Remove URLRequest::Restart() because it is only referenced by unit tests

net/url_request/url_request_job.h

Index: net/url_request/url_request_job.h
===================================================================
--- net/url_request/url_request_job.h	(revision 23443)
+++ net/url_request/url_request_job.h	(working copy)
@@ -240,10 +240,6 @@
   // we were canceled.
   void NotifyCanceled();
 
-  // Notifies the job the request should be restarted.
-  // Should only be called if the job has not started a resposne.
-  void NotifyRestartRequired();
-
   // Called to get more data from the request response. Returns true if there
   // is data immediately available to read. Return false otherwise.
   // Internally this function may initiate I/O operations to get more data.