Make the gyp files more cross-platform across the Unices

ui/ui_unittests.gypi

 # Copyright (c) 2011 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.
 
 {
   'targets': [
     {
       'target_name': 'ui_unittests',
       'type': 'executable',
       'msvs_guid': 'C412B00F-2098-4833-B3DE-A1B8B7A094F0',
@@ skipping 72 matching lines @@
               ],
             },
           },
           'link_settings': {
             'libraries': [
               '-limm32.lib',
               '-loleacc.lib',
             ],
           },
         }],
-        ['OS=="linux" or OS=="freebsd" or OS=="openbsd"', {
+        ['toolkit_uses_gtk == 1', {
           'dependencies': [
             '../app/app.gyp:app_base',
             '../build/linux/system.gyp:gtk',
           ],
           'conditions': [
             ['linux_use_tcmalloc==1', {
                'dependencies': [
                  '../base/allocator/allocator.gyp:allocator',
                ],
             }],
           ],
         }],
       ],
     },
   ],
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: