Split out the extensions gin::Runner implementation into a separate class.

extensions/extensions.gyp

 # Copyright 2013 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 1270 matching lines @@
         'renderer/api_test_base_unittest.cc',
         'renderer/event_unittest.cc',
         'renderer/json_schema_unittest.cc',
         'renderer/mojo/keep_alive_client_unittest.cc',
         'renderer/messaging_utils_unittest.cc',
         'renderer/module_system_test.cc',
         'renderer/module_system_test.h',
         'renderer/module_system_unittest.cc',
         'renderer/safe_builtins_unittest.cc',
         'renderer/script_context_set_unittest.cc',
+        'renderer/script_context_unittest.cc',
         'renderer/utils_unittest.cc',
         'test/extensions_unittests_main.cc',
       ],
       # Disable c4267 warnings until we fix size_t to int truncations.
       'msvs_disabled_warnings': [ 4267, ],
       'conditions': [
         ['OS=="win" and win_use_allocator_shim==1', {
           'dependencies': [
             '../base/allocator/allocator.gyp:allocator',
           ],
         }],
       ],
     },
   ]
 }