Could it be Selinux issues (See b/31596847)

Yeah, I've managed to make it run in normal login (b/34265977),
but there may be some difference in the autotest case.

I'll first try with permissive mode.

Update: SELINUX=permissive didn't help.

https://cs.chromium.org/chromium/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome/cros_browser_backend.py?q=RestartUI+file:%5Esrc/third_party/catapult/telemetry/&sq=package:chromium&dr=C&l=262

  def _WaitForLogin(self):
    # Wait for cryptohome to mount.
    py_utils.WaitFor(self._IsLoggedIn, 900)

Found a fishy line

https://cs.chromium.org/chromium/src/third_party/catapult/telemetry/telemetry/core/cros_interface.py?q=IsCryptohomeMounted+file:%5Esrc/third_party/catapult/telemetry/&sq=package:chromium&l=489&dr=CSs

hmm

By changing the wait condition to something like

os.path.exists(os.path.join(profile_path, 'Downloads'))

fixed the issue (cheets_CTSHelper succeeded). So, all I need to do is to come up with the most appropriate condition.

Btw, I now tried running CTS on top of it

$ test_that -b $BOARD $REMOTE cheets_CTS.6.0_r14.x86.android.text

It failed but the failure was common to N, not ext4crypto specific. See b/34693932.

CL: https://codereview.chromium.org/2651343002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5cfea4683bf32b75191cc16bb47942cee1f142d0

commit 5cfea4683bf32b75191cc16bb47942cee1f142d0
Author: catapult-deps-roller <catapult-deps-roller@chromium.org>
Date: Tue Feb 07 01:25:30 2017

Roll src/third_party/catapult/ 05e3d606d..a448b4b83 (2 commits).

https://chromium.googlesource.com/external/github.com/catapult-project/catapult.git/+log/05e3d606dd50..a448b4b8357a

$ git log 05e3d606d..a448b4b83 --date=short --no-merges --format='%ad %ae %s'
2017-02-06 kinaba CrOS: Make IsCryptohomeMounted compatible with ext4-encryption backend.
2017-02-06 benjhayden Assign a static NAME to DeviceInfo diagnostics.

BUG= 684914 

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, see:
http://www.chromium.org/developers/tree-sheriffs/sheriff-details-chromium#TOC-Failures-due-to-DEPS-rolls

CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.android:android_optional_gpu_tests_rel
TBR=catapult-sheriff@chromium.org

Review-Url: https://codereview.chromium.org/2677233004
Cr-Commit-Position: refs/heads/master@{#448494}

[modify] https://crrev.com/5cfea4683bf32b75191cc16bb47942cee1f142d0/DEPS

It's landed to Catapult and Catapult roll to Chrome has happened.
The last thing we need to wait is Chrome roll to Chrome OS.

Chrome roll of 58.0.3005 happened
https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/4fe11d25eaf1d05eb49b1c360950e0fa20149783
which includes the catapult roll. Closing.