What was the design language used by Google prior to modern Material design?

You can still find it in very few places. Like Google Groups (see example). But even that, understandably, is getting a redesign, one that hides quite a bit of functionality and seems to dispose entirely of some (e.g. some filter options).

Screenshot:

I recall it was a "thing" with some PR work popularizing its launch across different Google products as a unification of their interface designs. I can't recall its name and no query gets me anything similar. And sadly there's no such thing as a compiled "history" of design languages used by a company even one as big as Google.