Set up content in-process main threads via factory

content/browser/utility_process_host_impl.h

Index: content/browser/utility_process_host_impl.h
diff --git a/content/browser/utility_process_host_impl.h b/content/browser/utility_process_host_impl.h
index 6eecd3d89855cb58d10cf3f922cbba549620c84a..5443e09bfe531116e955ff0931c55f7bc4fa83d9 100644
--- a/content/browser/utility_process_host_impl.h
+++ b/content/browser/utility_process_host_impl.h
@@ -18,11 +18,11 @@
 
 namespace base {
 class SequencedTaskRunner;
+class Thread;
 }
 
 namespace content {
 class BrowserChildProcessHostImpl;
-class UtilityMainThread;
 
 class CONTENT_EXPORT UtilityProcessHostImpl
     : public NON_EXPORTED_BASE(UtilityProcessHost),
@@ -83,10 +83,8 @@ class CONTENT_EXPORT UtilityProcessHostImpl
 
   scoped_ptr<BrowserChildProcessHostImpl> process_;
 
-#if !defined(CHROME_MULTIPLE_DLL)
   // Used in single-process mode instead of process_.
-  scoped_ptr<UtilityMainThread> in_process_thread_;
-#endif
+  scoped_ptr<base::Thread> in_process_thread_;
 
   DISALLOW_COPY_AND_ASSIGN(UtilityProcessHostImpl);
 };