Provide chrome the option of learning the debug stub port chosen by nacl.

src/trusted/service_runtime/sel_ldr.h

 /*
  * Copyright (c) 2012 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.
  */
 
 /*
  * NaCl Simple/secure ELF loader (NaCl SEL).
  *
  * This loader can only process NaCl object files as produced using
@@ skipping 373 matching lines @@
    * any per-thread lock (natp->mu).
    */
   struct NaClMutex          threads_mu;
   struct DynArray           threads;   /* NaClAppThread pointers */
   int                       num_threads;  /* number actually running */
 
   struct NaClFastMutex      desc_mu;
   struct DynArray           desc_tbl;  /* NaClDesc pointers */
 
   const struct NaClDebugCallbacks *debug_stub_callbacks;
+  uint16_t                        debug_stub_port;
   struct NaClDesc                 *main_nexe_desc;
   struct NaClDesc                 *irt_nexe_desc;
 
   struct NaClMutex          exception_mu;
   uint32_t                  exception_handler;
   int                       enable_exception_handling;
 #if NACL_WINDOWS
   enum NaClDebugExceptionHandlerState debug_exception_handler_state;
   NaClAttachDebugExceptionHandlerFunc attach_debug_exception_handler_func;
 #endif
@@ skipping 488 matching lines @@
 #else
 static INLINE void NaClHandleBootstrapArgs(int *argc_p, char ***argv_p) {
   UNREFERENCED_PARAMETER(argc_p);
   UNREFERENCED_PARAMETER(argv_p);
 }
 #endif
 
 EXTERN_C_END
 
 #endif  /* NATIVE_CLIENT_SRC_TRUSTED_SERVICE_RUNTIME_SEL_LDR_H_ */