A former co-worker of mine is now at Google and wants to contribute ebuilds he wrote for ChromeOS to Gentoo. They add packages necessary for Vulkan (new 3D graphics API).
For instance: https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/master/media-libs/vulkan-loader/vulkan-loader-1.0.24.0.ebuild The copyright header says "Copyright 2016 The Chromium OS Authors. All rights reserved." All ebuilds in gentoo.git say "Copyright 1999-20xx Gentoo Foundation". Can I add ebuilds copyrighted by others to gentoo.git?