About debugging chrome extension

Nowadays you have to install a Chrome extension to allow you to inspect the view of a page, specifically the Develop and Debug Chrome Apps & Extensions

background.js is loaded in the background. To inspect it visit chrome://extensions, find the loaded extension, and "inspect active views" for the background script.

Edit

Below is a screenshot of the chrome extensions page. A click on the link background page opens the background page for this extension.

Additional information

EDIT 2020

Here is how you can see the content scripts and debug,