testSend_includeCredentials() {
    factory.setCredentialsMode(/** @type {RequestCredentials} */ ('include'));
    fetchMock(new Request('https://www.google.com', {
      headers: new Headers(),
      method: 'POST',
      credentials: 'include',
    })).$returns(Promise.resolve(createSuccessResponse()));

    mockControl.$replayAll();
    return verifySend('POST');
  }
Verifies the send method including credentials.
@return {!Promise<void>}