https://google.github.io/styleguide/pyguide.html#34-indentat... suggests that they use four spaces.
> New projects should use that unmodified public Python Google style guide (4 space indent with methods_with_underscores). Historically, we adopted a style that was congruent with Google internal Python style guide (2 spaces with MethodsAsCamelCase).
https://chromium.googlesource.com/chromiumos/docs/+/HEAD/sty...