GitLab

This moves decoding of AV1 content via dav1d to a task pool instead of
sharing the media thread -- which was apparently leading to underflow
of the audio.

This probably only fixes pausing and audio drop outs, if a video frame
is taking more than 200ms (audio buffer size) to return, we've probably
exhausted the video frame buffer too. This would result in video
apprearing frozen for a moment, but would not trigger underflow since
we have a 3 second threshold for underflow on video.

Unlike the VP9 offloading, we offload for all resolutions of AV1
content, since we seem to be getting these issues even with 360p
content.

This removes an unnecessary BindToCurrentLoop for the OutputCB in
the non-offloaded case for clarity.

BUG=940686
TEST=all existing tests pass with offloading decoder.

Change-Id: I7426a0353249646600c12019f868aa058c40e456
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1574830
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Auto-Submit: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Chrome Cunningham <chcunningham@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652635}