GitLab

Holding space is enabled for guest sessions but previously redirected to
use original profile instead of OTR profile. This caused:

- Thumbnails to fail to render
- Opening Files app via util to fail

These failures are due to expectations further downstream that guest
sessions use OTR profiles.

To address this:
- Redirect to primary OTR profile in holding space for guest sessions
- Allow OTR profiles in FileChangeService for guest sessions

Note that FileChangeService was previously *not* created for OTR
profiles but they will now be allowed if the profile is a guest session.

This CL also modified FileChangeService to *not* create the service w/
the browser since the service does not need to exist until interacted
with.

Bug: 1165733, 1164329
Change-Id: I032aea25171594bdb0666c87564a80f7c0cfe203
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2625799
Commit-Queue: David Black <dmblack@google.com>
Reviewed-by: Toni Baržić <tbarzic@chromium.org>
Reviewed-by: Sergei Datsenko <dats@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842893}