Refactor the implementation of the webNavigation extension API.

chrome/test/data/extensions/api_test/executescript/http204/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.
 
 var config;
 var MAIN_HOST = 'b.com';
 var OTHER_HOST = 'c.com';
 
 var DOMContentLoadedEventsInFrame = [];
 
@@ skipping 230 matching lines @@
     },
 
     function verifyCrossOriginManifestAfterCrossOrigin204() {
       checkManifestScriptsAfter204Navigation(tabId);
     },
   ]);
 }
 
 // Navigates to a page that navigates to a 204 page via a script.
 function navigateToFrameAndWaitUntil204Loaded(tabId, hostname, hostname204) {
-  // If the child frame's origin differs from the parent frame's origin, and
-  // site isolation is enabled, then two onErrorOccurred events are expected:
-  // 1. onErrorOccurred for a process swap of the initial frame.
-  // 2. onErrorOccurred for the failed provisional load.
-  // TODO(robwu): Remove this work-around when the navigation is immediately
-  // handled in the right process (so that a process swap is not needed).
-  var expectTwoErrors = MAIN_HOST !== hostname && config.isolateExtensions;
   var doneListening = chrome.test.listenForever(
       chrome.webNavigation.onErrorOccurred,
       function(details) {
         if (details.tabId === tabId && details.frameId > 0) {
-          if (expectTwoErrors) {
-            // |url| is the initial URL of the iframe, declared below.
-            chrome.test.assertEq(url, details.url);
-            expectTwoErrors = false;
-            return;
-          }
           chrome.test.assertTrue(details.url.includes('page204.html'),
               'frame URL should be page204.html, but was ' + details.url);
           doneListening();
         }
       });
 
   var url = 'http://' + hostname + ':' + config.testServer.port +
     '/extensions/api_test/executescript/http204/navigate_to_204.html?' +
     hostname204;
 
@@ skipping 20 matching lines @@
 
     // Child frame.
     chrome.test.assertEq([
         // Should run the content scripts even after a navigation to 204.
         [1, 1],
         // Should not inject non-matching scripts.
         [null, null],
     ], results[1]);
   }));
 }