Add logging to `chromium` wrapper
Add logging to `chromium` wrapper

If `$browser_debug` is non-empty, log the arguments and process tree to
`~/browser.log`.  Trying to figure out why I'm getting random new
Chromium windows on one machine.

benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles