Make a NaClDesc ctor for creating descs from NaClFileInfo.

src/public/nacl_file_info.h

 /*
  * Copyright (c) 2013 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
-#ifndef NATIVE_CLIENT_SRC_TRUSTED_REVERSE_SERVICE_NACL_FILE_INFO_H_
-#define NATIVE_CLIENT_SRC_TRUSTED_REVERSE_SERVICE_NACL_FILE_INFO_H_
+#ifndef NATIVE_CLIENT_SRC_PUBLIC_NACL_FILE_INFO_H_
+#define NATIVE_CLIENT_SRC_PUBLIC_NACL_FILE_INFO_H_
 
 #include "native_client/src/include/nacl_base.h"
 #include "native_client/src/include/portability.h"
 
 EXTERN_C_BEGIN
 
 /*
  * NaClFileToken is a single-use nonce that the NaCl process can use to query
  * the browser process for trusted information about a file.  lo == 0 && hi == 0
  * indicates the token is invalid and no additional information is available.
  */
 struct NaClFileToken {
   uint64_t lo;
   uint64_t hi;
 };
 
 struct NaClFileInfo {
   /* desc is either a Unix file descriptor or a Windows file handle. */
   int32_t desc;
   struct NaClFileToken file_token;
 };
 
 EXTERN_C_END
 
-#endif /* NATIVE_CLIENT_SRC_TRUSTED_REVERSE_SERVICE_NACL_FILE_INFO_H_ */
+#endif /* NATIVE_CLIENT_SRC_PUBLIC_NACL_FILE_INFO_H_ */