We're based on the ChromeOS SDKs... which use emerge to build the binaries required to assemble the distro. You can think of emerge/gentoo as the toolchain used

We're based on the ChromeOS SDKs... which use emerge to build the binaries required to assemble the distro. You can think of emerge/gentoo as the toolchain used to build all the binaries. We also pull base system packages from upstream portage, then compile them all together in out image.