Add persistency for events

Persist event D-bus objects using cereal

Resolves openbmc/openbmc#2319

Change-Id: Ifa15d944fe1d1026761f65eeb647dcbdf6afdba0
Signed-off-by: Dhruvaraj Subhashchandran <dhruvaraj@in.ibm.com>
diff --git a/src/event_manager.hpp b/src/event_manager.hpp
index a177739..a4ccf18 100644
--- a/src/event_manager.hpp
+++ b/src/event_manager.hpp
@@ -38,6 +38,11 @@
                 const std::string& objectPath, const std::string& propertyName,
                 const std::string& propertyValue);
 
+    /** @brief Construct event d-bus objects from their persisted
+     *         representations.
+     */
+    void restore();
+
   private:
     using EventName = std::string;
     /** @brief Queue of events */