Service Worker: FetchEvent.preventDefault() results in a network error

Source/modules/serviceworkers/RespondWithObserver.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 RespondWithObserver_h
 #define RespondWithObserver_h
 
 #include "core/dom/ContextLifecycleObserver.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/WebURLRequest.h"
 
 namespace blink {
 
 class ExceptionState;
 class ExecutionContext;
 class ScriptState;
 class ScriptValue;
 
 // This class observes the service worker's handling of a FetchEvent and
 // notifies the client.
 class RespondWithObserver final : public GarbageCollectedFinalized<RespondWithObserver>, public ContextLifecycleObserver {
 public:
     static RespondWithObserver* create(ExecutionContext*, int eventID, WebURLRequest::FetchRequestMode, WebURLRequest::FrameType);
 
     virtual void contextDestroyed() override;
 
-    void didDispatchEvent();
+    void didDispatchEvent(bool defaultPrevented);
 
     // Observes the promise and delays calling didHandleFetchEvent() until the
     // given promise is resolved or rejected.
     void respondWith(ScriptState*, const ScriptValue&, ExceptionState&);
 
     void responseWasRejected();
     void responseWasFulfilled(const ScriptValue&);
 
     void trace(Visitor*) { }
 
 private:
     class ThenFunction;
 
     RespondWithObserver(ExecutionContext*, int eventID, WebURLRequest::FetchRequestMode, WebURLRequest::FrameType);
 
     int m_eventID;
     WebURLRequest::FetchRequestMode m_requestMode;
     WebURLRequest::FrameType m_frameType;
 
     enum State { Initial, Pending, Done };
     State m_state;
 };
 
 } // namespace blink
 
 #endif // RespondWithObserver_h