GitLab

Most of these merge scripts lived in tools/build. These are moving
source side so that:
* Devs can find it easily
* Tryjobs can test changes to it
* Different trigger scripts can share and re-use code

Bug: 928577
Change-Id: I6a78164a3b5dfe142983ec111756bd60f838b2a6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1479171Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Reviewed-by: Marc-Antoine Ruel <maruel@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Stephen Martinis <martiniss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638207}