GN is a meta-build system that generates build files for Ninja.
https://gn-review.googlesource.com/c/gn/+/10980/2 (merged)
This project provides a header file that can be included into your application whenever you need to make direct system calls.
https://chromium-review.googlesource.com/c/linux-syscall-support/+/2652675 (merged)
A set of client and server components which implement a crash-reporting system.
Abseil is an open-source collection of C++ code (compliant to C++11) designed to augment the C++ standard library.
abseil/abseil-cpp#889 (merged)
gperftools is a collection of a high-performance multi-threaded malloc() implementation, plus some pretty nifty performance analysis tools.
gperftools/gperftools#1243 (merged)
BoringSSL is a fork of OpenSSL that is designed to meet Google's needs.
https://boringssl-review.googlesource.com/c/boringssl/+/45364 (not going to be merged :( )
The LLVM Project is a collection of modular and reusable compiler and toolchain technologies.
https://reviews.llvm.org/D95940 (compilation, no backend!)
A library to benchmark code snippets, similar to unit tests.
google/benchmark#1091 (merged)