GitLab

API and motivations described here:
https://github.com/WICG/web-codecs/issues/98

Spec PR here:
https://github.com/WICG/web-codecs/pull/120

Bug: 1141707
Test: new layout tests
Change-Id: I3a0f3cbc2bb64a86dcefdc454d6b03e72d3f36bd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2622421Reviewed-by: Thomas Guilbert <tguilbert@chromium.org>
Commit-Queue: Chrome Cunningham <chcunningham@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842153}