GitLab

Original patch https://crrev.com/c/1599620

MultiThreadedPromiseTest.CrossThreadThens had a race between the
resolve on thread b and thread a posting a bunch of tasks including
the quit closure which would sometimes arrive mid way through
thread b posting eligible thens.



Implements Then and Catch on top of AbstractPromise as well as
ManualPromiseResolver<> which is needed for testing at this
stage (PostTask doesn't yet return a promise). It's also
necessary for promises to interface with old style callback
based libraries which are extremely common in Chromium.

Design: https://docs.google.com/document/d/1l12PAJgEtlrqTXKiw6mk2cR2jP7FAfCCDr-DGIdiC9w/edit

TBR=fdoray@chromium.org, etiennep@chromium.org

Bug: 906125
Change-Id: I95bbd0f1a709643cd4a813e378b625a91f2abe7a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1617769Reviewed-by: Alex Clarke <alexclarke@chromium.org>
Commit-Queue: Alex Clarke <alexclarke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661171}