The NTP uses a service worker to fetch & cache resources from GWS. Once successfully installed, the updated worker will wait until the existing worker is controlling zero clients. (ie zero NTPs must be open before the update is available on any NTP).

We should understand & optimize SW usage, as it impacts several aspects of the NTP, including remote ntp resources, one google bar, and doodle.

Potential issues where this may have impact:
- 442344
- 521698
- 821078

https://developers.google.com/web/fundamentals/primers/service-workers/lifecycle