GitLab

Adds retry functionality with
* random guid on every URL
* linear and exponential backoff

Bug: 977603
Change-Id: I02ba45ea578e75a1a750b8f42d77959edb1fe187
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1677369Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Robert Ogden <robertogden@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672608}