Set up content in-process main threads via factory

content/browser/renderer_host/render_process_host_impl.h

Index: content/browser/renderer_host/render_process_host_impl.h
diff --git a/content/browser/renderer_host/render_process_host_impl.h b/content/browser/renderer_host/render_process_host_impl.h
index 72ec846303d4dfdbf235269b91884270dfa014e6..9d195f59a60d7e4d5a8df42c1b602648e0ab6b5c 100644
--- a/content/browser/renderer_host/render_process_host_impl.h
+++ b/content/browser/renderer_host/render_process_host_impl.h
@@ -264,10 +264,8 @@ class CONTENT_EXPORT RenderProcessHostImpl
   // This is used to clear our cache five seconds after the last use.
   base::DelayTimer<RenderProcessHostImpl> cached_dibs_cleaner_;
 
-#if !defined(CHROME_MULTIPLE_DLL)
   // Used in single-process mode.
-  scoped_ptr<RendererMainThread> in_process_renderer_;
-#endif
+  scoped_ptr<base::Thread> in_process_renderer_;
 
   // True after Init() has been called. We can't just check channel_ because we
   // also reset that in the case of process termination.