I have been using chromium as my primary browser. Unfortunately I have been using some adobe air twitter clients, and they ignore my preferred browser setting.
I found this page: http://blog.andreaolivato.net/open-source/change-adobe-air-apps-default-browser.html.
I followed this except my link pointed to chromium-browser, and the file was simply “/opt/Adobe AIR/Versions/1.0/libCore.so”.