GitLab

Changes the expected schema format that indicates promise support to no
longer specify a callback in the parameters, but instead supply a
"returns_async" key. This key species the format of the return value to
the promise, or to the callback if one is supplied. Also adjusts
associated tests to check for such.

Bug: 978538
Change-Id: Ifcb0b8e8152fd6b6c9049e2d856b10d577c955fa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2253205Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Tim Judkins <tjudkins@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782031}