Add module for counting date-last-roll-call and persisting those counts

components/update_client/update_engine.h

Index: components/update_client/update_engine.h
diff --git a/components/update_client/update_engine.h b/components/update_client/update_engine.h
index 1d69ece4d62ca51363623fb2b29b82e5937b433b..33e5f2e9ed626355d80c90e2b16544277c852045 100644
--- a/components/update_client/update_engine.h
+++ b/components/update_client/update_engine.h
@@ -77,6 +77,8 @@ class UpdateEngine {
   // TODO(sorin): refactor as a ref counted class.
   PingManager* ping_manager_;  // Not owned by this class.
 
+  std::unique_ptr<PersistedData> metadata_;
+
   // Called when CRX state changes occur.
   const NotifyObserversCallback notify_observers_callback_;