This is probably going to require modifying the Gaia marketplace preinstalled app as well.
Should be an easy one line fix to your manifest though - you just need to set orientation to portrait in the app manifest.
Here's the related PRs.
Nit on process (for how Gaia pull requests work) - you might want to split the Gaia piece into a separate bug, attach a HTML attachment pointing to your github pull request, and ask for reviewer from a Gaia peer (fabrice or vivien are good candidates in this case).
(In reply to Jason Smith [:jsmith] from comment #5)
> Nit on process (for how Gaia pull requests work) - you might want to split
> the Gaia piece into a separate bug, attach a HTML attachment pointing to
> your github pull request, and ask for reviewer from a Gaia peer (fabrice or
> vivien are good candidates in this case).
You'll also want the nom the associated bug for approval v1 to get this on v1-train.
Dumb question: why do we want to lock the marketplace into portrait?
(In reply to Kumar McMillan [:kumar] from comment #7)
> Dumb question: why do we want to lock the marketplace into portrait?
Because we don't have landscape designs. It's not a trivial effort to make those, and then implement that - and also not a high priority. So instead of letting it look bad until we do landscape we just won't allow it :P
Added to Fireplace: https://github.com/mozilla/fireplace/commit/d75fad2c1
Per talking with mushi and fabrice - let's actually go with portrait-primary here, not portrait only.
Updated to portrait-primary in Fireplace: https://github.com/mozilla/fireplace/commit/59330dcda6cf3e6020778b0c0b775ee9c633b728
Awaiting 846831 to land.
Looks like that landed.