As discussed at https://bugzilla.mozilla.org/show_bug.cgi?id=1321303#c130, there's an issue with the current implementation of password removal if a user has a Master Password set and chooses not to enter it when this API attempts to clear passwords. Removing the call to getAllLogins from ext-browsingData.js and replacing it with a call to removeAllLogins will fix this, but in order to do that we'll need removeAllLogins to support passing in a "since" date.
Comment on attachment 8856193 [details] Bug 1332613 - Add support for removeAllLogins to take an optional parameter 'since'; https://reviewboard.mozilla.org/r/128132/#review131390 Thomas, thanks for doing this, but this patch should be attached to bug 1332611, which was opened for that purpose, and I wouldn't be the one to review the changes, it would be someone responsible for the nsILoginManager code.
Comment on attachment 8856194 [details] Bug 1332613 - Remove the call to getAllLogins from browsingData.remove(passwords) in favor of calling removeAllLogins(since); https://reviewboard.mozilla.org/r/128134/#review131392 This looks good, Thomas, but its review will have to wait for bug 1332611 to land, so I'm removing my review flag for now. Please re-flag me for review once the changes for bug 1332611 land, changing the behaviour of removeAllLogins.