Revert of Make SandboxIPCProcess a thread.

content/public/browser/zygote_host_linux.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 CONTENT_PUBLIC_BROWSER_ZYGOTE_HOST_LINUX_H_
 #define CONTENT_PUBLIC_BROWSER_ZYGOTE_HOST_LINUX_H_
 
 #include <unistd.h>
 
 #include "base/process/process.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
 // http://code.google.com/p/chromium/wiki/LinuxZygote
 
 // The zygote host is the interface, in the browser process, to the zygote
 // process.
 class ZygoteHost {
  public:
   // Returns the singleton instance.
   CONTENT_EXPORT static ZygoteHost* GetInstance();
 
   virtual ~ZygoteHost() {}
 
   // Returns the pid of the Zygote process.
   virtual pid_t GetPid() const = 0;
 
+  // Returns the pid of the Sandbox Helper process.
+  virtual pid_t GetSandboxHelperPid() const = 0;
+
   // Returns an int which is a bitmask of kSandboxLinux* values. Only valid
   // after the first render has been forked.
   virtual int GetSandboxStatus() const = 0;
 
   // Adjust the OOM score of the given renderer's PID.  The allowed
   // range for the score is [0, 1000], where higher values are more
   // likely to be killed by the OOM killer.
   virtual void AdjustRendererOOMScore(base::ProcessHandle process_handle,
                                       int score) = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_ZYGOTE_HOST_LINUX_H_