We will be running an Origin Trial to allow retrieving legacy counters from performance.memory for some time.

Explainer: https://docs.google.com/document/d/1eGvXIWNRdmFF6FA1I2tpBTTJk08tZ6RNoVlPZx6DaH0

Intent to experiment: https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/RUSjTZ-qdmg/discussion

If you're signed up to that Origin Trial, please leave your feedback here.