STR: 1. Open Firefox with an clean profile. 2. Try entering a pre-populated site (see https://hg.mozilla.org/mozilla-central/rev/9762f34b30a4) in urlbar. Actual results: Only the entered host and search suggestions, no pre-populated sites appears until I press space bar or backspace key. In addition, I did not see the pre-populated sites hint in Fx55b1, this is expected?
the feature is only enabled in Nightly for now. http://searchfox.org/mozilla-central/rev/20d16dadd336e0c6b97e3e19dc4ff907744b5734/modules/libpref/init/all.js#1115 Also, maybe there's some misunderstanding on what you are expecting. Could you please provide more specific steps about what you enter and what you see?
I noticed my understanding was wrong, the pre-populated site was automatically filled in to the address bar instead of the suggestions. I think this is intrusive and confusing for populate it to address bar (like the host visited, and no pre-filled title) rather than the suggestions.