Linux Aura accessibility is enabled only on GNOME desktops

build/linux/system.gyp

 # Copyright (c) 2012 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': {
     'conditions': [
       ['sysroot!=""', {
         'pkg-config': '<(chroot_cmd) ./pkg-config-wrapper "<(sysroot)" "<(target_arch)" "<(system_libdir)"',
       }, {
@@ skipping 674 matching lines @@
     }],
   ],  # conditions
   'targets': [
     {
       'target_name': 'dbus',
       'type': 'none',
       'direct_dependent_settings': {
         'cflags': [
           '<!@(<(pkg-config) --cflags dbus-1)',
         ],
+        'defines': [
+          'USE_DBUS',
+        ],
       },
       'link_settings': {
         'ldflags': [
           '<!@(<(pkg-config) --libs-only-L --libs-only-other dbus-1)',
         ],
         'libraries': [
           '<!@(<(pkg-config) --libs-only-l dbus-1)',
         ],
       },
     },
@@ skipping 516 matching lines @@
                   },
                 }],
               ],
             }],
           ]
         }],
       ],
     },
   ],
 }