When Chrome tries to figure out, which text field of a password form is the username, it picks one and stores the rest in PasswordForm::other_possible_usernames. This is true currently for the old form parser living in components/autofill/content/renderer/password_form_conversion_utils.cc.

However, for simplicity, the new parser (components/password_manager/core/browser/form_parsing/form_parser.cc) will put all usernames in that list, including the one Chrome picked as the most likely username.

To avoid confusion, PasswordForm::other_possible_usernames shall be renamed to all_possible_usernames in the future.

This should not happen before the old parser is gone.