Get rid of the use_glib gn variable.

ui/events/platform/x11/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.
 
 component("x11") {
   output_name = "x11_events_platform"
 
   sources = [
     "x11_event_source.cc",
     "x11_event_source.h",
-    "x11_event_source_glib.cc",

[viettrungluu, 2015/11/12 02:35:41]

Note: This file doesn't actually currently exist.

     "x11_event_source_libevent.cc",
     "x11_hotplug_event_handler.cc",
     "x11_hotplug_event_handler.h",
   ]
 
   defines = [ "EVENTS_IMPLEMENTATION" ]
 
   configs += [ "//build/config/linux:x11" ]
 
   public_deps = [
     "//ui/events",
     "//ui/events:events_base",
     "//ui/events/devices",
     "//ui/events/platform",
     "//ui/gfx/x",
   ]
 
   deps = [
     "//base",
   ]
-
-  if (use_glib) {
-    sources -= [ "x11_event_source_libevent.cc" ]
-
-    configs += [ "//build/config/linux:glib" ]
-  } else {
-    sources -= [ "x11_event_source_glib.cc" ]
-  }
 }