For a few month after I did a fresh install of Archlinux, I found that when I try to click a link inside any application, it will call google chrome. So, I decide to fix it today. It actually easy. We can set our default browser with xdg-mime which is owned by xdg-utils.
What I did
We can set out default browser with these commands:
$ xdg-mime default firefox.desktop x-scheme-handler/http
And for https:
$ xdg-mime default firefox.desktop x-scheme-handler/https