Making icon url for buttons in notification optional.

chrome/test/data/extensions/api_test/notifications/api/partial_update/background.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.
 
 const notifications = chrome.notifications;
 
 function arrayEquals(a, b) {
   if (a === b) return true;
   if (a == null || b == null) return false;
   if (a.length !== b.length) return false;
@@ skipping 106 matching lines @@
   var basicNotificationOptions = {
     type: "basic",
     title: "Basic title",
     message: "Basic message",
     iconUrl: red_dot,
     buttons: [{title: "Button"}]
   };
 
   // Create a notification.
   create("testId", basicNotificationOptions)
-    // Then update a few items
-    .then(function () {
-      return update("testId", {
-        title: "Changed!",
-        message: "Too late! The show ended yesterday"
-      });
-    })
-    // Then update a few more items
-    .then(function () { return update("testId", {priority:2, buttons: []}); })
-    // The test will continue in C++, checking that all the updates "took"
-    .then(chrome.test.succeed, chrome.test.fail);
+      // Then update a few items
+      .then(function() {
+        return update("testId", {
+          title: "Changed!",
+          message: "Too late! The show ended yesterday"
+        });
+      })
+      // Then update a few more items
+      .then(function() {
+        return update("testId", {priority: 2, buttons: [{title: "NewButton"}]});
+      })
+      // The test will continue in C++, checking that all the updates "took"
+      .then(chrome.test.succeed, chrome.test.fail);
 };
 
 
 chrome.test.runTests([testPartialUpdate]);