Linux: Add xcb FD to glib event loop

ui/base/x/ui_base_x.gyp

 # Copyright 2016 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 25 matching lines @@
       ],
       'sources': [
         'ui_base_x_export.h',
         'x11_foreign_window_manager.cc',
         'x11_foreign_window_manager.h',
         'x11_menu_list.cc',
         'x11_menu_list.h',
         'x11_util.cc',
         'x11_util.h',
         'x11_util_internal.h',
+        'x11_window_cache.cc',
+        'x11_window_cache.h',
+        'x11_window_cache_event_source.cc',
+        'x11_window_cache_event_source.h',
       ],
     },
   ],
 }