GitLab

Duplicate, Map, and MapAt on these various types do not and should not
need to modify the calling object.

Bug: 826213
Change-Id: Ice07621c23f36da00e20a13076a783cf1e41d7f2
Reviewed-on: https://chromium-review.googlesource.com/990673Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Ken Rockot <rockot@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547539}