Early on in the article you might see that you have to sign up for a token to use it while it's in the trial stage. If you're wondering what this is about, see https://github.com/GoogleChrome/OriginTrials/blob/gh-pages/d...

> The TL;DR is that we strongly value the feedback of real web developers (that means you!) during the process of designing and standardizing new features. We believe origin trials provide a good way of encouraging that feedback, while being extremely careful that the experiments aren’t used by sites in production-critical roles or as if they’re finalized features.