Provide skeleton for ChromeVox next.

chrome/browser/resources/chromeos/chromevox_next/chromevox2/injected/injected.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.
+
+/**
+ * @fileoverview The entry point for all ChromeVox2 related code for the
+ * injected content script.
+ * This script will temporarily forward any events we need during the
+ * ChromeVox/ChromeVox2 timeframe where extension APIs do not exist (e.g.
+ * keyboard events).
+ */
+
+/** namespace */
+var cvox2 = function() {};
+
+var port = chrome.extension.connect({name: 'chromevox2'});
+document.body.addEventListener('keydown', function(evt) {
+  port.postMessage({keydown: evt.keyCode});
+}, true);