This directory exists solely to hold shims for compatibility with the Chromium reposository of Khronos headers. That repo is significantly easier to use than the upstream verions, since:

• The upstream headers are spread over two repositories.
• The upstream repositories are large, due to files that aren't relevant for building (see https://github.com/KhronosGroup/OpenGL-Registry#there-sure-is-a-lot-of-stuff-in-here).
• The Chromium version already has a BUILD.gn file.

However, it contains slight forking to add Chromium-specific headers, so this folder provides dummy versions of those headers.