[boken]

I'm not sure how this would pose a problem. I'm not the parent commenter, but I don't typically go to Google to search for sites I frequent. It would be such an odd thing to do—granted that I know the URL—that I would be forced to consider what I was doing even more vividly than if I had to type the URL out.

Unless you mean the search bar?

  browser.search.suggest.enabled = false

Or, if you mean that you'd like to have autocomplete on for searches, just leave the default:

  browser.search.suggest.enabled = true

This does not affect the URL bar.