GitLab

There was a mismatch between methods of retrieving GLX extensions in
Chrome, causing certain available/used extensions to not appear on
about::gpu. Additionally, there is an opportunity to cache the extension
string and save calls.

Bug: 1043761
Change-Id: I39bde9702daf9b5cf80a5cc1c9a030ef56623913
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2015644
Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735924}