code: public void finish() {
          if (mAccountAuthenticatorResponse != null) {
              // send the result bundle back if set, otherwise send an error.
              if (mResultBundle != null) {
                  mAccountAuthenticatorResponse.onResult(mResultBundle);
              } else {
                  mAccountAuthenticatorResponse.onError(AccountManager.ERROR_CODE_CANCELED,
                          "canceled");
              }
              mAccountAuthenticatorResponse = null;
          }
          super.finish();
      }
docs: Sends the result or a Constants.ERROR_CODE_CANCELED error if a result isn't present.