Add keystore API for metrics re-routing.

Keystore2 atoms need to be routed to statsd via a proxy.
The proxy needs to call this API in order to pull metrics from
keystore.

Bug: 188590587
Test: Statsd Testdrive script
Merged-In: I28f8675fe5467b0760418c4d2d87808e45657be1

Change-Id: I28f8675fe5467b0760418c4d2d87808e45657be1
diff --git a/keystore2/src/lib.rs b/keystore2/src/lib.rs
index 51316d7..8b629b1 100644
--- a/keystore2/src/lib.rs
+++ b/keystore2/src/lib.rs
@@ -32,6 +32,7 @@
 pub mod legacy_migrator;
 pub mod maintenance;
 pub mod metrics;
+pub mod metrics_store;
 pub mod operation;
 pub mod permission;
 pub mod raw_device;