Host state power on and off support

This supports the basic systemd transitions to power on and
off a host.  Future commits will handle monitoring for the
state transition to finish and updating the current state.

Change-Id: I1ada1f4e7bd2844db49e63aaaf5b64c88b4af127
Signed-off-by: Andrew Geissler <andrewg@us.ibm.com>
diff --git a/host_state_manager.hpp b/host_state_manager.hpp
index d1f17d4..8f0733b 100644
--- a/host_state_manager.hpp
+++ b/host_state_manager.hpp
@@ -58,6 +58,15 @@
         HostState currentHostState(HostState value) override;
 
     private:
+        /** @brief Execute the transition request
+         *
+         * This function assumes the state has been validated and the host
+         * is in an appropriate state for the transition to be started.
+         *
+         * @param[in] tranReq    - Transition requested
+         */
+        void executeTransition(Transition tranReq);
+
         /** @brief Persistent sdbusplus DBus bus connection. */
         sdbusplus::bus::bus& bus;
 };