Have content/ create and destroy its own threads.

chrome/browser/chrome_browser_parts_gtk.h

Index: chrome/browser/chrome_browser_parts_gtk.h
diff --git a/chrome/browser/chrome_browser_parts_gtk.h b/chrome/browser/chrome_browser_parts_gtk.h
index 8a193213e6d037e87ee4bbfc96530dc6cf38e7ae..29ecf6454a7e3b01e3aaf2b3173ed36cbda26df5 100644
--- a/chrome/browser/chrome_browser_parts_gtk.h
+++ b/chrome/browser/chrome_browser_parts_gtk.h
@@ -9,6 +9,7 @@
 #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 {
@@ -21,8 +22,12 @@ class ChromeBrowserPartsGtk : public content::BrowserMainParts {
   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);