Move the chromeHidden.toJSON paranoia out of event.js and into json.js, a new

chrome/chrome_tests_unit.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.
 {
   'targets': [
     {
       # This target contains mocks and test utilities that don't belong in
       # production libraries but are used by more than one test executable.
       'target_name': 'test_support_common',
       'type': 'static_library',
@@ skipping 1572 matching lines @@
         'common/web_apps_unittest.cc',
         'common/worker_thread_ticker_unittest.cc',
         'common/zip_reader_unittest.cc',
         'common/zip_unittest.cc',
         'nacl/nacl_ipc_adapter_unittest.cc',
         'nacl/nacl_validation_query_unittest.cc',
         'renderer/chrome_content_renderer_client_unittest.cc',
         'renderer/content_settings_observer_unittest.cc',
         'renderer/extensions/chrome_v8_context_set_unittest.cc',
         'renderer/extensions/event_unittest.cc',
+        'renderer/extensions/json_js_unittest.cc',
         'renderer/extensions/json_schema_unittest.cc',
         'renderer/extensions/module_system_unittest.cc',
         'renderer/net/predictor_queue_unittest.cc',
         'renderer/net/renderer_predictor_unittest.cc',
         'renderer/plugins/plugin_uma_unittest.cc',
         'renderer/prerender/prerender_dispatcher_unittest.cc',
         'renderer/safe_browsing/features_unittest.cc',
         'renderer/safe_browsing/murmurhash3_util_unittest.cc',
         'renderer/safe_browsing/phishing_term_feature_extractor_unittest.cc',
         'renderer/safe_browsing/phishing_url_feature_extractor_unittest.cc',
@@ skipping 783 matching lines @@
               # more details.
               'DebugInformationFormat': '3',
               'ProgramDataBaseFileName': '<(PRODUCT_DIR)/unit_tests.exe.pdb',
             },
           },
         },
       ],
     }],
   ],  # 'conditions'
 }