Avoid merging user cloud policies when merging multiple source policies

On desktop, the user cloud policy potentially comes from a different
domain/administrator than e.g. GPO policy or machine-level cloud policy,
 so prevent merging user cloud policy with other policy sources.
Note: In the future, merging may be allowed if an affiliation check
is possible and says that the user cloud policy and machine-level cloud
policy come from affiliated domains.

Bug: 950068
Change-Id: Id0d77671d682802f84054acf92ac74b7fd63ad64
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1572700
Commit-Queue: Yann Dago <ydago@chromium.org>
Reviewed-by: Pavol Marko <pmarko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653752}
2 files changed