login_manager: Add dbus API for restarting entd when enterprise extensions installed

session_manager_service.h

Index: session_manager_service.h
diff --git a/session_manager_service.h b/session_manager_service.h
index a75c50b6931db1087659b1af9cdbb0d2f596365b..12fbb094058a6ae6a6729c09a2fee4a00f569163 100644
--- a/session_manager_service.h
+++ b/session_manager_service.h
@@ -270,6 +270,10 @@ class SessionManagerService : public chromeos::dbus::AbstractDbusService {
                       gboolean* OUT_done,
                       GError** error);
 
+  // Restarts (or starts if stopped) the entd upstart job.  Returns if
+  // start was successful.
+  gboolean RestartEntd(GError** error);
+
   // Perform very, very basic validation of |email_address|.
   static bool ValidateEmail(const std::string& email_address);