Factor out duplicated GioMemoryFileSnapshotCtor() + NaClAppLoadFile() calls

tests/signal_handler_single_step/regs_step_test_host.c

Index: tests/signal_handler_single_step/regs_step_test_host.c
diff --git a/tests/signal_handler_single_step/regs_step_test_host.c b/tests/signal_handler_single_step/regs_step_test_host.c
index 354b1e220c94fda97992b0ec0468fb61a3424b07..521feafdb452824834e150eb8df7412182b8cb26 100644
--- a/tests/signal_handler_single_step/regs_step_test_host.c
+++ b/tests/signal_handler_single_step/regs_step_test_host.c
@@ -9,12 +9,12 @@
 
 #include "native_client/src/include/nacl_assert.h"
 #include "native_client/src/include/portability_io.h"
-#include "native_client/src/shared/gio/gio.h"
 #include "native_client/src/shared/platform/nacl_check.h"
 #include "native_client/src/shared/platform/nacl_exit.h"
 #include "native_client/src/shared/platform/nacl_log.h"
 #include "native_client/src/trusted/service_runtime/include/bits/mman.h"
 #include "native_client/src/trusted/service_runtime/include/bits/nacl_syscalls.h"
+#include "native_client/src/trusted/service_runtime/load_file.h"
 #include "native_client/src/trusted/service_runtime/nacl_all_modules.h"
 #include "native_client/src/trusted/service_runtime/nacl_app.h"
 #include "native_client/src/trusted/service_runtime/nacl_app_thread.h"
@@ -22,7 +22,6 @@
 #include "native_client/src/trusted/service_runtime/nacl_signal.h"
 #include "native_client/src/trusted/service_runtime/nacl_syscall_common.h"
 #include "native_client/src/trusted/service_runtime/nacl_syscall_handlers.h"
-#include "native_client/src/trusted/service_runtime/nacl_valgrind_hooks.h"
 #include "native_client/src/trusted/service_runtime/sel_ldr.h"
 #include "native_client/src/trusted/service_runtime/thread_suspension_unwind.h"
 #include "native_client/tests/common/register_set.h"
@@ -156,7 +155,6 @@ static enum NaClSignalResult TrapSignalHandler(int signal, void *ucontext) {
 
 int main(int argc, char **argv) {
   struct NaClApp app;
-  struct GioMemoryFileSnapshot gio_file;
   uint32_t mmap_addr;
   char arg_string[32];
   char *args[] = {"prog_name", arg_string};
@@ -169,10 +167,8 @@ int main(int argc, char **argv) {
 
   NaClAddSyscall(NACL_sys_test_syscall_1, TestSyscall);
 
-  NaClFileNameForValgrind(argv[1]);
-  CHECK(GioMemoryFileSnapshotCtor(&gio_file, argv[1]));
   CHECK(NaClAppCtor(&app));
-  CHECK(NaClAppLoadFile((struct Gio *) &gio_file, &app) == LOAD_OK);
+  CHECK(NaClAppLoadFileFromFilename(&app, argv[1]) == LOAD_OK);
   NaClAppInitialDescriptorHookup(&app);
   CHECK(NaClAppPrepareToLaunch(&app) == LOAD_OK);