shill: tighten up constness of PropertyStore

BUG=chromium-os:20543
TEST=unittest

Change-Id: Ifa86f82a883b3c3ec61ce10f8d82564b9a036b04
Reviewed-on: http://gerrit.chromium.org/gerrit/7901
Tested-by: mukesh agrawal <quiche@chromium.org>
Reviewed-by: Chris Masone <cmasone@chromium.org>
diff --git a/mock_manager.h b/mock_manager.h
index bc3280e..164afa3 100644
--- a/mock_manager.h
+++ b/mock_manager.h
@@ -20,7 +20,8 @@
   virtual ~MockManager();
 
   MOCK_METHOD0(device_info, DeviceInfo*(void));
-  MOCK_METHOD0(store, PropertyStore*(void));
+  MOCK_METHOD0(mutable_store, PropertyStore*(void));
+  MOCK_CONST_METHOD0(store, const PropertyStore&(void));
   MOCK_METHOD1(RegisterService, void(const ServiceRefPtr &to_manage));
   MOCK_METHOD1(UpdateService, void(const ServiceConstRefPtr &to_update));