Tested with Ubuntu 12.04

Code:
sudo apt-get update
sudo apt-get install chromium-browser tor polipo
Now edit /etc/polipo/config
and add:

Code:
socksParentProxy = "localhost:9050"
diskCacheRoot = ""
disableLocalInterface=true
Now when you want to be on tor launch it with:

Code:
chromium-browser --proxy-server="127.0.0.1:8123;https=127.0.0.1:8123;
socks=127.0.0.1:8123;sock4=127.0.0.1:8123;
sock5=127.0.0.1:8123,ftp=127.0.0.1:8123" --incognito check.torproject.org
You can put that line inside a bash script or in a launcher