GitLab

https://github.com/WICG/encrypted-media-encryption-scheme/blob/master/explainer.md
has been updated to state "If encryptionScheme from the application is null
or missing, the encryptionScheme fields in the returned configuration must
be null." So updating Chrome to match this.

BUG=852978
TEST=updated LayoutTest passes

Change-Id: I7c5c39b93018fdc8208df5f25c0ef6c4f60e83f5
Reviewed-on: https://chromium-review.googlesource.com/1102000Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Commit-Queue: John Rummell <jrummell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567818}