How to minify my google chrome extension's javascript files

I am finished up with my google chrome extension development. Now its time to deploy on google chrome extension dashboard. But the problem is How do I minify my javascript files (background.js and content.js). I can use online tools available but they do one file at a time and do not consider the dependency on other javascript file.

For example, message passing between background.js and content.js is done by a key value, which tells the other party that what kind of message is this. I am not sure whether chrome itself minifies my javascript file. I little illiterate here. Please help.