Have content/ create and destroy its own threads.

content/browser/browser_process_io_thread.h

+// 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_BROWSER_BROWSER_PROCESS_IO_THREAD_H_
+#define CONTENT_BROWSER_BROWSER_PROCESS_IO_THREAD_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "content/browser/browser_process_sub_thread.h"
+#include "content/public/browser/io_thread_delegate.h"
+
+namespace content {
+
+class BrowserProcessIOThread : public BrowserProcessSubThread {
+ public:
+  BrowserProcessIOThread(IOThreadDelegate* delegate);
+  virtual ~BrowserProcessIOThread();
+
+  virtual void Init() OVERRIDE;
+  virtual void CleanUp() OVERRIDE;
+
+ private:
+  IOThreadDelegate* delegate_;
+  DISALLOW_COPY_AND_ASSIGN(BrowserProcessIOThread);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_BROWSER_PROCESS_IO_THREAD_H_