service worker: Add NavigationPreload runtime flag and skeleton interface

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"
+
+namespace blink {
+
+ScriptPromise NavigationPreloadManager::enable(ScriptState*) {
+  NOTIMPLEMENTED();
+  return ScriptPromise();
+}
+
+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() {}
+
+}  // namespace blink