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These apps exist on system image and available for all users. This also
moves custom Play Store case handled separately before to system app.

TEST=unit test
BUG=1013730

Change-Id: Iaf63d52c38c376b6b07930bc8ec88e5b9de4bb58
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1865472Reviewed-by: Josh Horwich <jhorwich@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Yury Khmel <khmel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706920}