Implement the Platform::sharedOffscreenGraphicsContext3D method.

webkit/support/webkit_support.gyp

 # 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.
 
 {
   'includes': [
     '../user_agent/webkit_user_agent.gypi',
   ],
   'conditions': [
     # TODO(stuartmorgan): All dependencies from code built on iOS to
     # webkit/ should be removed, at which point this condition can be
     # removed.
     ['OS != "ios"', {
       'includes': [
         '../../build/win_precompile.gypi',
         '../appcache/webkit_appcache.gypi',
         '../base/webkit_base.gypi',
         '../database/webkit_database.gypi',
         '../glue/webkit_glue.gypi',
-        '../gpu/webkit_gpu.gypi',
         '../media/webkit_media.gypi',
         '../quota/webkit_quota.gypi',
         '../storage/webkit_storage.gypi',
         'webkit_support.gypi',
       ],
     }],
   ],
 }