Add support for writing unit tests for Mojo-backed apps/extensions APIs.

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 chrome = requireNative('chrome').GetChrome();
+var environmentSpecificBindings = require('test_environment_specific_bindings');
 var GetExtensionAPIDefinitionsForTest =
     requireNative('apiDefinitions').GetExtensionAPIDefinitionsForTest;
-var GetAvailability = requireNative('v8_context').GetAvailability;
 var GetAPIFeatures = requireNative('test_features').GetAPIFeatures;
 var uncaughtExceptionHandler = require('uncaught_exception_handler');
 var userGestures = requireNative('user_gestures');
 
 var RunWithNativesEnabledModuleSystem =
     requireNative('v8_context').RunWithNativesEnabledModuleSystem;
 
 binding.registerCustomHook(function(api) {
   var chromeTest = api.compiledApi;
   var apiFunctions = api.apiFunctions;
 
   chromeTest.tests = chromeTest.tests || [];
 
   var currentTest = null;
   var lastTest = null;
   var testsFailed = 0;
   var testCount = 1;
   var failureException = 'chrome.test.failure';
 
   // Helper function to get around the fact that function names in javascript
   // are read-only, and you can't assign one to anonymous functions.
   function testName(test) {
     return test ? (test.name || test.generatedName) : "(no test)";
   }
 
   function testDone() {
-    // Use setTimeout here to allow previous test contexts to be
-    // eligible for garbage collection.
-    setTimeout(chromeTest.runNextTest, 0);
+    environmentSpecificBindings.testDone(chromeTest.runNextTest);
   }
 
   function allTestsDone() {
     if (testsFailed == 0) {
       chromeTest.notifyPass();
     } else {
       chromeTest.notifyFail('Failed ' + testsFailed + ' of ' +
                              testCount + ' tests');
     }
   }
 
   var pendingCallbacks = 0;
 
   apiFunctions.setHandleRequest('callbackAdded', function() {
     pendingCallbacks++;
 
     var called = null;
     return function() {
       if (called != null) {
         var redundantPrefix = 'Error\n';
-        chrome.test.fail(
+        chromeTest.fail(
           'Callback has already been run. ' +
           'First call:\n' +
           $String.slice(called, redundantPrefix.length) + '\n' +
           'Second call:\n' +
           $String.slice(new Error().stack, redundantPrefix.length));
       }
       called = new Error().stack;
 
       pendingCallbacks--;
       if (pendingCallbacks == 0) {
@@ skipping 274 matching lines @@
 
   apiFunctions.setHandleRequest('runWithoutUserGesture', function(callback) {
     chromeTest.assertEq(typeof(callback), 'function');
     return userGestures.RunWithoutUserGesture(callback);
   });
 
   apiFunctions.setHandleRequest('setExceptionHandler', function(callback) {
     chromeTest.assertEq(typeof(callback), 'function');
     uncaughtExceptionHandler.setHandler(callback);
   });
+
+  environmentSpecificBindings.registerHooks(api);
 });
 
 exports.binding = binding.generate();