While supporting and improving popular open source framework Angular framework,
Google is internally using an alternative, not open, framework called "Wiz"
"Wiz runs most of Google's consumer web apps."
Wiz is used in combination with AMP (Accelerated Mobile Pages) web components.
Default internal protocol for Google tools is Protocol Buffers, not popular JSON/REST.
Not to mention that while externally Google is pushing Kubernetes, internally is still using Borg.
This is an informative interview with Tech lead of the AMP Project:
How Google builds web frameworks – freeCodeCamp.org