Check if the display was valid (non-null Display pointer) before querying NVCTRL X11 extension. Bug: 840249 Change-Id: I299f87e2eb150d56649dd71c7becbe8f8abf7841 Reviewed-on: https://chromium-review.googlesource.com/c/1392906Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>
