Fix crash when dialog open attribute is removed manually
The recent [1] CL added a CHECK that when showing a dialog, there
is no existing close watcher, but it fails in the case that the
open attribute is manually removed. This CL fixes that case.
[1] https://chromium-review.googlesource.com/c/chromium/src/+/5990171
Fixed: 378159143
Bug: 376516550
Change-Id: I91e955d15bd109d176b7f2cf2b622431ca884909
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6013313
Commit-Queue: Mason Freed masonf@chromium.org
Auto-Submit: Mason Freed masonf@chromium.org
Reviewed-by: Joey Arhar jarhar@chromium.org
Commit-Queue: Joey Arhar jarhar@chromium.org
Cr-Commit-Position: refs/heads/main@{#1381372}