DO NOT SUBMIT really old prototype of sprite recognition for image replacement

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

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 154 matching lines @@
 void DocumentLoader::setSubresourceFilter(std::unique_ptr<WebDocumentSubresourceFilter> subresourceFilter)
 {
     m_subresourceFilter = std::move(subresourceFilter);
 }
 
 Resource* DocumentLoader::startPreload(Resource::Type type, FetchRequest& request)
 {
     Resource* resource = nullptr;
     switch (type) {
     case Resource::Image:
-        resource = ImageResource::fetch(request, fetcher());
+        resource = ImageResource::fetch(request, fetcher(),
+            frame() && frame()->settings() && frame()->settings()->fetchImagePlaceholders()
+                ? ImageResource::PlaceholderRequestType::AllowPlaceholder
+                : ImageResource::PlaceholderRequestType::DisallowPlaceholder);
         break;
     case Resource::Script:
         resource = ScriptResource::fetch(request, fetcher());
         break;
     case Resource::CSSStyleSheet:
         resource = CSSStyleSheetResource::fetch(request, fetcher());
         break;
     case Resource::Font:
         resource = FontResource::fetch(request, fetcher());
         break;
@@ skipping 534 matching lines @@
 {
     m_writer = createWriterFor(init, mimeType(), m_writer ? m_writer->encoding() : emptyAtom, true, ForceSynchronousParsing);
     if (!source.isNull())
         m_writer->appendReplacingData(source);
     endWriting(m_writer.get());
 }
 
 DEFINE_WEAK_IDENTIFIER_MAP(DocumentLoader);
 
 } // namespace blink