Revert "Revert "enable libaom""

This reverts commit f7eb8650bbec6ecd051caf89e3bb144e075578e6.

The msan build failure has been addressed:
https://chromium-review.googlesource.com/c/chromium/src/+/806634

Original change's description:
> Reason for revert: Broke linux msan builder:
> https://ci.chromium.org/buildbot/chromium.memory/Linux%20MSan%20Builder/7457

BUG=783519

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_msan_rel_ng

R=tomfinegan@chromium.org,dalecurtis@chromium.org

Change-Id: I720447e099700e1bce0868590d31943beb370643
Reviewed-on: https://chromium-review.googlesource.com/806875
Reviewed-by: Tom Finegan <tomfinegan@chromium.org>
Commit-Queue: Johann Koenig <johannkoenig@google.com>
Cr-Commit-Position: refs/heads/master@{#521477}
1 file changed