Revert "Disable managed UI for Unicorn accounts"

This reverts commit 27bdec41e1a04f12f59744b8450b63facbed98ae.

Reason for revert: This patch is suspicious to have caused failure at ManagedUIHandlerTest in unit_tests.

https://findit-for-me.appspot.com/waterfall/failure?url=https://build.chromium.org/p/chromium.memory/builders/Linux%20CFI/builds/12632

Original change's description:
> Disable managed UI for Unicorn accounts
> 
> Bug: 924836
> Change-Id: Ib03b926e770adcfe8678ee64ec2094c117724314
> Reviewed-on: https://chromium-review.googlesource.com/c/1436141
> Commit-Queue: Nicolas Ouellet-Payeur <nicolaso@chromium.org>
> Reviewed-by: Michael Wasserman <msw@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#628790}

TBR=msw@chromium.org,michaelpg@chromium.org,menegola@chromium.org,nicolaso@chromium.org

Change-Id: I1cadade31b09cbc6290b41686811f9630ec24c7f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 924836
Reviewed-on: https://chromium-review.googlesource.com/c/1454343
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629064}
4 files changed