service worker: Add promise boilerplate for NavigationPreload enable/disable

third_party/WebKit/Source/modules/serviceworkers/NavigationPreloadManager.cpp

 // Copyright 2016 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/serviceworkers/NavigationPreloadManager.h"
 
+#include "modules/serviceworkers/NavigationPreloadCallbacks.h"
+#include "modules/serviceworkers/ServiceWorkerRegistration.h"
+
 namespace blink {
 
-ScriptPromise NavigationPreloadManager::enable(ScriptState*) {
-  NOTIMPLEMENTED();
-  return ScriptPromise();
+ScriptPromise NavigationPreloadManager::enable(ScriptState* scriptState) {
+  ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
+  ScriptPromise promise = resolver->promise();
+  m_registration->webRegistration()->enableNavigationPreload(
+      new EnableNavigationPreloadCallbacks(resolver));
+  return promise;
 }
 
 ScriptPromise NavigationPreloadManager::disable(ScriptState*) {
   NOTIMPLEMENTED();
   return ScriptPromise();
 }
 
 ScriptPromise NavigationPreloadManager::setHeaderValue(ScriptState*,
                                                        const String& value) {
   NOTIMPLEMENTED();
   return ScriptPromise();
 }
 
 ScriptPromise NavigationPreloadManager::getState(ScriptState*) {
   NOTIMPLEMENTED();
   return ScriptPromise();
 }
 
-NavigationPreloadManager::NavigationPreloadManager() {}
+NavigationPreloadManager::NavigationPreloadManager(
+    ServiceWorkerRegistration* registration)
+    : m_registration(registration) {}
+
+DEFINE_TRACE(NavigationPreloadManager) {
+  visitor->trace(m_registration);
+}
 
 }  // namespace blink