GitLab

- Integrates PayloadTracker in NearbySharingService.
- Registers PayloadPaths for incoming connections.
- Handles transfer completion and cleanup for incoming connections.

Bug: 1085068
Change-Id: Ic8df7bab0077c3fd3c95042831dcff7b07faf29b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2367677
Commit-Queue: Himanshu Jaju <himanshujaju@chromium.org>
Reviewed-by: Alex Chau <alexchau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#802610}