Change ownership of AuthManager as it's needed by DeviceRegistrationInfo

BUG=25766813

Change-Id: I832e0ee9e440ecc4a754dd6d4dacd3c171fbab21
Reviewed-on: https://weave-review.googlesource.com/1825
Reviewed-by: Alex Vakulenko <avakulenko@google.com>
diff --git a/src/privet/security_manager.h b/src/privet/security_manager.h
index 26a42d4..cab042a 100644
--- a/src/privet/security_manager.h
+++ b/src/privet/security_manager.h
@@ -84,6 +84,8 @@
   void RegisterPairingListeners(const PairingStartListener& on_start,
                                 const PairingEndListener& on_end);
 
+  const AuthManager* GetAuthManager() const { return auth_manager_; }
+
  private:
   FRIEND_TEST_ALL_PREFIXES(SecurityManagerTest, ThrottlePairing);
   // Allows limited number of new sessions without successful authorization.