Prepare ChromeVox for webstore release.

chrome/browser/resources/chromeos/chromevox/cvox2/background/stubs.js

+// Copyright 2016 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 Installs stubs for unsupported api's on some platforms. Define
+ * the stubs here and require Stubs in the calling file.
+ */
+
+goog.provide('Stubs');
+
+goog.require('cvox.ChromeVox');
+
+/** Initializes this module. */
+Stubs.init = function() {
+  // These api's throw for non-Chrome OS.
+  if (!cvox.ChromeVox.isChromeOS) {
+    chrome.accessibilityPrivate.onAccessibilityGesture = {};
+    chrome.accessibilityPrivate.onAccessibilityGesture.addListener =
+        function() {};
+    chrome.accessibilityPrivate.setFocusRing = function() {};
+    chrome.accessibilityPrivate.setKeyboardListener = function() {};
+  }
+
+  // This api throws on Mac.
+  if (cvox.ChromeVox.isMac) {
+    chrome.automation.getDesktop = function() {};
+  }
+
+  // Missing api's until 53.
+  if (!chrome.automation.NameFromType) {
+    chrome.automation['NameFromType'] = {};
+    chrome.automation['DescriptionFromType'] = {};
+  }
+};
+
+Stubs.init();