Added more typechecking functions and unit tests for existing code.

remoting/webapp/crd/js/video_frame_recorder.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
  * Class implement the video frame recorder extension client.
  */
 
 'use strict';
@@ skipping 45 matching lines @@
  * @param {string} type Type of extension message.
  * @param {Object} message The parsed extension message data.
  * @return {boolean}
  */
 remoting.VideoFrameRecorder.prototype.handleMessage =
     function(type, message) {
   if (type != 'video-recorder') {
     return false;
   }
 
-  var messageType = getStringAttr(message, 'type');
-  var messageData = getStringAttr(message, 'data');
+  var messageType = base.getStringAttr(message, 'type');
+  var messageData = base.getStringAttr(message, 'data');
 
   if (messageType == 'next-frame-reply') {
     if (!this.fileWriter_) {
       console.log("Received frame but have no writer");
       return true;
     }
     if (!messageData) {
       console.log("Finished receiving frames");
       this.fileWriter_ = null;
       return true;
@@ skipping 64 matching lines @@
 remoting.VideoFrameRecorder.prototype.onWriteComplete_ = function(e) {
   console.log("Video frame write complete");
   this.fetchNextFrame_();
 }
 
 remoting.VideoFrameRecorder.prototype.fetchNextFrame_ = function() {
   console.log("Request next video frame");
   var data = { type: 'next-frame' }
   this.plugin_.sendClientMessage('video-recorder', JSON.stringify(data));
 }