Code review comment for lp:~brandontschaefer/mir/add-mir-chrome-none

It would make sense to mention why we need this. Also, this should have been the first element in the enum, is it too late for that? If it is, do you want to assign some value to it to leave a gap in case you need other chrome values? (i.e.

mir_shell_chrome_normal,
mir_shell_chrome_low,
mir_shell_chrome_none = 1000

or some such thing?)