Reason for revert:
Speculative revert to see if this CL caused a change in performance tests.
See https://bugs.chromium.org/p/chromium/issues/detail?id=689919 for details.
Original issue's description:
> Avoid calling PostTask in audio callbacks.
>
> We have seen that PostTask can consume some CPU and the way we used it
> before (logging only) in the ADB is not worth the cost we see when
> profiling.
>
> This CL simply moves frequent (trivial) stat updates from the task queue
> to the native threads to avoid calling PostTask in each callback.
> The reason for doing so before was to avoid locks but we can live without
> them since races are benign here.
>
>
> BUG=webrtc:7096
>
> Review-Url: https://codereview.webrtc.org/2663383004
> Cr-Commit-Position: refs/heads/master@{#16429}
> Committed: 77ce9a5541TBR=solenberg@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=webrtc:7096
Review-Url: https://codereview.webrtc.org/2684913003
Cr-Commit-Position: refs/heads/master@{#16490}
fd8f102a84