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

src/public/chrome_main.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.
  */
 
 #ifndef NATIVE_CLIENT_SRC_PUBLIC_CHROME_MAIN_H_
 #define NATIVE_CLIENT_SRC_PUBLIC_CHROME_MAIN_H_ 1
 
 #include "native_client/src/include/nacl_base.h"
@@ skipping 83 matching lines @@
 #if NACL_LINUX || NACL_OSX
   /*
    * Server socket that will be used by debug stub to accept connections
    * from NaCl GDB.  This socket descriptor has already had bind() and listen()
    * called on it.  Optional; may be -1.
    */
   int debug_stub_server_bound_socket_fd;
 #endif
 
   /*
+   * Callback called when debug stub port is known.  Optional; may be NULL.
+   */
+  void (*debug_stub_server_port_selected_handler_func)(uint16_t port);
+
+  /*
    * Callback to use for creating shared memory objects.  Optional;
    * may be NULL.
    */
   NaClCreateMemoryObjectFunc create_memory_object_func;
 
   /* Cache for NaCl validation judgements.  Optional; may be NULL. */
   struct NaClValidationCache *validation_cache;
 
 #if NACL_WINDOWS
   /*
@@ skipping 80 matching lines @@
 /*
  * DEPRECATED. Calls NaClChromeMainLoad and NaClChromeMainStart.
  * TODO(teravest): Remove this old interface after current users are migrated.
  */
 void NaClChromeMainStartApp(struct NaClApp *nap,
                             struct NaClChromeMainArgs *args);
 
 EXTERN_C_END
 
 #endif