Revert of Stop passing const-reference of SWRegistration in all GetRegistrationsCallbacks.

content/browser/push_messaging/push_messaging_router.cc

 // Copyright 2014 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/push_messaging/push_messaging_router.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "content/browser/service_worker/service_worker_context_wrapper.h"
@@ skipping 55 matching lines @@
       service_worker_registration_id, origin,
       base::Bind(&PushMessagingRouter::FindServiceWorkerRegistrationCallback,
                  payload, deliver_message_callback));
 }
 
 // static
 void PushMessagingRouter::FindServiceWorkerRegistrationCallback(
     const PushEventPayload& payload,
     const DeliverMessageCallback& deliver_message_callback,
     ServiceWorkerStatusCode service_worker_status,
-    scoped_refptr<ServiceWorkerRegistration> service_worker_registration) {
+    const scoped_refptr<ServiceWorkerRegistration>&
+        service_worker_registration) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   // TODO(mvanouwerkerk): UMA logging.
   if (service_worker_status != SERVICE_WORKER_OK) {
     RunDeliverCallback(deliver_message_callback,
                        PUSH_DELIVERY_STATUS_NO_SERVICE_WORKER);
     return;
   }
 
   ServiceWorkerVersion* version = service_worker_registration->active_version();
   DCHECK(version);
@@ skipping 64 matching lines @@
     case SERVICE_WORKER_ERROR_MAX_VALUE:
       NOTREACHED() << "Got unexpected error code: " << service_worker_status
                    << " " << ServiceWorkerStatusToString(service_worker_status);
       delivery_status = PUSH_DELIVERY_STATUS_SERVICE_WORKER_ERROR;
       break;
   }
   RunDeliverCallback(deliver_message_callback, delivery_status);
 }
 
 }  // namespace content