Collect driver vendor in linux through glXGetClientString.
Collect driver vendor in linux through glXGetClientString.

This helps in the situation where libpci is unavailable: at least we can identify a few vendors.

Unfortunately we can not run this in preliminary GPU info collection because gl binding hasn't been initialized yet.

BUG=78526
TEST=bots green
Review URL: http://codereview.chromium.org/6803024

git-svn-id: http://src.chromium.org/svn/trunk/src@80876 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 184d0a15cdc45b6e6f8bb90c4a8fbd3d0687abef
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser