Pass error messages from native messaging to web-app.

remoting/webapp/crd/js/it2me_host_facade.js

Index: remoting/webapp/crd/js/it2me_host_facade.js
diff --git a/remoting/webapp/crd/js/it2me_host_facade.js b/remoting/webapp/crd/js/it2me_host_facade.js
index 64428f34813453cbf0a31926d47f10d0928f9b2b..c9167c84905941f460c73c757468cea0ec2b06db 100644
--- a/remoting/webapp/crd/js/it2me_host_facade.js
+++ b/remoting/webapp/crd/js/it2me_host_facade.js
@@ -61,6 +61,11 @@ remoting.It2MeHostFacade = function() {
 
   /** @private {?function(boolean):void} */
   this.onNatPolicyChanged_ = function() {};
+
+  /** @private */
+  this.debugMessageHandler_ =
+      new remoting.NativeMessageHostDebugMessageHandler();
+
 };
 
 remoting.It2MeHostFacade.prototype.dispose = function() {
@@ -208,6 +213,10 @@ remoting.It2MeHostFacade.prototype.getClient = function() {
  */
 remoting.It2MeHostFacade.prototype.onIncomingMessage_ =
     function(message) {
+  if (this.debugMessageHandler_.handleMessage(message)) {
+    return;
+  }
+
   var type = base.getStringAttr(message, 'type');
 
   switch (type) {