Reinitialize GL_VENDOR string when GPU switches
Reinitialize GL_VENDOR string when GPU switches

We already update the GL_RENDERER string. We should do the same for
GL_VENDOR so this information is passed along correctly.

Bug: chromium:1152212
Change-Id: I639700bfebdc9e77ec3c6b41fcd6516e8c32139d
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2560824
Reviewed-by: Jonah Ryan-Davis <682bdb9e7d8ba359ef169b8db374e7a99d394a46@google.com>
Reviewed-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>
Commit-Queue: Jonah Ryan-Davis <682bdb9e7d8ba359ef169b8db374e7a99d394a46@google.com>

ppy/angle,ppy/angle,ppy/angle,ppy/angle