Set the request mode and the credentials mode of FetchEvent in the service worker correctly.

third_party/WebKit/Source/core/loader/ImageLoader.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 298 matching lines @@
         return;
 
     AtomicString imageSourceURL = m_element->imageSourceURL();
     KURL url = imageSourceToKURL(imageSourceURL);
     ResourcePtr<ImageResource> newImage = 0;
     RefPtrWillBeRawPtr<Element> protectElement(m_element.get());
     if (!url.isNull()) {
         // Unlike raw <img>, we block mixed content inside of <picture> or <img srcset>.
         ResourceLoaderOptions resourceLoaderOptions = ResourceFetcher::defaultResourceOptions();
         ResourceRequest resourceRequest(url);
-        resourceRequest.setFetchCredentialsMode(WebURLRequest::FetchCredentialsModeSameOrigin);
         if (updateBehavior == UpdateForcedReload) {
             resourceRequest.setCachePolicy(ResourceRequestCachePolicy::ReloadBypassingCache);
             resourceRequest.setLoFiState(WebURLRequest::LoFiOff);
             // ImageLoader defers the load of images when in an ImageDocument.
             // Don't defer this load on a forced reload.
             m_loadingImageDocument = false;
         }
 
         if (RuntimeEnabledFeatures::referrerPolicyAttributeEnabled() && referrerPolicy != ReferrerPolicyDefault)
             resourceRequest.setHTTPReferrer(SecurityPolicy::generateReferrer(referrerPolicy, url, document.outgoingReferrer()));
@@ skipping 350 matching lines @@
 
 void ImageLoader::sourceImageChanged()
 {
     for (auto& client : m_clients) {
         ImageLoaderClient* handle = client;
         handle->notifyImageSourceChanged();
     }
 }
 
 } // namespace blink