I was able to get what, in my opinion, is the working version of Smart Lock, which allows me to save login credentials for Facebook.
API FB . , , , . :
Credential credential = new Credential.Builder(user.getEmail())
.setAccountType(IdentityProviders.FACEBOOK)
.setName(user.getName())
.build();
API Facebook, , SDK Facebook.
FB passwords.google.com. " Facebook".