Nightly 76.0a1 (2020-04-04)
macOS 10.15.4

STR:
1.) Open a Private Window
2.) Visit a page
3.) Focus the Address Bar

Result: No Top site items/No Recently visited items are shown in Address Bar (probabaly okay, because this is an Private Mode Window)

4.) But now clear the Address Bar

Result: Top SItes items/Recently visited items are shown in Address Bar

Not sure if this is intended. But this feels inconsistent. Maybe they shouldn't be shown at all in Private Mode or show them also when focussing the Address Bar.

Thanks.

Depending on the result of bug 1628997, we may or may not want to fix this...

For now let's fix this so the result is consistent, then we'll decide what to do for bug 1628997 and we can eventually undo this.

Depends on D73279

The problem is distinguishing an effective empty search (the user types a space) from a text removal bringing to an empty search.
The patch I made also disallowed effective empty searches, and it's unclear what the behavior should be if openViewOnFocus is disabled.
In the new world where the pref states "don't show Top Sites", it would be easier, we just don't show anything for an empty search.
So the expected outcome of browser/components/urlbar/tests/browser/browser_empty_search.js is unclear
And there is also https://searchfox.org/mozilla-central/rev/7fd1c1c34923ece7ad8c822bee062dd0491d64dc/browser/components/extensions/test/browser/browser_ext_urlbar.js#235-236

This is a lot more complicate than expected without the final pref.

https://hg.mozilla.org/mozilla-central/rev/ab17874438ee