[Sync::USS] Commit local bookmark updates

This CL process local updates in the bookmarks model and updates the
tracker accordingly.

Bug: 516866
Change-Id: Idfa2f2e7822029fb71030e3decbc6d8091856737
Reviewed-on: https://chromium-review.googlesource.com/1124164
Commit-Queue: Mohamed Amir Yosef <[email protected]>
Reviewed-by: Mikel Astiz <[email protected]>
Cr-Commit-Position: refs/heads/master@{#572230}
3 files changed