GitLab

Implements the new bindings generator of IDL callback functions
and IDL callback interfaces.

Bug: 839389
Change-Id: I49af9220f63ff86f1d166408cfb79c6531d71f37
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2434004Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811158}