Added more typechecking functions and unit tests for existing code.

remoting/webapp/crd/js/cast_extension_handler.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 Description of this file.
  * Class handling interaction with the cast extension session of the Chromoting
  * host. It receives and sends extension messages from/to the host through
  * the client session. It uses the Google Cast Chrome Sender API library to
  * interact with nearby Cast receivers.
@@ skipping 75 matching lines @@
   }
   node.addEventListener('load', onLoad, false);
   node.addEventListener('error', onLoadError, false);
 };
 
 /**
  * Process Cast Extension Messages from the Chromoting host.
  * @param {string} msgString The extension message's data.
  */
 remoting.CastExtensionHandler.prototype.onMessage = function(msgString) {
-  var message = getJsonObjectFromString(msgString);
+  var message = base.getJsonObjectFromString(msgString);
 
   // Save messages to send after a session is established.
   this.messageQueue_.push(message);
   // Trigger the sending of pending messages, followed by the one just
   // received.
   if (this.session_) {
     this.sendPendingMessages_();
   }
 };
 
@@ skipping 129 matching lines @@
 /**
  * Listener invoked when a cast extension message is received from the Cast
  * device.
  * @param {string} ns The namespace of the message received.
  * @param {string} message The stringified JSON message received.
  */
 remoting.CastExtensionHandler.prototype.chromotingMessageListener =
     function(ns, message) {
   if (ns === this.kCastNamespace_) {
     try {
-        var messageObj = getJsonObjectFromString(message);
+        var messageObj = base.getJsonObjectFromString(message);
         this.sendMessageToHost_(messageObj);
     } catch (err) {
       console.error('Failed to process message from Cast device.');
     }
   } else {
     console.error("Unexpected message from Cast device.");
   }
 };
 
 /**
@@ skipping 81 matching lines @@
 };
 
 /**
  * Listener invoked when we fail to stop the receiver application.
  *
  * @param {chrome.cast.Error} error The error code.
  */
 remoting.CastExtensionHandler.prototype.onStopAppError = function(error) {
   console.error('Error Stopping App: ', error);
 };