[Extensions Bindings] Add a bridge to use current custom bindings

extensions/renderer/resources/test_custom_bindings.js

 // Copyright 2014 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.
 
 // test_custom_bindings.js
 // mini-framework for ExtensionApiTest browser tests
 
-var binding = require('binding').Binding.create('test');
+var binding = apiBridge || require('binding').Binding.create('test');
 
 var environmentSpecificBindings = require('test_environment_specific_bindings');
 var GetExtensionAPIDefinitionsForTest =
     requireNative('apiDefinitions').GetExtensionAPIDefinitionsForTest;
 var GetAPIFeatures = requireNative('test_features').GetAPIFeatures;
 var natives = requireNative('test_native_handler');
 var uncaughtExceptionHandler = require('uncaught_exception_handler');
 var userGestures = requireNative('user_gestures');
 
 var GetModuleSystem = requireNative('v8_context').GetModuleSystem;
@@ skipping 331 matching lines @@
     uncaughtExceptionHandler.setHandler(callback);
   });
 
   apiFunctions.setHandleRequest('getWakeEventPage', function() {
     return natives.GetWakeEventPage();
   });
 
   environmentSpecificBindings.registerHooks(api);
 });
 
-exports.$set('binding', binding.generate());
+if (!apiBridge)
+  exports.$set('binding', binding.generate());