Fixed internal service state exposed to clients

This is another fix on top of aosp/1807858. Since service state
is not a immutable object, the instance notified to the client
should be a new copy, otherwise the exposed one can get modified
when SST internally modifies it.

Fix: 174306612
Test: Manual
Change-Id: I08311c01a841fee70f82a0a1809a8e13829447ce