shill: vpn: Support Service.Name property change.

BUG=chromium:221577
TEST=Unit tests; Tested on device through configure-vpn; Also, tested
on device through corp policy and checked that the service got
renamed.

Change-Id: I936f85573e8d0820e2baa2361f94619e0e655f8f
Reviewed-on: https://gerrit.chromium.org/gerrit/46514
Reviewed-by: Darin Petkov <petkov@chromium.org>
Tested-by: Darin Petkov <petkov@chromium.org>
Commit-Queue: Darin Petkov <petkov@chromium.org>
diff --git a/vpn_service.h b/vpn_service.h
index 4fc46f2..4160690 100644
--- a/vpn_service.h
+++ b/vpn_service.h
@@ -34,6 +34,7 @@
   virtual bool Unload();
   virtual void MakeFavorite();
   virtual void SetConnection(const ConnectionRefPtr &connection);
+  virtual void SetNameProperty(const std::string &name, Error *error);
 
   virtual void InitDriverPropertyStore();