code: function(provider) {
        if (!this.isCurrent()) {
          return;
        }
        var authType;
        if (_.isString(provider)) {
          authType = provider;
          provider = Parse.User._authProviders[authType];
        } else {
          authType = provider.getAuthType();
        }
        var authData = this.get('authData');
        if (!authData || !provider) {
          return;
        }
        var success = provider.restoreAuthentication(authData[authType]);
        if (!success) {
          this._unlinkFrom(provider);
        }
      }
docs: Synchronizes auth data for a provider (e.g. puts the access token in the
  right place to be used by the Facebook SDK).