I am learning chrome extension by example. Here is the example I currently learning: http://www.chrome-extensions.net/extensions/mappy/
There are three JavaScript fi
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.
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,
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