This is about as ad-hoc as it gets, but then again, what we want
is probably as ad-hoc as it gets.
All URL boxes I know of double as search bars, and not adding
automatic spaces there sucks (e.g. in Chrome URL bar).
And in other boxes actually you don't want to add a space if
it looks like a URL. QSB isn't even a search box, and it behaves
like this.

So I think this is actually the right answer to the problem.

Bug: 7062925
Change-Id: Ib09472b34644fd5bf2dc84bb97cedeeba28bcd02