Start to implement FetchEvent for ServiceWorker

Source/modules/serviceworkers/FetchEvent.h

+// 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.
+
+#ifndef FetchEvent_h
+#define FetchEvent_h
+
+#include "core/events/Event.h"
+#include "modules/serviceworkers/RespondWithObserver.h"
+
+namespace WebCore {
+
+class ExecutionContext;
+class RespondWithObserver;
+
+// A fetch event is dispatched by the client to a service worker's script
+// context. RespondWithObserver can be used to notify the client about the
+// service worker's response.
+class FetchEvent FINAL : public Event {
+public:
+    static PassRefPtr<FetchEvent> create();
+    static PassRefPtr<FetchEvent> create(PassRefPtr<RespondWithObserver>);
+    virtual ~FetchEvent() { }
+
+    void respondWith(const ScriptValue&);
+
+    virtual const AtomicString& interfaceName() const OVERRIDE;
+
+protected:
+    FetchEvent();
+    explicit FetchEvent(PassRefPtr<RespondWithObserver>);
+
+private:
+    RefPtr<RespondWithObserver> m_observer;
+};
+
+} // namespace WebCore
+
+#endif // FetchEvent_h