Make a NaClDesc ctor for creating descs from NaClFileInfo.

src/trusted/desc/nacl_desc_wrapper.cc

Index: src/trusted/desc/nacl_desc_wrapper.cc
diff --git a/src/trusted/desc/nacl_desc_wrapper.cc b/src/trusted/desc/nacl_desc_wrapper.cc
index ada9cb3aad152810f52670b829e4925ed1652c11..ba12aae53fde37c7c9222f43aa09bb70e41a6d57 100644
--- a/src/trusted/desc/nacl_desc_wrapper.cc
+++ b/src/trusted/desc/nacl_desc_wrapper.cc
@@ -16,6 +16,7 @@
 #endif  // defined(NACL_LINUX)
 #include "native_client/src/trusted/desc/nacl_desc_base.h"
 #include "native_client/src/trusted/desc/nacl_desc_conn_cap.h"
+#include "native_client/src/trusted/desc/nacl_desc_file_token.h"
 #include "native_client/src/trusted/desc/nacl_desc_imc.h"
 #include "native_client/src/trusted/desc/nacl_desc_imc_shm.h"
 #include "native_client/src/trusted/desc/nacl_desc_invalid.h"
@@ -315,6 +316,21 @@ DescWrapper* DescWrapperFactory::MakeFileDesc(int host_os_desc, int mode) {
   return MakeGenericCleanup(desc);
 }
 
+DescWrapper* DescWrapperFactory::MakeFileDescMetadata(struct NaClFileInfo info,
+                                                      int mode) {
+  struct NaClDesc* desc = ImportHostDescCommon(info.desc, mode);
+  if (NULL == desc) {
+    return NULL;
+  }
+  if (NaClFileTokenIsValid(&info.file_token)) {
+    if (!NaClDescSetFileToken(desc, &info.file_token)) {
+      NaClDescSafeUnref(desc);
+      return NULL;
+    }
+  }
+  return MakeGenericCleanup(desc);
+}
+
 DescWrapper* DescWrapperFactory::MakeFileDescQuota(int host_os_desc,
                                                    int mode,
                                                    const uint8_t* file_id) {