GitLab

- Implements the accept flow for a share request.
Todo - PayloadStatusTracker

Bug: 1085068
Change-Id: Ife793c110e39995d5484ae5edbd34103b64e69ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2332273
Commit-Queue: Himanshu Jaju <himanshujaju@chromium.org>
Reviewed-by: Alex Chau <alexchau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795857}