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

content/browser/notifications/notification_event_dispatcher_impl.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/notifications/notification_event_dispatcher_impl.h"
 
 #include "base/callback.h"
 #include "build/build_config.h"
 #include "content/browser/notifications/platform_notification_context_impl.h"
 #include "content/browser/service_worker/service_worker_context_wrapper.h"
@@ skipping 76 matching lines @@
 
 // Dispatches the given notification action event on
 // |service_worker_registration| if the registration was available. Must be
 // called on the IO thread.
 void DispatchNotificationEventOnRegistration(
     const NotificationDatabaseData& notification_database_data,
     const scoped_refptr<PlatformNotificationContext>& notification_context,
     const NotificationOperationCallback& dispatch_event_action,
     const NotificationDispatchCompleteCallback& dispatch_error_callback,
     ServiceWorkerStatusCode service_worker_status,
-    scoped_refptr<ServiceWorkerRegistration> service_worker_registration) {
+    const scoped_refptr<ServiceWorkerRegistration>&
+        service_worker_registration) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 #if defined(OS_ANDROID)
   // This LOG(INFO) deliberately exists to help track down the cause of
   // https://crbug.com/534537, where notifications sometimes do not react to
   // the user clicking on them. It should be removed once that's fixed.
   LOG(INFO) << "Trying to dispatch notification for SW with status: "
             << service_worker_status;
 #endif
   if (service_worker_status == SERVICE_WORKER_OK) {
     DCHECK(service_worker_registration->active_version());
@@ skipping 266 matching lines @@
     const GURL& origin,
     bool by_user,
     const NotificationDispatchCompleteCallback& dispatch_complete_callback) {
   DispatchNotificationEvent(browser_context, persistent_notification_id, origin,
                             base::Bind(&DoDispatchNotificationCloseEvent,
                                        by_user, dispatch_complete_callback),
                             dispatch_complete_callback);
 }
 
 }  // namespace content