Offline optional?

Nobody has claimed this yet.

For the app we built for [The Economist](https://app.economist.com/qatool) [click "Enable" next to enable unsupported devices and then click go to app then "Continue without registering"] we [sometimes] made the offline experience optional (and if you click yes it runs a rudimentary test to try to guess how much space it has available - and will bail if it determines there isn't enough - users can try again via the UI under "My Account").


The reasons are:
1. there are a lot of browsers that request permission from the user to grant offline storage, which range from nasty to hideous and we wanted to give users a little warning that it was about to happen... With apologies to the Mozilla team... 
2. On IE the user has the ability to set how much storage it can grant to offline websites - and I think it lets you go as low as 1mb... which just isn't enough for our application to offer any meaningful offline experience. And in those cases we wanted our application to _gracefully degrade_ to being a website, even if it didn't function offline.

So I guess the question I'm asking here is:-
- Are there plans for Chrome/Firefox have any "Would you like to allow this website to install a ServiceWorker?" type UI? [If no then perhaps there is less reason to do this]
- Do we want to architect the app so that it would be easy to make the offline experience optional? (I guess TweetDeck doesn't have as much of a concept of 'drive-by users' in the same way a newspaper has in terms of a number of users who have just come to read a single article)

The issue names no files, tests, or entry point. Start by reviewing the prototype's current offline flow and browser storage and permission behavior, then define whether offline can be opt-in with graceful fallback and record the resulting architectural decision.

Written by the indexing model from the issue text.