This is the flip-the-switch ticket for FxA sign in on the web in Fennec Nightly. I expect to throw the switch at the beginning of the Fennec 44 cycle, get some testing, and then throw it near the middle of the Aurora 43 cycle.

Bug 1205734 - Enable web-based Firefox Accounts UI in Fennec Nightly. r=me

vivek: if you're working on this code, you'll need a commit like the one in the review above to flip the switch locally.

kbrosnan, QA team: this ticket turns on an entirely new web-based UI for sign up/sign in to Firefox Accounts. It could use some careful testing. Scenarios I would appreciate you testing: a) Fresh Fennec, "Sign in to Sync" during the First Run experience. b) Fresh Fennec, don't sign in during First Run, navigate to Settings > Sync and "sign up". I'd appreciate hearing about problems and delays in the "verification" flow; most of these are known, but we shouldn't regress too hard. c) Same, but instead of "sign up" for a new account, "sign in" to an existing account. d) Connect Fennec. Change the account password on a different device. (Desktop.) Force a Sync in Fennec; observe "you need to connect" notification. Re-connect using the web interface. Verify that Sync is working correctly. e) Connect Fennec. Go to Sync > Settings and "Manage account". Change the Avatar; verify that you see a fresh avatar in the Sync > Settings menu. f) Connect Fennec. Go to Sync > Settings and "Manage account". Change the account password. Verify that Sync continues to work correctly. On a different device, verify that you need to update the password for Sync to continue. g) Remove any existing Accounts. Put your device in Airplane mode. Go to Sync > Settings. You should see an Internet connection required screen in about:accounts. h) Start Guest Browsing. Navigate to "about:accounts" manually. You should see a "you're restricted" screen. i) Connect Fennec to an account. Remove that Account from Sync > Settings and the menu item. Try to connect Fennec to an account with a *different* email address. You should see an "are you sure" dialog, but you should be able to both "opt out" (and not connect) or "opt in" and connect to the new account. I'm sure there are more, but I can't think of them just now.

Redirecting to Ioana as I'll be on PTO after this week.

Verified as fixed on latest Nightly 44.0a1 10-19-2015 on Sony Xperia Z2 (Android 5.0.2)