I would characterize the amount of Rust being done at Google as ... insignifant.
That could change, but apart from Fuchsia and maybe some kernel driver work I struggle to picture where it would fit in the language pantheon there.
I am in contact with some people in the Android team at Google that are also using Rust (and that want to use Miri :D ).
But I'm sure it's growing. But it won't be in the core Google3-on-Borg parts of Google, which are on the whole in either C++ or (increasingly) Go. Switching to a standardized garbage collected Google supported language makes sense in that domain. The "Carbon" stuff recently announced sounds interesting as well.
The long term looks good for Rust. But actual production code is still thin on the ground still everywhere.
FWIW, to the best of my memory as of a year ago I counted ~1.1 MLoC of Rust code in our open source tree, with an additional ~1.3 MLoC in things we've vendored from crates.io.
There was a bit more C++ when I did the analysis, but it was the same order of magnitude.
Other than that... Fuchsia was the thing that was rewriting all my work from scratch and killing everything I worked on (Chromecast on Home Hub, etc), so... :-)