Use request initiator to check for cross origin requests.

content/browser/service_worker/foreign_fetch_request_handler.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/service_worker/foreign_fetch_request_handler.h"
 
 #include "base/macros.h"
 #include "content/browser/service_worker/service_worker_context_wrapper.h"
 #include "content/browser/service_worker/service_worker_url_request_job.h"
 #include "content/common/resource_request_body.h"
@@ skipping 196 matching lines @@
     ServiceWorkerMetrics::URLRequestJobResult* result) {
   // TODO(mek): Figure out what should happen if the active worker changes or
   // gets uninstalled before this point is reached.
   if (!target_worker_) {
     *result = ServiceWorkerMetrics::REQUEST_JOB_ERROR_NO_ACTIVE_VERSION;
     return nullptr;
   }
   return target_worker_.get();
 }
 
-GURL ForeignFetchRequestHandler::GetRequestingOrigin() {
-  // TODO(mek): Implement this.
-  return GURL();
-}
-
 void ForeignFetchRequestHandler::ClearJob() {
   job_.reset();
   target_worker_ = nullptr;
 }
 
 }  // namespace content