Have content/ create and destroy its own threads.

content/public/browser/browser_main_parts.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_PUBLIC_BROWSER_BROWSER_MAIN_PARTS_H_
 #define CONTENT_PUBLIC_BROWSER_BROWSER_MAIN_PARTS_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "content/common/content_export.h"
+#include "content/public/browser/browser_thread.h"
 
 namespace content {
 
 // This class contains different "stages" to be executed by |BrowserMain()|,
 // Each stage is represented by a single BrowserMainParts method, called from
 // the corresponding method in |BrowserMainLoop| (e.g., EarlyInitialization())
 // which does the following:
 //  - calls a method (e.g., "PreEarlyInitialization()") which implements
 //    platform / tookit specific code for that stage.
 //  - calls various methods for things common to all platforms (for that stage).
@@ skipping 36 matching lines @@
 
   virtual void PostEarlyInitialization() = 0;
 
   virtual void PreMainMessageLoopStart() = 0;
 
   virtual void PostMainMessageLoopStart() = 0;
 
   // Allows an embedder to do any extra toolkit initialization.
   virtual void ToolkitInitialized() = 0;
 
+  // Child threads have not been created at this point.
   virtual void PreMainMessageLoopRun() = 0;
 
+  // The various browser threads have been created at this point.
+  virtual void PreMainMessageLoopRunThreadsCreated() = 0;
+
   // Returns true if the message loop was run, false otherwise.
   // If this returns false, the default implementation will be run.
   // May set |result_code|, which will be returned by |BrowserMain()|.
   virtual bool MainMessageLoopRun(int* result_code) = 0;
 
+  // This happens after the main message loop has stopped, but before
+  // threads are stopped.
   virtual void PostMainMessageLoopRun() = 0;
 
+  // Called once for each thread owned by the content framework just
+  // before and just after it is torn down. This is in reverse order
+  // of the threads' appearance in the BrowserThread::ID enumeration.
+  // Note that you will not receive such a call for BrowserThread::UI,
+  // since it is the main thread of the application.
+  virtual void PreStopThread(BrowserThread::ID identifier) = 0;
+  virtual void PostStopThread(BrowserThread::ID identifier) = 0;
+
+  // Called as the very last part of shutdown.
+  virtual void FinalCleanup() = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(BrowserMainParts);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_BROWSER_MAIN_PARTS_H_