GitLab

These are loaded through WorkerShadowPage, and this CL to add a code to check
the preferences and add the header in there.

Bug: 853085
Change-Id: I080e3fa4cb175763b17dca127907750c51eef966
Reviewed-on: https://chromium-review.googlesource.com/1154782Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Makoto Shimazu <shimazu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579752}