GitLab

This lands patch set 16 of https://codereview.chromium.org/1551753002/
(reviewed there), except for the changes to build/common.gypi and
build/config/compiler/BUILD.gn.  The changes to these two files are likely
to break some bot I don't know about, and I don't want to keep reverting
and relanding all these files.  So this lands the parts that are hopefully
harmless separately.

BUG=573250
TBR=thestig

Review URL: https://codereview.chromium.org/1557733002

Cr-Commit-Position: refs/heads/master@{#367252}