NaCl: Clean up how FDs are passed to nacl_helper instances on Linux

components/nacl/zygote/nacl_fork_delegate_linux.cc

 // Copyright (c) 2012 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 "components/nacl/zygote/nacl_fork_delegate_linux.h"
 
 #include <signal.h>
 #include <stdlib.h>
 #include <sys/resource.h>
 #include <sys/socket.h>
@@ skipping 240 matching lines @@
     return false;
   *uma_name = "NaCl.Client.Helper.StateOnFork";
   *uma_sample = status_;
   *uma_boundary_value = kNaClHelperStatusBoundary;
   return status_ == kNaClHelperSuccess;
 }
 
 pid_t NaClForkDelegate::Fork(const std::vector<int>& fds) {
   VLOG(1) << "NaClForkDelegate::Fork";
 
-  DCHECK(fds.size() == kNaClParentFDIndex + 1);
+  DCHECK(fds.size() == kNumPassedFDs);
 
   // First, send a remote fork request.
   Pickle write_pickle;
   write_pickle.WriteInt(kNaClForkRequest);
 
   char reply_buf[kNaClMaxIPCMessageLength];
   ssize_t reply_size = 0;
   bool got_reply =
       SendIPCRequestAndReadReply(fd_, fds, write_pickle,
                                  reply_buf, sizeof(reply_buf), &reply_size);
@@ skipping 60 matching lines @@
   int remote_exit_code;
   if (!iter.ReadInt(&remote_exit_code)) {
     LOG(ERROR) << "GetTerminationStatus: pickle failed";
     return false;
   }
 
   *status = static_cast<base::TerminationStatus>(termination_status);
   *exit_code = remote_exit_code;
   return true;
 }