Remove all uses of toolkit_use_gtk in the gyp files.

ui/base/ui_base.gyp

 # Copyright 2014 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 358 matching lines @@
             'resource/resource_bundle_auralinux.cc',
           ],
         }],
         ['use_aura==1 and OS=="win"', {
           'sources/': [
             ['exclude', 'dragdrop/drag_utils_aura.cc'],
           ],
         }],
         ['use_glib == 1', {
           'dependencies': [
-            # font_gtk.cc uses fontconfig.
             '../../build/linux/system.gyp:fontconfig',
             '../../build/linux/system.gyp:glib',
           ],
         }],
         ['desktop_linux == 1 or chromeos == 1', {
           'conditions': [
             ['toolkit_views==0 and use_aura==0', {
               # Note: because of gyp predence rules this has to be defined as
               # 'sources/' rather than 'sources!'.
               'sources/': [
@@ skipping 195 matching lines @@
            'variables': {
              'jni_gen_package': 'ui',
              'jni_generator_ptr_type': 'long',
            },
            'includes': [ '../../build/jni_generator.gypi' ],
          },
        ],
     }],
   ],
 }