network_manager: Add support for non-disruptive reconfiguration

This makes it possible for network interfaces to non-disruptively reload
configurations and tell systemd-networkd to reconfigure interaces.

Change-Id: Ia4003854b6fe845a67b954068ec363bc4c622837
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/network_manager.hpp b/src/network_manager.hpp
index 12b3d7d..ceb62c4 100644
--- a/src/network_manager.hpp
+++ b/src/network_manager.hpp
@@ -132,6 +132,10 @@
      */
     virtual void restartSystemdUnit(const std::string& unit);
 
+    /** @brief Tell systemd-network to reload all of the network configurations
+     */
+    virtual void reloadConfigs();
+
     /** @brief Returns the number of interfaces under this manager.
      *
      * @return the number of interfaces managed by this manager.