                              pkg_config_args + [
-                                    "--libdir",
-                                    "atk",
-                                  ],
-                              "string")
-    defines = [ "ATK_LIB_DIR=\"$atk_lib_dir\"" ]
-  }
-
-  # gn orders flags on a target before flags from configs. The default config
-  # adds -Wall, and these flags have to be after -Wall -- so they need to come
-  # from a config and can't be on the target directly.
-  config("atk_warnings") {
-    cflags = [
-      # glib uses the pre-c++11 typedef-as-static_assert hack.
-      "-Wno-unused-local-typedef",
-
-      # G_DEFINE_TYPE automatically generates a *get_instance_private
-      # inline function after glib 2.37. That's unused. Prevent to
-      # complain about it.
-      "-Wno-unused-function",
-    ]
-  }
-}
-
 component("accessibility") {
   sources = [
     "ax_node.cc",
@@ -104,10 +76,7 @@ component("accessibility") {
       "platform/ax_platform_node_auralinux.h",
     ]
 
-    configs += [
-      ":atk",
-      ":atk_warnings",
-    ]
+    configs += [ "//build/config/linux/atk" ]
 
     if (use_gconf) {
       configs += [ "//build/config/linux/gconf" ]