Debian Google Chrome

vi /etc/apt/sources.list.d/google-chrome.list
deb http://dl.google.com/linux/deb/ stable main
wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add -
apt-get update
apt-get install google-chrome-stable

Google Chrome can not be run as root
mkdir /home/chrome
chmod 777 /home/chrome
vi /usr/share/applications/google-chrome.desktop
[Desktop Entry]
Exec=/opt/google/chrome/google-chrome %U --user-data-dir=/home/chrome
Applications Menu - Settings - Preferred Applications, select google-chrome
vi ~/.local/share/xfce4/helpers/custom-WebBrowser.desktop
X-XFCE-Commands=/opt/google/chrome/google-chrome --user-data-dir=/home/chrome
Google Chrome isn't your default browser. Don't ask again.

I saw in my programs properties they have a "%u" in the end of the command, what does this do?
e.g. My Chrome have the command: /opt/google/chrome/google-chrome %U for what this %u is used here?

When you associate a file with a command, you can call this command with several arguments. %u simply means that the file name should go there. It is useful so you can put arguments after the filename. There are several other flags you can use.

http://superuser.com/questions/138433/what-is-the-u-command-in-all-my-programs-command