Modify the Chrome Linux zygote to support a nacl_helper executable,

content/common/zygote_fork_delegate_linux.h

Index: content/common/zygote_fork_delegate_linux.h
diff --git a/content/common/zygote_fork_delegate_linux.h b/content/common/zygote_fork_delegate_linux.h
new file mode 100644
index 0000000000000000000000000000000000000000..26dfbc919d1d82111706f336893115db4ec9980e
--- /dev/null
+++ b/content/common/zygote_fork_delegate_linux.h
@@ -0,0 +1,49 @@
+// 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 CONTENT_COMMON_ZYGOTE_FORK_DELEGATE_LINUX_H_
+#define CONTENT_COMMON_ZYGOTE_FORK_DELEGATE_LINUX_H_
+#pragma once
+
+#include <unistd.h>
+
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+
+// The ZygoteForkDelegate allows the Chrome Linux zygote to delegate
+// fork operations to another class that knows how to do some
+// specialized version of fork.
+class ZygoteForkDelegate {
+ public:
+  // A ZygoteForkDelegate is created during Chrome linux zygote
+  // initialization, and provides "fork()" functionality with
+  // as an alternative to forking the zygote. A new delegate is
+  // passed in as an argument to ZygoteMain().
+  ZygoteForkDelegate() {}
+  virtual ~ZygoteForkDelegate() {}
+
+  // Initialization happens in the zygote after it has been
+  // started by ZygoteMain.
+  virtual void Init(bool sandboxed,
+                    int browserdesc,
+                    int sandboxdesc) = 0;
+
+  // Returns 'true' if the delegate would like to handle a given
+  // fork request. Otherwise returns false.
+  virtual bool CanHelp(const std::string& process_type) = 0;
+
+  // Delegate forks, returning a -1 on failure. Outside the
+  // suid sandbox, Fork() returns the Linux process ID. Inside
+  // the sandbox, returns a positive integer, with PID discovery
+  // handled by the sandbox.
+  virtual pid_t Fork(const std::vector<int>& fds) = 0;
+
+  // After a successful for, signal the child to indicate that
+  // the child's PID has been received. Also communicate the
+  // channel switch as a part of acknowledgement message.
+  virtual bool AckChild(int fd, const std::string& channel_switch) = 0;
+};
+#endif  // CONTENT_COMMON_ZYGOTE_FORK_DELEGATE_LINUX_H_