linux_aura: Add openbox to install-build-deps.sh

Also, remove metacity, which was left over from the last time I did
anything with trying to get a window manager better than icewm on the
bots.

BUG=308335
R=phajdan.jr@chromium.org

Review URL: https://codereview.chromium.org/26205007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229179 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229179