Extract CreateInitProcessReaper() from the Zygote.

sandbox/linux/suid/client/setuid_sandbox_client.h

 // 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.
 
 #ifndef SANDBOX_LINUX_SUID_SETUID_SANDBOX_CLIENT_H_
 #define SANDBOX_LINUX_SUID_SETUID_SANDBOX_CLIENT_H_
 
 #include "base/basictypes.h"
+#include "base/callback_forward.h"
 
 namespace base { class Environment; }
 
 namespace sandbox {
 
 // Helper class to use the setuid sandbox. This class is to be used both
 // before launching the setuid helper and after being executed through the
 // setuid helper.
 //
 // A typical use would be:
 // 1. The browser calls SetupLaunchEnvironment()
 // 2. The browser launches a renderer through the setuid sandbox.
 // 3. The renderer requests being chroot-ed through ChrootMe() and
 //    requests other sandboxing status via the status functions.
 class SetuidSandboxClient {
  public:
   // All instantation should go through this factory method.
   static class SetuidSandboxClient* Create();
   ~SetuidSandboxClient();
 
   // Ask the setuid helper over the setuid sandbox IPC channel to chroot() us
   // to an empty directory.
   // Will only work if we have been launched through the setuid helper.
   bool ChrootMe();
+  // When a new PID namespace is created, the process with pid == 1 should
+  // assume the role of init.
+  // See sandbox/linux/services/init_process_reaper.h for more information
+  // on this API.
+  bool CreateInitProcessReaper(base::Closure* post_fork_parent_callback);
 
   // Did we get launched through an up to date setuid binary ?
   bool IsSuidSandboxUpToDate() const;
   // Did we get launched through the setuid helper ?
   bool IsSuidSandboxChild() const;
   // Did the setuid helper create a new PID namespace ?
   bool IsInNewPIDNamespace() const;
   // Did the setuid helper create a new network namespace ?
   bool IsInNewNETNamespace() const;
   // Are we done and fully sandboxed ?
   bool IsSandboxed() const;
 
   // Set-up the environment. This should be done prior to launching the setuid
   // helper.
   void SetupLaunchEnvironment();
 
  private:
   // Holds the environment. Will never be NULL.
   base::Environment* env_;
   bool sandboxed_;
   DISALLOW_IMPLICIT_CONSTRUCTORS(SetuidSandboxClient);
 };
 
 }  // namespace sandbox
 
 #endif  // SANDBOX_LINUX_SUID_SETUID_SANDBOX_CLIENT_H_