trunks: Add the trunks user and group

This CL creates the trunks user and groups.
It also adds trunks to the TSS group, so that it
can talk to the TPM.

BUG=chromium:372012
TEST=Ran build_packages, build_image and cros flash to a new DUT
     then checked if trunks user and groups were present in the DUT
CQ-DEPEND=CL:214228

Change-Id: I4c5d1bbb4a60caa2282003f47ea7755bf3128f5c
Reviewed-on: https://chromium-review.googlesource.com/214025
Reviewed-by: Utkarsh Sanghi <usanghi@chromium.org>
Commit-Queue: Utkarsh Sanghi <usanghi@chromium.org>
Tested-by: Utkarsh Sanghi <usanghi@chromium.org>
diff --git a/profiles/base/accounts/group/trunks b/profiles/base/accounts/group/trunks
new file mode 100644
index 0000000..9cfc3af
--- /dev/null
+++ b/profiles/base/accounts/group/trunks
@@ -0,0 +1,3 @@
+group:trunks
+gid:251
+users:trunks
diff --git a/profiles/base/accounts/group/tss b/profiles/base/accounts/group/tss
index 799a18e..f345727 100644
--- a/profiles/base/accounts/group/tss
+++ b/profiles/base/accounts/group/tss
@@ -1,4 +1,4 @@
 group:tss
 gid:207
-# Only root, chaps, and attestation are allowed to talk to the TPM via tcsd.
-users:root,chaps,attestation
+# Only certain users are allowed to talk to the TPM via tcsd.
+users:root,chaps,attestation,trunks
diff --git a/profiles/base/accounts/user/trunks b/profiles/base/accounts/user/trunks
new file mode 100644
index 0000000..12c533d
--- /dev/null
+++ b/profiles/base/accounts/user/trunks
@@ -0,0 +1,6 @@
+user:trunks
+uid:251
+gid:251
+gecos:Chromium OS trunks daemon runs as this user
+home:/dev/null
+shell:/bin/false