GitLab

This adds a new (internal) mojo interface that will be used by IndexedDB
code (in the Storage Service process) to talk to Native File System code
(in the browser process) to serialize and deserialize handles.

Bug: 955193
Tbr: pwnall@chromium.org
Change-Id: I01aad3db0787483caff11f94904eda00829c6033
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2025950
Commit-Queue: Marijn Kruisselbrink <mek@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Joshua Bell <jsbell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#737517}