GitLab

Follow-up CLs will add this to the graph display, and then
individually wire up the types of opener relationships.

BUG=1085129

Change-Id: If25406e0bc15fd6c6cbeeb62cc0db0c438fe9ea3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2215281
Commit-Queue: Chris Hamilton <chrisha@chromium.org>
Reviewed-by: Sigurður Ásgeirsson <siggi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#772265}