Expose NaClAppSetDesc() to Chromium for use at startup

src/trusted/service_runtime/sel_ldr.c

Index: src/trusted/service_runtime/sel_ldr.c
diff --git a/src/trusted/service_runtime/sel_ldr.c b/src/trusted/service_runtime/sel_ldr.c
index 662138c4182d2a99dd0997608d99fc2f1e824295..01f6c48c52a89be1531424072cf3457dc281579d 100644
--- a/src/trusted/service_runtime/sel_ldr.c
+++ b/src/trusted/service_runtime/sel_ldr.c
@@ -15,6 +15,7 @@
 #include "native_client/src/include/nacl_macros.h"
 
 #include "native_client/src/public/desc_metadata_types.h"
+#include "native_client/src/public/nacl_app.h"
 #include "native_client/src/public/secure_service.h"
 
 #include "native_client/src/shared/gio/gio.h"
@@ -78,6 +79,9 @@ int NaClAppWithSyscallTableCtor(struct NaClApp               *nap,
                                 struct NaClSyscallTableEntry *table) {
   struct NaClDescEffectorLdr  *effp;
 
+  /* Zero-initialize in case we miss any fields below. */
+  memset(nap, 0, sizeof(*nap));
+
   /* The validation cache will be injected later, if it exists. */
   nap->validation_cache = NULL;
 
@@ -333,6 +337,15 @@ int NaClAppCtor(struct NaClApp *nap) {
   return NaClAppWithSyscallTableCtor(nap, nacl_syscall);
 }
 
+struct NaClApp *NaClAppCreate(void) {
+  struct NaClApp *nap = malloc(sizeof(struct NaClApp));
+  if (nap == NULL)
+    NaClLog(LOG_FATAL, "Failed to allocate NaClApp\n");
+  if (!NaClAppCtor(nap))
+    NaClLog(LOG_FATAL, "NaClAppCtor() failed\n");
+  return nap;
+}
+
 /*
  * unaligned little-endian load.  precondition: nbytes should never be
  * more than 8.