Remove all uses of toolkit_use_gtk in the gyp files.

gpu/command_buffer_service.gypi

 # 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.
 
 {
   'include_dirs': [
     '..',
   ],
   'all_dependent_settings': {
     'include_dirs': [
@@ skipping 113 matching lines @@
     'command_buffer/service/texture_manager.h',
     'command_buffer/service/texture_manager.cc',
     'command_buffer/service/transfer_buffer_manager.cc',
     'command_buffer/service/transfer_buffer_manager.h',
     'command_buffer/service/vertex_array_manager.h',
     'command_buffer/service/vertex_array_manager.cc',
     'command_buffer/service/vertex_attrib_manager.h',
     'command_buffer/service/vertex_attrib_manager.cc',
   ],
   'conditions': [
-    ['toolkit_uses_gtk == 1', {
-      'dependencies': [
-        '../build/linux/system.gyp:gtk',
-      ],
-    }],
     ['ui_compositor_image_transport==1', {
       'include_dirs': [
         '../third_party/khronos',
       ],
     }],
     ['OS in ("win", "android") or (OS == "linux" and use_x11 == 1)', {
       'sources': [
         'command_buffer/service/async_pixel_transfer_manager_egl.cc',
         'command_buffer/service/async_pixel_transfer_manager_egl.h',
       ],
     }],
     ['OS=="android"', {
       'configurations': {
         'Release': {
           'cflags': ['-O2']
         }
       }
     }]
   ],
 }