Could we just revert to the old UI if we don't have any cards?

We have to find out before inflating the NTP if we have snippets or not -- would the stored snippets always be fresh enough to use for that?

Hm, that would probably break the first-run, no? When you see an NTP for the first time, we're probably not done fetching snippets yet, so you'd get the old UI.

We'd also need to be careful about cases when you have discarded all snippets etc, to prevent users from going back and forth between the UIs.

The thing is, there could be a lot of reasons why we don't show cards -- not signed in, Sync is encrypted, network error, no matching cards -- and for some of them we don't even know in advance whether that's going to be the case. Showing the new NTP UI with no cards in those cases would be suboptimal, so ideally we would just be able to fall back to the old UI.

What are the differences between old and new UI? The bookmarks / recent tabs buttons, and what else?

That, plus bugs while we work on the new NTP UI.

> What are the differences between old and new UI? The bookmarks / recent tabs buttons, and what else?

The spacing and background color are also. Besides that, differences should be related to bugs.

If the new UI is not disabled because of a flag, I think we should still use it for users where snippets are not enabled. Other experiments will rely on it, it will avoid splitting the work across both UIs, and will be consistent for all users. 

If we stay on the new UI, shouldn't hiding or showing the hint ( issue 586126 ) be the only required UI change? that would not break on FRE, sign out, etc.

Hm... I'm thinking we should make the new NTP UI nice enough that it's not a problem to show it to everyone -- I think that's basically what Nicolas is saying, right? And then we could show the hint if and only if there are cards.

Makes sense! Then I guess this is WontFix :)