Fixed and reenabled the flaky test "WebViewAPITest.TestAutosizeAfterNavigation".

chrome/test/data/extensions/platform_apps/web_view/shim/main.js

 // Copyright (c) 2012 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 util = {};
 var embedder = {};
 embedder.baseGuestURL = '';
 embedder.emptyGuestURL = '';
 embedder.windowOpenGuestURL = '';
 embedder.noReferrerGuestURL = '';
@@ skipping 160 matching lines @@
 function testAutosizeBeforeNavigation() {
   var webview = document.createElement('webview');
 
   webview.setAttribute('autosize', 'true');
   webview.setAttribute('minwidth', 200);
   webview.setAttribute('maxwidth', 210);
   webview.setAttribute('minheight', 100);
   webview.setAttribute('maxheight', 110);
 
   webview.addEventListener('sizechanged', function(e) {
-    embedder.test.assertEq(0, e.oldWidth);
-    embedder.test.assertEq(0, e.oldHeight);
+    // The old size should be the default size of the webview, which at the time
+    // of writing this comment is 300 x 300, but is not important to this test
+    // and could change in the future, so it is not checked here.
     embedder.test.assertTrue(e.newWidth >= 200 && e.newWidth <= 210);
     embedder.test.assertTrue(e.newHeight >= 100 && e.newHeight <= 110);
     embedder.test.succeed();
   });
 
   webview.setAttribute('src', 'data:text/html,webview test sizechanged event');
   document.body.appendChild(webview);
 }
 
 // Makes sure 'sizechanged' event is fired only if autosize attribute is
@@ skipping 1940 matching lines @@
   'testFindAPI_findupdate': testFindAPI,
   'testLoadDataAPI': testLoadDataAPI
 };
 
 onload = function() {
   chrome.test.getConfig(function(config) {
     embedder.setUp_(config);
     chrome.test.sendMessage("Launched");
   });
 };