constructor(
      onEmailEnter, tosCallback = undefined, privacyPolicyCallback = undefined,
      domHelper = undefined) {
    super(
        page.providerMatchByEmail,
        undefined, domHelper, 'providerMatchByEmail', {
          tosCallback: tosCallback,
          privacyPolicyCallback: privacyPolicyCallback,
        });
    this.onEmailEnter_ = onEmailEnter;
  }
@param {function()} onEmailEnter Callback to invoke when enter key
    (or its equivalent) is detected.
@param {?function()=} tosCallback The optional callback to invoke when the
    ToS link is clicked.
@param {?function()=} privacyPolicyCallback The optional callback to
    invoke when the Privacy Policy link is clicked.
@param {?DomHelper=} domHelper Optional DOM helper.