Enable compiling GN by default.

tools/gn/function_exec_script.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/process/kill.h"
 #include "base/process/launch.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 147 matching lines @@
   if (pipe(pipe_fd) < 0)
     return false;
 
   switch (pid = fork()) {
     case -1:  // error
       close(pipe_fd[0]);
       close(pipe_fd[1]);
       return false;
     case 0:  // child
       {
-#if defined(OS_MACOSX)
-        base::RestoreDefaultExceptionHandler();
-#endif
         // DANGER: no calls to malloc are allowed from now on:
         // http://crbug.com/36678
 
         // Obscure fork() rule: in the child, if you don't end up doing exec*(),
         // you call _exit() instead of exit(). This is because _exit() does not
         // call any previously-registered (in the parent) exit handlers, which
         // might do things like block waiting for threads that don't even exist
         // in the child.
         int dev_null = open("/dev/null", O_WRONLY);
         if (dev_null < 0)
@@ skipping 202 matching lines @@
       msg += ".";
     *err = Err(function->function(), "Script returned non-zero exit code.",
                msg);
     return Value();
   }
 
   return ConvertInputToValue(output, function, args[2], err);
 }
 
 }  // namespace functions