Have content/ create and destroy its own threads.

chrome/browser/chrome_browser_parts_aura.h

Index: chrome/browser/chrome_browser_parts_aura.h
diff --git a/chrome/browser/chrome_browser_parts_aura.h b/chrome/browser/chrome_browser_parts_aura.h
index dbc9d76567d7ac955188e0842a2823e91afe71b7..727aa16ba72783a91eb8d64ad677034ceeaecf44 100644
--- a/chrome/browser/chrome_browser_parts_aura.h
+++ b/chrome/browser/chrome_browser_parts_aura.h
@@ -8,6 +8,11 @@
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "content/public/browser/browser_main_parts.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace content {
+class IOThreadDelegate;
+}
 
 class ChromeBrowserPartsAura : public content::BrowserMainParts {
  public:
@@ -18,9 +23,13 @@ class ChromeBrowserPartsAura : public content::BrowserMainParts {
   virtual void ToolkitInitialized() OVERRIDE;
   virtual void PreMainMessageLoopStart() OVERRIDE;
   virtual void PostMainMessageLoopStart() OVERRIDE;
-  virtual void PreMainMessageLoopRun() OVERRIDE;
+  virtual content::IOThreadDelegate* PreMainMessageLoopRun() OVERRIDE;
+  virtual void PreMainMessageLoopRunThreadsCreated() OVERRIDE {}
   virtual bool MainMessageLoopRun(int* result_code) OVERRIDE;
   virtual void PostMainMessageLoopRun() OVERRIDE;
+  virtual void PreStopThread(BrowserThread::ID identifier) OVERRIDE {}
+  virtual void PostStopThread(BrowserThread::ID identifier) OVERRIDE {}
+  virtual void FinalCleanup() OVERRIDE {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ChromeBrowserPartsAura);