Chrome needs ANGLE to pass through the underlying driver vendor and
version, which cannot always be determined by the SystemInfo library.
This is done by construction GL_RENDERER in the frontend through
combining GL_VENDOR, GL_RENDERER, and GL_VERSION from the backends.

Example changes are in the doc:
https://docs.google.com/document/d/1p0dvrLlu8NKhO-RCU5gqlQ_LvcQj-ZqhvfwSk1n3Sz8/edit?usp=sharing

Bug: chromium:1126526
Bug: chromium:1131248
Bug: chromium:1134669
Bug: chromium:1169861
Change-Id: Ia618ebcd7f3caaeb376b4b6a03446732efdaeecb
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2427383
Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>