Guard dbus component and config with assert(use_dbus)

build/config/linux/BUILD.gn

 # Copyright (c) 2013 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/ui.gni")
 
 group("linux") {
   visibility = [ "//:optimize_gn_gen" ]
 }
 
 # This is included by reference in the //build/config/compiler config that
 # is applied to all targets. It is here to separate out the logic that is
 # Linux-only. This is not applied to Android, but is applied to ChromeOS.
 config("compiler") {
   cflags = [ "-pthread" ]
@@ skipping 60 matching lines @@
 }
 
 config("xtst") {
   libs = [ "Xtst" ]
 }
 
 config("libresolv") {
   libs = [ "resolv" ]
 }
 
-pkg_config("glib") {
-  packages = [
-    "glib-2.0",
-    "gmodule-2.0",
-    "gobject-2.0",
-    "gthread-2.0",
-  ]
+if (use_glib) {
+  pkg_config("glib") {
+    packages = [
+      "glib-2.0",
+      "gmodule-2.0",
+      "gobject-2.0",
+      "gthread-2.0",
+    ]
+  }
 }