Set ui::KeyEvent::key_ (DOM Level 3 key) under X11.

ui/events/events.gyp

 # Copyright 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 63 matching lines @@
       'export_dependent_settings': [
         '../../ui/gfx/gfx.gyp:gfx',
       ],
       'conditions': [
         ['use_x11==1', {
           'dependencies': [
             '../../build/linux/system.gyp:x11',
             '../gfx/x/gfx_x11.gyp:gfx_x11',
           ],
         }],
+        ['use_x11==1 or use_xkbcommon==1', {
+          'sources': [
+            'keycodes/keyboard_code_conversion_xkb.cc',
+            'keycodes/keyboard_code_conversion_xkb.h',
+            'keycodes/xkb_keysym.h',
+          ],
+        }],
       ],
     },
     {
       # GN version: //ui/events
       'target_name': 'events',
       'type': '<(component)',
       'dependencies': [
         '<(DEPTH)/base/base.gyp:base',
         '<(DEPTH)/base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
         '<(DEPTH)/skia/skia.gyp:skia',
@@ skipping 381 matching lines @@
               'dependencies': [
                 '../../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }