I have compiled ChromiumOS from sources. But I can't find how to enable additional codecs. There are only hacks on the internet which copy libraries from Chrome. There is a page https:// chromium.org/audio-video which describes how to enable codecs, but I can't understand where in ChromiumOS sources I can do that.
Also I can't import certificates. All buttons in Certificates settings are disabled. Why? And Google Drive doesn't work with Files application.

Are there any solutions for these issues?