Short term fix is in place. I just blew away that .cache directory.

However, we have a file permissions problem that needs a more permanent fix.

Did you happen to check exactly which file in the path was root owned?

See https://chromium-review.googlesource.com/#/c/401998/ for a recent fix to an almost same problem. I want to know that that fix actually worked.

Also, the offending checkout path was recently changed: https://chromium-review.googlesource.com/#/c/403369/

The directory with the problem is the one listed in comment 0.

My fix is to improve our ChromeSync clobber code to cleanup as root. But that doesn't explain how the directories ended up root owned.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/ad54ff297b1ab7e9932a8e625f1278f0c0b12565

commit ad54ff297b1ab7e9932a8e625f1278f0c0b12565
Author: Don Garrett <dgarrett@google.com>
Date: Fri Nov 04 19:38:13 2016

sync_chrome: Use root to clobber a bad checkout.

We clobber and retry the Chrome sync after an error to recover from
corruption. However, the clobber needs root to clean up files with the
wrong owner (which has somehow happened).

BUG= chromium:662211 
TEST=None

Change-Id: Iac3e3c5366faf028f74702de70b8a5d1264fbd17
Reviewed-on: https://chromium-review.googlesource.com/407960
Commit-Ready: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[modify] https://crrev.com/ad54ff297b1ab7e9932a8e625f1278f0c0b12565/scripts/sync_chrome.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/a1486759cfc83e03f54765566d8eea6dfa1622fa

commit a1486759cfc83e03f54765566d8eea6dfa1622fa
Author: Don Garrett <dgarrett@google.com>
Date: Fri Nov 04 19:38:13 2016

sync_chrome: Use root to clobber a bad checkout.

We clobber and retry the Chrome sync after an error to recover from
corruption. However, the clobber needs root to clean up files with the
wrong owner (which has somehow happened).

BUG= chromium:662211 
TEST=None

Change-Id: Iac3e3c5366faf028f74702de70b8a5d1264fbd17
Reviewed-on: https://chromium-review.googlesource.com/407960
Commit-Ready: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
(cherry picked from commit ad54ff297b1ab7e9932a8e625f1278f0c0b12565)
Reviewed-on: https://chromium-review.googlesource.com/419781
Tested-by: YH Lin <yueherngl@chromium.org>
Reviewed-by: YH Lin <yueherngl@chromium.org>
Commit-Queue: YH Lin <yueherngl@chromium.org>

[modify] https://crrev.com/a1486759cfc83e03f54765566d8eea6dfa1622fa/scripts/sync_chrome.py