Calling setVisible multiple times in a row can cause a hang while
X11Window waits for events that will never be generted.

Change-Id: I43af8d4c79c7010dae78aa38c9716ed5b7b02865
Reviewed-on: https://chromium-review.googlesource.com/322380Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>