Remove inside_chromium_build gyp variable

content/content_worker.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.
 
 {
   'dependencies': [
     '../base/base.gyp:base',
     '../skia/skia.gyp:skia',
-    '<(webkit_src_dir)/Source/WebKit/chromium/WebKit.gyp:webkit',
+    '../third_party/WebKit/Source/WebKit/chromium/WebKit.gyp:webkit',
   ],
   'sources': [
     'worker/shared_worker_devtools_agent.cc',
     'worker/shared_worker_devtools_agent.h',
     'worker/websharedworker_stub.cc',
     'worker/websharedworker_stub.h',
     'worker/websharedworkerclient_proxy.cc',
     'worker/websharedworkerclient_proxy.h',
     'worker/worker_main.cc',
     'worker/worker_thread.cc',
     'worker/worker_thread.h',
     'worker/worker_webapplicationcachehost_impl.cc',
     'worker/worker_webapplicationcachehost_impl.h',
     'worker/worker_webkitplatformsupport_impl.cc',
     'worker/worker_webkitplatformsupport_impl.h',
   ],
   'include_dirs': [
     '..',
   ],
 }