Have content/ create and destroy its own threads.

chrome/browser/chrome_browser_parts_gtk.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.
 
 // Contains functions used by BrowserMain() that are gtk-specific.
 
 #ifndef CHROME_BROWSER_CHROME_BROWSER_PARTS_GTK_H_
 #define CHROME_BROWSER_CHROME_BROWSER_PARTS_GTK_H_
 #pragma once
 
 #include "base/compiler_specific.h"
+#include "content/public/browser/browser_thread.h"
 #include "content/public/browser/browser_main_parts.h"
 
 class ChromeBrowserPartsGtk : public content::BrowserMainParts {
  public:
   ChromeBrowserPartsGtk();
 
   virtual void PreEarlyInitialization() OVERRIDE;
   virtual void PostEarlyInitialization() OVERRIDE {}
   virtual void PreMainMessageLoopStart() OVERRIDE {}
   virtual void ToolkitInitialized() OVERRIDE {}
   virtual void PostMainMessageLoopStart() OVERRIDE {}
   virtual void PreMainMessageLoopRun() OVERRIDE {}
+  virtual void PreMainMessageLoopRunThreadsCreated() OVERRIDE {}
   virtual bool MainMessageLoopRun(int* result_code) OVERRIDE;
-  virtual void PostMainMessageLoopRun() {}
+  virtual void PostMainMessageLoopRun() OVERRIDE {}
+  virtual void PreStopThread(content::BrowserThread::ID) OVERRIDE {}
+  virtual void PostStopThread(content::BrowserThread::ID) OVERRIDE {}
+  virtual void FinalCleanup() OVERRIDE {}
 
   static void ShowMessageBox(const char* message);
 
  private:
   void DetectRunningAsRoot();
 };
 
 #endif  // CHROME_BROWSER_CHROME_BROWSER_PARTS_GTK_H_