[reland] x11: Don't wait on a MapNotify on override-redirect windows.

[This reland should theoretically fix a case where timing issues on
AMD drivers appear to cause a blank window by forcing a redraw when
we are an override-redirect window and receive a MapNotify.]

Some window managers do not send MapNotify on override-redirect
windows. Enlightenment doesn't send one, XFCE does, and I don't know
which behaviour is more common.

This makes mapping resilient against whether we would have received a
MapNotify message on override-redirect window. On override-redirect
windows, we immediately trigger the code that would run in the future
MapNotify handler, and ignore it in the future MapNotify message if it
is already run.

BUG=381732,606661
First Review URL: https://codereview.chromium.org/1896363004

Review-Url: https://codereview.chromium.org/1933923002
Cr-Commit-Position: refs/heads/master@{#390773}
2 files changed