Keyed mutex support was deprecated and the only known client using it,
Chromium, has migrated to fences. Remove all related keyed mutex related
code and tests. The useFenceSynchronization field is still present in
the external image descriptor since it's set by Chromium (to true) -
it'll be removed once Chromium stops setting it.
Bug: dawn:1612
Change-Id: Iaec3c16b18bb8ddbde55a7f54eaf4b944d0f06c6
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/129300
Reviewed-by: Austin Eng <enga@chromium.org>
Auto-Submit: Sunny Sachanandani <sunnyps@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
c820dcc53e