[Extensions Bindings] Return result from event dispatch

chrome/test/data/extensions/api_test/native_bindings/extension/background.js

 // Copyright 2016 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.
 
 if (!chrome || !chrome.test)
   throw new Error('chrome.test is undefined');
 
 var portNumber;
 
 // This is a good end-to-end test for two reasons. The first is obvious - it
@@ skipping 42 matching lines @@
       });
     });
     Promise.all([createdEvent, createdCallback]).then(res => {
       chrome.test.assertEq(2, res.length);
       chrome.test.assertEq(res[0], res[1]);
       chrome.test.succeed();
     });
   },
   function testMessaging() {
     var tabId;
+
     var createPort = function() {
       chrome.test.assertTrue(!!tabId);
       var port = chrome.tabs.connect(tabId);
       chrome.test.assertTrue(!!port, 'Port does not exist');
       port.onMessage.addListener(message => {
         chrome.test.assertEq('content script', message);
         port.disconnect();
-        chrome.test.succeed();
+        chrome.tabs.sendMessage(tabId, 'async bounce', function(response) {
+          chrome.test.assertEq('bounced', response);
+          chrome.test.succeed();
+        });
       });
       port.postMessage('background page');
     };
 
-    chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
+    chrome.runtime.onMessage.addListener(function listener(
+        message, sender, sendResponse) {
       chrome.test.assertEq('startFlow', message);
       createPort();
       sendResponse('started');
+      chrome.runtime.onMessage.removeListener(listener);
     });
+
     var url = 'http://localhost:' + portNumber +
               '/native_bindings/extension/messaging_test.html';
     chrome.tabs.create({url: url}, function(tab) {
       chrome.test.assertNoLastError();
       chrome.test.assertTrue(!!tab);
       chrome.test.assertTrue(!!tab.id && tab.id >= 0);
       tabId = tab.id;
     });
   },
   function castStreaming() {
@@ skipping 227 matching lines @@
     });
   },
 ];
 
 chrome.test.getConfig(config => {
   chrome.test.assertTrue(!!config, 'config does not exist');
   chrome.test.assertTrue(!!config.testServer, 'testServer does not exist');
   portNumber = config.testServer.port;
   chrome.test.runTests(tests);
 });