Introduce the Background Fetch module.

third_party/WebKit/Source/modules/background_fetch/BackgroundFetchManager.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/BackgroundFetchManager.h"
+
+#include "bindings/core/v8/ScriptState.h"
+#include "core/dom/DOMException.h"
+#include "modules/serviceworkers/ServiceWorkerRegistration.h"
+
+namespace blink {
+
+BackgroundFetchManager::BackgroundFetchManager(
+    ServiceWorkerRegistration* registration)
+    : m_registration(registration) {
+  DCHECK(registration);
+}
+
+ScriptPromise BackgroundFetchManager::getTags(ScriptState* scriptState) {
+  return ScriptPromise::rejectWithDOMException(
+      scriptState,
+      DOMException::create(NotSupportedError, "Not implemented yet."));
+}
+
+DEFINE_TRACE(BackgroundFetchManager) {
+  visitor->trace(m_registration);
+}
+
+}  // namespace blink