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

net/url_request/url_request.cc

Index: net/url_request/url_request.cc
===================================================================
--- net/url_request/url_request.cc	(revision 23443)
+++ net/url_request/url_request.cc	(working copy)
@@ -266,12 +266,6 @@
   job_->Start();
 }
 
-void URLRequest::Restart() {
-  // Should only be called if the original job didn't make any progress.
-  DCHECK(job_ && !job_->has_response_started());
-  RestartWithJob(GetJobManager()->CreateJob(this));
-}
-
 void URLRequest::RestartWithJob(URLRequestJob *job) {
   DCHECK(job->request() == this);
   PrepareToRestart();