replace platform conditions with os_posix and os_bsd where applicable

ui/ui.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'includes': [
     'ui_resources.gypi',
@@ skipping 572 matching lines @@
             'gfx/pango_util.cc',
             'gfx/platform_font_pango.cc',
             'gfx/platform_font_pango.h',
           ],
         }],
         ['OS=="linux"', {
           'libraries': [
             '-ldl',
           ],
         }],
-        ['OS=="openbsd" and use_system_libjpeg==1', {
+        ['os_bsd==1 and use_system_libjpeg==1', {
           'include_dirs': [
             '/usr/local/include',
           ],
         }],
       ],
     },
     {
       'target_name': 'gfx_resources',
       'type': 'none',
       'variables': {
@@ skipping 41 matching lines @@
                 'shutil.copyfile(\'<(ui_copy_target)\', \'<(ui_copy_dest)\'); ' \
                 'os.chmod(\'<(ui_copy_dest)\', 0700)'
               ]
             }
           ],
         },
       ],
     }],
   ],
 }