1916843 - Check merge-warnings work correctly in oauth flows.

Status: NEW

(Firefox :: Firefox Accounts, defect, P2)

Description

[Mark Hammond [:markh] [:mhammond]]

When we get a "login" webchannel message, we record the last user connected for use by future merge-warnings. However, we only record it when the user is verified. This is the code

However, in an account creation flow, we expect this login message before the account is verified. Once we get the final oauth_login message we do know the account was verified - but the code handling that (just a few lines below the above) doesn't attempt to report that last user.

There's a reasonable chance something else calls this instead - which kinda implies to me that the first call in login might not strictly be necessary. Regardless, this but is primarily to assure ourselves there are no login flows which do not call setPreviousAccountNameHashPref, because if that's not called, the next signin of a different user will not show a merge warning.