Resolve FetchEvent.preloadResponse with undefined when Navigation Preload is disabled.

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

 // 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.
 
 #include "modules/serviceworkers/FetchEvent.h"
 
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/ToV8.h"
 #include "bindings/core/v8/V8HiddenValue.h"
 #include "modules/fetch/BytesConsumerForDataConsumerHandle.h"
@@ skipping 58 matching lines @@
                        const FetchEventInit& initializer,
                        RespondWithObserver* respondWithObserver,
                        WaitUntilObserver* waitUntilObserver,
                        bool navigationPreloadSent)
     : ExtendableEvent(type, initializer, waitUntilObserver),
       m_observer(respondWithObserver),
       m_preloadResponseProperty(new PreloadResponseProperty(
           scriptState->getExecutionContext(),
           this,
           PreloadResponseProperty::PreloadResponse)) {
-  if (!navigationPreloadSent) {
-    // TODO(horo): This behavior is still under the spec discussion.
-    // https://github.com/w3c/ServiceWorker/issues/920#issuecomment-255874864
-    m_preloadResponseProperty->resolve(nullptr);
-  }
+  if (!navigationPreloadSent)
+    m_preloadResponseProperty->resolveWithUndefined();
 
   m_clientId = initializer.clientId();
   m_isReload = initializer.isReload();
   if (initializer.hasRequest()) {
     ScriptState::Scope scope(scriptState);
     m_request = initializer.request();
     v8::Local<v8::Value> request = ToV8(m_request, scriptState);
     v8::Local<v8::Value> event = ToV8(this, scriptState);
     if (event.IsEmpty()) {
       // |toV8| can return an empty handle when the worker is terminating.
@@ skipping 54 matching lines @@
 }
 
 DEFINE_TRACE(FetchEvent) {
   visitor->trace(m_observer);
   visitor->trace(m_request);
   visitor->trace(m_preloadResponseProperty);
   ExtendableEvent::trace(visitor);
 }
 
 }  // namespace blink