code: function(provider) {
          if (!this.isCurrent()) {
            return;
          }
          var authType;
          if (_.isString(provider)) {
            authType = provider;
            provider = AV.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.dissociateAuthData(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).
  @private