Switch platform apps from a declarative launch container to handling an onLaunched event.

chrome/test/data/extensions/platform_apps/context_menu/test.js

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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.
 
-function onclick(info) {
-}
-
-window.onload = function() {
-  chrome.contextMenus.create({"title":"Extension Item 1",
-                              "onclick": onclick}, function() {
-    if (!chrome.extension.lastError) {
-      chrome.test.sendMessage("created item");
-    }
-  });
-};
+chrome.experimental.app.onLaunched.addListener(function() {
+  chrome.contextMenus.create({
+        title: 'Extension Item 1',
+        onclick: function() {}
+      },
+      function() {
+        chrome.windows.create({
+            url: 'main.html',
+            type: 'shell'
+        });
+      });
+});