Make the gyp files more cross-platform across the Unices

content/content_renderer.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': 'content_renderer',
       'msvs_guid': '9AAA8CF2-9B3D-4895-8CB9-D70BBD125EAD',
       'type': '<(library)',
@@ skipping 157 matching lines @@
         }],
         ['enable_gpu==1', {
           'dependencies': [
             '../gpu/gpu.gyp:gles2_c_lib',
           ],
           'sources': [
             'renderer/command_buffer_proxy.cc',
             'renderer/command_buffer_proxy.h',
           ],
         }],
-        ['OS=="linux" or OS=="freebsd" or OS=="openbsd"', {
+        ['toolkit_uses_gtk == 1', {
           'dependencies': [
             '../build/linux/system.gyp:gtk',
           ],
         }],
         ['OS=="mac"', {
           'sources!': [
             'common/process_watcher_posix.cc',
           ],
           'link_settings': {
             'mac_bundle_resources': [
               'renderer/renderer.sb',
             ],
           },
         }],
       ],
     },
   ],
 }