GitLab

Clean up proprietary codec checks for EME. MP4 is not treated as
"proprietary" anymore. So "proprietary codec" should only be used for
real proprietary codes, e.g. AVC1 or AAC.

Bug: 327115,837783
Test: Tests updated.
Change-Id: I18b762ab543f2cf08c7dec195c28d3ee62143eb8
Reviewed-on: https://chromium-review.googlesource.com/1033695
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: John Rummell <jrummell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554623}