Ignore src candidates when looking for already in-cache resources

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 338 matching lines @@
 
         currentDensity = imageCandidates[i].density();
         geometricMean = sqrt(currentDensity * nextDensity);
         if (deviceScaleFactor >= geometricMean)
             return next;
         break;
     }
     return i;
 }
 
-static unsigned avoidDownloadIfHigherDensityResourceIsInCache(Vector<ImageCandidate>& imageCandidates, unsigned winner, Document* document)
+static unsigned avoidDownloadIfHigherDensityResourceIsInCache(Vector<ImageCandidate>& imageCandidates, unsigned winner, Document* document, bool ignoreSrc)
 {
     if (!document)
         return winner;
     for (unsigned i = imageCandidates.size() - 1; i > winner; --i) {
+        if (ignoreSrc && imageCandidates[i].srcOrigin())
+            continue;
         KURL url = document->completeURL(stripLeadingAndTrailingHTMLSpaces(imageCandidates[i].url()));
         if (memoryCache()->resourceForURL(url, document->fetcher()->getCacheIdentifier()))
             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())
         return ImageCandidate();
 
     // http://picture.responsiveimages.org/#normalize-source-densities
     for (ImageCandidate& image : imageCandidates) {
         if (image.resourceWidth() > 0) {
             image.setDensity((float)image.resourceWidth() / sourceSize);
             ignoreSrc = true;
         } else if (image.density() < 0) {
             image.setDensity(defaultDensityValue);
         }
     }
 
     std::stable_sort(imageCandidates.begin(), imageCandidates.end(), compareByDensity);
 
     unsigned winner = selectionLogic(imageCandidates, deviceScaleFactor, ignoreSrc);
     ASSERT(winner < imageCandidates.size());
-    winner = avoidDownloadIfHigherDensityResourceIsInCache(imageCandidates, winner, document);
+    winner = avoidDownloadIfHigherDensityResourceIsInCache(imageCandidates, winner, document, ignoreSrc);
 
     float winningDensity = imageCandidates[winner].density();
     // 16. If an entry b in candidates has the same associated ... pixel density as an earlier entry a in candidates,
     // then remove entry b
     while ((winner > 0) && (imageCandidates[winner - 1].density() == winningDensity))
         --winner;
 
     return imageCandidates[winner];
 }
 
@@ skipping 32 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();
 }
 
 }