Add an extensions keep-alive client.

extensions/test/data/keep_alive_client_unittest.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.
+
+/**
+ * Unit tests for the keep-alive client.
+ *
+ * They are launched by extensions/renderer/mojo/keep_alive_client_unittest.cc.
+ */
+
+var test = require('test').binding;
+var unittestBindings = require('test_environment_specific_bindings');
+var utils = require('utils');
+
+var shouldSucceed;
+
+// We need to set custom bindings for a real API and serial.getDevices has a
+// simple signature.
+var binding = require('binding').Binding.create('serial');
+binding.registerCustomHook(function(bindingsAPI) {
+  bindingsAPI.apiFunctions.setHandleRequestWithPromise('getDevices',
+      function() {
+    if (shouldSucceed)
+      return Promise.resolve([]);
+    else
+      return Promise.reject();
+  });
+});
+var apiFunction = binding.generate().getDevices;
+
+unittestBindings.exportTests([
+  // Test that a keep alive is created and destroyed for a successful API call.
+  function testKeepAliveWithSuccessfulCall() {
+    shouldSucceed = true;
+    utils.promise(apiFunction).then(test.succeed, test.fail);
+  },
+
+  // Test that a keep alive is created and destroyed for an unsuccessful API
+  // call.
+  function testKeepAliveWithError() {
+    shouldSucceed = false;
+    utils.promise(apiFunction).then(test.fail, test.succeed);
+  },
+], test.runTests, exports);