When a user wants to changes her password, if we don't work properly to help her fill her old password and remember her new password, it can be a big disappointment. Password change flows are unique: * Password change usually requires the user to her enter old password first, either on the same page that she chooses her new password, but sometimes on a different one. * Password change flows vary in the number of password fields that appear simultaneously. It can range between one and three. * When two password fields appear simultaneously, we need to distinguish whether each field is asking for the user's old password or new password (e.g., a confirmation). Some of the new autocomplete options could help with this, if the site supports them. * Signup flows sometimes have two password fields, so we need to distinguish password change from signup. * In a password change flow, the user rarely enters her username, so we need a way to associate a username with the captured new password.