Also worth noting <a href="https://lwn.net/Articles/1097760/" rel="nofollow">https://lwn.net/Articles/1097760/</a> - Gentoo has given up on building Chromium from source, because upstream "do not test their builds with any of their allegedly 'optional' features disabled" and "[i]n the case of Chromium, keeping all the toggle switches working (despite chronic neglect from upstream) is a monumental, nigh-insurmountable task." One maintainer said he could not possibly test all the combinations of USE flags in the Gentoo build, since his laptop took 15-16 hours to compile Chromium (I presume for just one build, which would have to be repeated 2^N times to test all possible flag combinations).<p>Much more in the LWN article, I'm not going to quote everything.