[Task APIs] Stop the bleeding while design discussions are in-progress

We had landed the previously agreed upon API but recent design
discussions have invalidated previous decisions. To stop the bleeding
let's at least revert the documentation until we have a fully
approved plan.

[email protected], [email protected]

Bug: 1026641
Change-Id: Idf0c2deafbd7fcd85541272f04fcd93cc745ce73
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1926533
Commit-Queue: Gabriel Charette <[email protected]>
Reviewed-by: Darin Fisher <[email protected]>
Reviewed-by: Alexander Timin <[email protected]>
Cr-Commit-Position: refs/heads/master@{#717214}
5 files changed