Support role description in automation/ChromeVox

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

 // Copyright 2015 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 This is the low-level class that generates ChromeVox's
  * earcons. It's designed to be self-contained and not depend on the
  * rest of the code.
  */
 
@@ skipping 157 matching lines @@
  * @param {string} url The url where the sound should be fetched from.
  */
 EarconEngine.prototype.loadSound = function(name, url) {
   var request = new XMLHttpRequest();
   request.open('GET', url, true);
   request.responseType = 'arraybuffer';
 
   // Decode asynchronously.
   request.onload = (function() {
     this.context_.decodeAudioData(
-        /** @type {ArrayBuffer} */ (request.response),
+        /** @type {!ArrayBuffer} */ (request.response),
         (function(buffer) {
           this.buffers_[name] = buffer;
         }).bind(this));
   }).bind(this);
   request.send();
 };
 
 /**
  * Return an AudioNode containing the final processing that all
  * sounds go through: master volume / gain, panning, and reverb.
@@ skipping 540 matching lines @@
 
   // Clamp.
   x = Math.min(Math.max(x, 0.0), 1.0);
 
   // Map to between the negative maximum pan x position and the positive max x
   // pan position.
   x = (2 * x - 1) * EarconEngine.MAX_PAN_ABS_X_POSITION;
 
   this.masterPan = x;
 };