Google Chrome is set as the default browser, however it opens links in Firefox, which is undesired.
How to make org-mode to open links in
I also had this problem when exporting org files to html. It would use firefox instead of chromium-browser. I fixed it by customizing org-file-apps (which for some reason had been set to open xhtml and html files with firefox).
I now have an entry for extension \.x?html?\' with command set to the Lisp form: (browse-url file)