Remove X11 deps from //ui/events:events_base.

ui/events/platform/x11/x11_events_platform.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [{
     # GN version: //ui/events/platform/x11
@@ skipping 27 matching lines @@
         'sources': [
           'x11_event_source_glib.cc',
           'x11_event_source_glib.h',
         ],
       }, {
         # use_glib == 0
         'sources': [
           'x11_event_source_libevent.cc',
           'x11_event_source_libevent.h',
         ],
+        'dependencies': [
+          '../../keycodes/events_keycodes.gyp:keycodes_x',
+        ],
       }],
     ],
   }],
 }