debugd calls "tpm-manager get_version_info" to report tpm_version. verified that when run from root, this command reports correct version info:
localhost ~ # tpm-manager get_version_info
tpm_family 312e3200
spec_level 0000000200000003
vendor 49465800
tpm_model ffffffff
firmware_version 0000000000000628
vendor_specific 062800be0074706d733135ffff
version_fingerprint 987973414 3ae34726

But when run as chronos, this error is seen:
localhost ~ # su chronos
chronos@localhost /root $ tpm-manager get_version_info
[ERROR:tpm_impl.cc(495)] TPM error 0x3011 (Communication failure): Error calling Tspi_Context_Connect
[ERROR:tpm_impl.cc(495)] TPM error 0x3011 (Communication failure): Error calling Tspi_Context_Connect
[ERROR:tpm_impl.cc(3024)] Could not open the TPM

This error is not seen on R68-10718.48.0. The tpm version is reported correctly there.

And this may be the reason: https://crrev.com/c/1053426 ?

Confirmed that new minijail restrictions in CL:1053426 were the reason. Submitted crrev.com/c/1134417 for review.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/32d7c9a3b2b8ce29383e535bf18c173651e9a78a

commit 32d7c9a3b2b8ce29383e535bf18c173651e9a78a
Author: Andrey Pronin <apronin@chromium.org>
Date: Sun Jul 15 01:11:48 2018

debugd: add tpm to IUSE

To allow conditional mounting of tcsd socket directory in CL:1134417
add tpm flag to IUSE for debugd.

BUG= chromium:862429 
TEST=build

Change-Id: I58fc8873514c1413f87a956fa55f0280978eb13a
Reviewed-on: https://chromium-review.googlesource.com/1136859
Commit-Ready: Andrey Pronin <apronin@chromium.org>
Tested-by: Andrey Pronin <apronin@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[modify] https://crrev.com/32d7c9a3b2b8ce29383e535bf18c173651e9a78a/chromeos-base/debugd/debugd-9999.ebuild

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/trousers/+/5501789276d0afb9eff8bbd35db8beaf743fe4af

commit 5501789276d0afb9eff8bbd35db8beaf743fe4af
Author: Andrey Pronin <apronin@chromium.org>
Date: Sun Jul 15 01:11:39 2018

trousers: move tcsd.socket to /run/tcsd

Move tcsd.socket to a dedicated directory in /run to allow minijailed
daemons that need it mount that directory instead of the socket
directly. This avoids race conditions in cases when those daemons
are started in parallel with tcsd.

BUG= chromium:862429 
TEST=boot, login-logout successfully on a device with TPM 1.2

Change-Id: I8982206a9c1fa96875a829de2df0b19f82582da3
Reviewed-on: https://chromium-review.googlesource.com/1136845
Commit-Ready: Andrey Pronin <apronin@chromium.org>
Tested-by: Andrey Pronin <apronin@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[modify] https://crrev.com/5501789276d0afb9eff8bbd35db8beaf743fe4af/src/include/tcsd.h
[modify] https://crrev.com/5501789276d0afb9eff8bbd35db8beaf743fe4af/init/tpm-probe.conf

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/0f029d8ea85fef93b0bc0c3cde1267f11128b55b

commit 0f029d8ea85fef93b0bc0c3cde1267f11128b55b
Author: Andrey Pronin <apronin@chromium.org>
Date: Sun Jul 15 01:11:42 2018

debugd: allow access to tcsd socket from minijail

On devices with TPM1.2, debugd runs utilities that need to access
TPM via tcsd.
This CL allows access to tcsd socket from inside debug minijail.

BUG= chromium:862429 
TEST=1) check that 'tpm_version' in chrome://system shows version info
     and not access errors on device with TPM 1.2;
     2) check that debugd starts on devices with TPM 1.2 and 2.0.

Change-Id: I679b89793320b6f7c915f8f702d76ea7eec37182
Reviewed-on: https://chromium-review.googlesource.com/1134417
Commit-Ready: Andrey Pronin <apronin@chromium.org>
Tested-by: Andrey Pronin <apronin@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[modify] https://crrev.com/0f029d8ea85fef93b0bc0c3cde1267f11128b55b/debugd/debugd.gyp
[modify] https://crrev.com/0f029d8ea85fef93b0bc0c3cde1267f11128b55b/debugd/src/main.cc
[modify] https://crrev.com/0f029d8ea85fef93b0bc0c3cde1267f11128b55b/common-mk/common.gypi