Add a test for IdleTimerController.

Bug: 28362720
Test: bullhead builds,boots
Test: netd_{unit,integration}_test pass
Change-Id: I0e3c2462676969b26a4cbee7aa6552078fde90f5
diff --git a/server/IdletimerController.h b/server/IdletimerController.h
index 98a312e..33abdb6 100644
--- a/server/IdletimerController.h
+++ b/server/IdletimerController.h
@@ -16,6 +16,8 @@
 #ifndef _IDLETIMER_CONTROLLER_H
 #define _IDLETIMER_CONTROLLER_H
 
+#include <stdint.h>
+
 class IdletimerController {
 public:
 
@@ -39,6 +41,9 @@
     int runIpxtablesCmd(int argc, const char **cmd);
     int modifyInterfaceIdletimer(IptOp op, const char *iface, uint32_t timeout,
                                  const char *classLabel);
+
+    friend class IdletimerControllerTest;
+    static int (*execFunction)(int, char **, int *, bool, bool);
 };
 
 #endif