Smart Lock does not retrieve saved Facebook credential

[wuman]

The current implementation (as of commit c9962e7) uses the CredentialsAPI class to request for saved credentials in Smart Lock. However, it does not appear to retrieve any other account types other than Google. The end result is that a saved Facebook credential cannot be retrieved for further auto sign-in.

This can seemingly be fixed by requiring the CredentialsAPI class depend on a list of account types and then requesting for the credentials of those account types in CredentialsAPI#requestCredentials():

public void requestCredentials(final boolean shouldResolve, boolean onlyPasswords) {
    CredentialRequest.Builder crBuilder = new CredentialRequest.Builder().setPasswordLoginSupported(true);

    if (!onlyPasswords) {
        crBuilder.setAccountTypes(IdentityProviders.GOOGLE, IdentityProviders.FACEBOOK);
    }

    ...
}

I'd love to send a pull request for this patch, but would like to first raise it here to see if there is a reasoning behind retrieving only the Google account type that I have overlooked in the grand scheme of things.

[samtstern]

@wuman a pull request is always welcome, thanks for the detailed issue report.
@amandle do you know why the code is currently this way?

[SUPERCILEX]

Fixed in #357.

[amandle]

@samtstern I don't know why it was written that way. It's strange since we have had Facebook support since the beginning. I will send a PR to fix this for this version of the code, and @SUPERCILEX's fix will land when #357 lands