Check for warnings when loading extensions in browser tests.

chrome/test/data/extensions/api_test/webnavigation/test_iframe.js

Index: chrome/test/data/extensions/api_test/webnavigation/test_iframe.js
diff --git a/chrome/test/data/extensions/api_test/webnavigation/test_iframe.js b/chrome/test/data/extensions/api_test/webnavigation/test_iframe.js
index af723054b4b435fc7303da73307da20a9a483984..b500bebc472b1744f00db19d5a953fc6506f3c69 100644
--- a/chrome/test/data/extensions/api_test/webnavigation/test_iframe.js
+++ b/chrome/test/data/extensions/api_test/webnavigation/test_iframe.js
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-function runTests() {
+onload = function() {
   var getURL = chrome.extension.getURL;
   chrome.tabs.create({"url": "about:blank"}, function(tab) {
     var tabId = tab.id;
@@ -349,4 +349,4 @@ function runTests() {
       },
     ]);
   });
-}
+};