Synchronize settings with Firefox Sync
Copied and edited from Tab Center Redux Github page.
Particularly the custom CSS is likely to be nontrivial to setup again.
browser.storage.sync
is limited to 8kB by record, and it seems 200 lines ≃ 6kB so it should be enough (but we should take into account possible overflow).
I think we also need to handle some some sort of migration from browser.storage.local
to browser.storage.sync
to avoid losing existing settings after the change.