The Chrome DevTools team gave this presentation at Google I/O 2016.
The code for the exact demo app used in their presentation apparently isn't public, but was based on the progressive web app CodeLabs demo, the code for which is here, in the 'final' directory.
Progressive web apps have a responsive design and define a manifest.json, which gives URLs for launcher icons and the start URL for the app. With the manifest.json in place, users can add the web app to their device home screen and launch it directly. Another common feature of progressive web apps is their use of service workers to cache resources, which allows them to load quickly, cut down on network use, and potentially work offline.