As of late May Google Fonts has added support for a display querystring parameter. Using it you can control the CSS font-display Property which allows you to control what happens while the font is unavailable.
Specifying https://fonts.googleapis.com/css?family=Roboto&display=swap as the font to load, will yield the following:
@font-face {
font-family: 'Roboto';
font-style: normal;
font-weight: 400;
font-display: swap;
src: local('Roboto'), local('Roboto-Regular'), url(https://fonts.gstatic.com/s/roboto/v19/KFOmCnqEu92Fr1Mu4mxKKTU1Kg.woff2) format('woff2');
}