unit_tests failing on chromium.chromiumos/Linux ChromiumOS Tests (dbg) (1)

Builders failed on: 
- Linux ChromiumOS Tests (dbg) (1): 
  https://uberchromegw.corp.google.com/i/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29?numbuilds=100

The flaki tests all seem to have the same error pattern in common, creating the device policy fails because FakeSessionManagerClient cannot create the directory. Sometimes, retries fix this.

I couldn't find any obvious cuplprit, so looping in the devs.

More example logs: https://chromium-swarm.appspot.com/task?id=397a4c8516e57110&refresh=10&show_raw=1


[ RUN      ] Cert/DeviceCloudPolicyManagerChromeOSEnrollmentTest.Reenrollment/1
[29139:29139:1027/224452.651759:23681551236:ERROR:fake_session_manager_client.cc(43)] Failed to create the directory for the owner key file
[29139:29139:1027/224452.651891:23681551361:ERROR:device_settings_service.cc(223)] Owner key change failed.
[29139:29363:1027/224452.652708:23681552180:ERROR:cloud_policy_validator.cc(357)] Policy signature validation failed
[29139:29139:1027/224452.652863:23681552333:ERROR:session_manager_operation.cc(215)] Policy validation failed: 2
[29139:29139:1027/224452.652938:23681552408:ERROR:device_settings_service.cc(316)] Session manager operation failed: 5
[29139:29139:1027/224452.653130:23681552601:ERROR:enrollment_handler_chromeos.cc(331)] Error in device policy store.
[29139:29139:1027/224452.653192:23681552661:WARNING:enrollment_handler_chromeos.cc(691)] Enrollment failed: 12, client: 0, validation: 0, store: 1, lock: 0
../../chrome/browser/chromeos/policy/device_cloud_policy_manager_chromeos_unittest.cc:466: Failure
      Expected: EnrollmentStatus::SUCCESS
      Which is: 0
To be equal to: status_.status()
      Which is: 12
../../chrome/browser/chromeos/policy/device_cloud_policy_manager_chromeos_unittest.cc:467: Failure
Value of: manager_->core()->client()
  Actual: false
Expected: true
[  FAILED  ] Cert/DeviceCloudPolicyManagerChromeOSEnrollmentTest.Reenrollment/1, where GetParam() = true (66 ms)