How can I get chromium-browser to run fullscreen (not kiosk) in 12.04?

For people finding this now, you can start Chromium fullscreen from the command line by executing:

chromium-browser --app=http://example.com --start-fullscreen

Tested on Ubuntu 14.04 LTS

What about using xdtool http://manpages.ubuntu.com/manpages/lucid/man1/xdotool.1.html

xdotool key F11

this will work for any kind of standard focused window. Include it into start-up script.

don't have xdotool?

sudo apt-get install xdotool

in combination with --start-maximized (which does not do F11, just maximized window) on command line can fulfil your needs

shell script should make the job

chromium-browser --start-maximized
sleep 5
xdotool key F11

Firefox differs only in -fullscreen command line option. The option for F11 mode is missing as well. But consider to use Firefox and Rkiosk extension https://addons.mozilla.org/en-US/firefox/addon/r-kiosk/?src=search or the Fullscreen extension https://addons.mozilla.org/en-US/firefox/addon/full-fullscreen/

If the script stucks at chromium-browser invocation - add a & at the end:

chromium-browser --start-maximized &
...

Based on this and other sources, you could try the following, with good chances of success :-)

cp /usr/share/applications/chromium-browser.desktop ~/.local/share/applications/chromium-browser.desktop
nano ~/.local/share/applications/chromium-browser.desktop 

(you may alternatively want to use gksu and the editor of your choosing)

Now, simply add -start-maximized to the line saying exec in chromium-browser.desktop, save and you're done.