Implement BackgroundFetchManager.fetch() and struct traits

third_party/WebKit/Source/modules/background_fetch/BackgroundFetchRegistration.cpp

 // Copyright 2017 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 "modules/background_fetch/BackgroundFetchRegistration.h"
 
 #include "modules/background_fetch/BackgroundFetchBridge.h"
 #include "modules/background_fetch/IconDefinition.h"
 #include "modules/serviceworkers/ServiceWorkerRegistration.h"
 
 namespace blink {
 
 BackgroundFetchRegistration::BackgroundFetchRegistration(
-    ServiceWorkerRegistration* registration,
     String tag,
     HeapVector<IconDefinition> icons,
     long long totalDownloadSize,
     String title)
-    : m_registration(registration),
-      m_tag(tag),
+    : m_tag(tag),
       m_icons(icons),
       m_totalDownloadSize(totalDownloadSize),
       m_title(title) {}
 
 BackgroundFetchRegistration::~BackgroundFetchRegistration() = default;
 
+void BackgroundFetchRegistration::setServiceWorkerRegistration(
+    ServiceWorkerRegistration* registration) {
+  m_registration = registration;
+}
+
 String BackgroundFetchRegistration::tag() const {
   return m_tag;
 }
 
 HeapVector<IconDefinition> BackgroundFetchRegistration::icons() const {
   return m_icons;
 }
 
 long long BackgroundFetchRegistration::totalDownloadSize() const {
   return m_totalDownloadSize;
 }
 
 String BackgroundFetchRegistration::title() const {
   return m_title;
 }
 
 void BackgroundFetchRegistration::abort() {
+  DCHECK(m_registration);
   BackgroundFetchBridge::from(m_registration)->abort(m_tag);
 }
 
 DEFINE_TRACE(BackgroundFetchRegistration) {
   visitor->trace(m_registration);
   visitor->trace(m_icons);
 }
 
 }  // namespace blink