GitLab

Make controls appear on preview area when custom margins is selected.
Controls do not yet work.

Bug: 773928, 812095
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ia0319b743736717f94af65c3ef364b65f2193571
Reviewed-on: https://chromium-review.googlesource.com/935681
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542918}