Remove inside_chromium_build gyp variable

webkit/user_agent/webkit_user_agent.gypi

 # Copyright 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.
 
 {
-  'variables': {
-    'webkit_src_dir': '../../third_party/WebKit/Source',
-  },
   'targets': [
     {
       'target_name': 'user_agent',
       'type': '<(component)',
       'defines': [
         'WEBKIT_USER_AGENT_IMPLEMENTATION',
       ],
       'dependencies': [
         '<(DEPTH)/base/base.gyp:base',
         '<(DEPTH)/base/base.gyp:base_i18n',
@@ skipping 28 matching lines @@
       'targets': [
         {
           'target_name': 'webkit_version',
           'type': 'none',
           'actions': [
             {
               'action_name': 'webkit_version',
               'inputs': [
                 '<(script)',
                 '../../build/util/lastchange.py',  # Used by the script.
-                # This depends on the svn revision of webkit_src_dir but does
+                # This depends on the svn revision of third_party/WebKit but does
                 # not list it as a dependency.  Incremental builds will have
                 # the wrong WEBKIT_SVN_REVISION.
               ],
               'outputs': [
                 '<(SHARED_INTERMEDIATE_DIR)/webkit_version.h',
               ],
-              'action': ['python', '<(script)', '<(webkit_src_dir)',
+              'action': ['python', '<(script)', '../../third_party/WebKit/Source',
                          '<(SHARED_INTERMEDIATE_DIR)'],
               'variables': {
                 'script': '../build/webkit_version.py',
               },
             },
           ],
           'direct_dependent_settings': {
             'include_dirs': [
               '<(SHARED_INTERMEDIATE_DIR)',
             ],
           },
           # Dependents may rely on files generated by this target or one of its
           # own hard dependencies.
           'hard_dependency': 1,
         },
       ],
     }],
   ],
 }