Add GN build file for 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/sysroot.gni")
 
 config("sdk") {
   if (sysroot != "") {
     cflags = [ "--sysroot=" + sysroot ]
@@ skipping 30 matching lines @@
 }
 
 pkg_config("pangocairo") {
   packages = [ "pangocairo" ]
 }
 
 pkg_config("udev") {
   packages = [ "libudev" ]
 }
 
+pkg_config("dbus") {
+  packages = [ "dbus-1" ]
+}
+
 config("x11") {
   # Don't bother running pkg-config for these X related libraries since it just
   # returns the same libs, and forking pkg-config is slow.
   libs = [
     "X11",
     "Xcomposite",
     "Xcursor",
     "Xdamage",
     "Xext",
     "Xfixes",
@@ skipping 111 matching lines @@
 
   functions = [
     "pci_alloc",
     "pci_init",
     "pci_cleanup",
     "pci_scan_bus",
     "pci_fill_info",
     "pci_lookup_name",
   ]
 }