For Linux, create a ZygoteForkDelegate that uses the nacl_helper executable

chrome/nacl/nacl_listener.h

Index: chrome/nacl/nacl_listener.h
diff --git a/chrome/nacl/nacl_listener.h b/chrome/nacl/nacl_listener.h
new file mode 100644
index 0000000000000000000000000000000000000000..2434268e9ba1cd4b5613c76ec39deb2bf4baf9bd
--- /dev/null
+++ b/chrome/nacl/nacl_listener.h
@@ -0,0 +1,31 @@
+// Copyright (c) 2011 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.
+
+#ifndef CHROME_NACL_NACL_LISTENER_H_
+#define CHROME_NACL_NACL_LISTENER_H_
+#pragma once
+
+#include <vector>
+
+#include "chrome/common/nacl_types.h"
+#include "ipc/ipc_channel.h"
+
+// The NaClListener is an IPC channel listener that waits for a
+// request to start a NaCl module.
+class NaClListener : public IPC::Channel::Listener {
+ public:
+  NaClListener();
+  ~NaClListener();
+  // Listen for a request to launch a NaCl module.
+  void Listen();
+
+ private:
+  void OnStartSelLdr(std::vector<nacl::FileDescriptor> handles,
+                     bool have_irt_file);
+  virtual bool OnMessageReceived(const IPC::Message& msg);
+
+  DISALLOW_COPY_AND_ASSIGN(NaClListener);
+};
+
+#endif  // CHROME_NACL_NACL_LISTENER_H_