Offline we discussed dropping the placeholders and centering the row of items horizontally, but for that particular solution I'm not fully convinced it is better.

Is there a particular reason you want to change this (maybe related to the content additions)?

I am completely rewriting this behavior, so if a change is needed, the new behavior would be as long to implement as the old one. It is a good opportunity to make a change if one is needed.

Don't these placeholders get backfilled on the next NTP ? Whether with popular sites or with most likely ? I am not sure when do we end up with a grey square like this.

I am not sure I understand. The placeholders appear when you have the popular sites and you delete some of them for example.
If you visit some pages, they get filled.

I see. My bad. So this case is only when the user hasn't visited enough sites yet, is signed out, and deletes some popular sites tiles. 

I think it is cleaner to not have anything at all personally. No grey squares and no change in layout. 

I am not sure the signed in/out change anything (the user would need to have not enough sites visited on all devices), but yes this should be the only use cases.

Talked with Gauthier offline and apparently this isn't a copy-and-paste type of reimplementation and the current grey cell behavior is a lot of work to redo. Considering Android doesn't use the grey cell behavior, you can remove it, but keep the layout as is (i.e. don't center <x cells).

Thanks, we go as pete said in #7.