google app engine - Can't connect to localhost from Chrome extension

Question

I am working on a Chrome extension that tracks time, and uses Google App Engine for the backend.

For testing, I'm trying to connect a local version of the extension to a local version of the App Engine app. When I try to send a POST request, I'm getting:

XMLHttpRequest cannot load http://localhost:8080/report. Origin chrome-extension://mbndmimplohfkkcincjodnfpaapbbmei is not allowed by Access-Control-Allow-Origin.

But it works when I change the URL so that it posts to the appspot.com URL.

What is the Access-Control-Allow-Origin, and why is it stopping me from getting results from localhost?

Answer 1

Waitting for answers