I think that breaks VM images, platform_FilePerms failed last night:
https://luci-milo.appspot.com/buildbot/chromeos/betty-release/333

See the test log https://pantheon.corp.google.com/storage/browser/chromeos-image-archive/betty-release/R61-9734.0.0/vm_test_results_1/smoke_suite/test_harness/all/SimpleTestVerify/1_autotest_tests/results-32-platform_FilePerms/debug/ 

07/11 07:50:18.186 ERROR|platform_FilePerms:0423| No expectations entry for "/run/arc/debugfs/sync" with info "{'device': 'debugfs', 'type': 'debugfs', 'options': ['rw', 'seclabel', 'nosuid', 'nodev', 'noexec', 'relatime', 'gid=605', 'mode=750']}"
07/11 07:50:18.191 ERROR|platform_FilePerms:0430| [/etc/mtab] "/run/arc/debugfs/tracing" has type "tracefs", expected type "debugfs"
07/11 07:50:18.195 ERROR|platform_FilePerms:0450| [/etc/mtab] "/run/arc/debugfs/tracing" is missing options "set(['gid=605', 'mode=750'])"

Likely https://chromium-review.googlesource.com/c/562939/ ?

Breaking PreCQ so P0.