Load data URI images in an async way according to spec

third_party/WebKit/Source/core/html/parser/HTMLSrcsetParser.cpp

 /*
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 337 matching lines @@
     }
     return i;
 }
 
 static unsigned avoidDownloadIfHigherDensityResourceIsInCache(Vector<ImageCandidate*>& imageCandidates, unsigned winner, Document* document)
 {
     if (!document)
         return winner;
     for (unsigned i = imageCandidates.size() - 1; i > winner; --i) {
         KURL url = document->completeURL(stripLeadingAndTrailingHTMLSpaces(imageCandidates[i]->url()));
-        if (memoryCache()->resourceForURL(url, document->fetcher()->getCacheIdentifier()))
+        if (memoryCache()->resourceForURL(url, document->fetcher()->getCacheIdentifier()) || url.protocolIsData())
             return i;
     }
     return winner;
 }
 
 static ImageCandidate pickBestImageCandidate(float deviceScaleFactor, float sourceSize, Vector<ImageCandidate>& imageCandidates, Document* document = nullptr)
 {
     const float defaultDensityValue = 1.0;
     bool ignoreSrc = false;
     if (imageCandidates.isEmpty())
@@ skipping 66 matching lines @@
     Vector<ImageCandidate> imageCandidates;
     imageCandidates.append(srcsetImageCandidate);
 
     if (!srcAttribute.isEmpty())
         imageCandidates.append(ImageCandidate(srcAttribute, 0, srcAttribute.length(), DescriptorParsingResult(), ImageCandidate::SrcOrigin));
 
     return pickBestImageCandidate(deviceScaleFactor, sourceSize, imageCandidates).toString();
 }
 
 }