This is used to address a CTS testcase failure. This CTS
testcase need to access the content of Contact, some data
from ContactProvider is transfered through ashmem.

Currently ashmem is backed by the tmpfs filesystem, ContactProvider
in android run as a priv_app, so the file context of the ashmem
created by ContactProvider is priv_app_tmpfs. CTS runs as an
untrusted_app, need to be granted the read permission to the
priv_app_tmpfs files.

Bug: 117961216

[Android Version]:
android_p_mr0_r0

[Kernel Version]:
4.19.0-rc8

[CTS Version]:
cts-9.0_r1

[Failed Testcase]:
com.android.cts.devicepolicy.ManagedProfileTest#testManagedContactsPolicies

[Error Log]:
11-11 11:15:50.479 12611 12611 W AndroidTestSuit: type=1400 audit(0.0:811):
avc: denied { read } for path=2F6465762F6173686D656D202864656C6574656429
dev="tmpfs" ino=174636 scontext=u:r:untrusted_app:s0:c113,c256,c522,c768
tcontext=u:object_r:priv_app_tmpfs:s0:c522,c768 tclass=file permissive=0

[Test Result With This Patch]:
PASS

Change-Id: I45efacabe64af36912a53df60ac059889fde1629