Use srcset's resource pixel density to determine intrinsic size

Source/core/html/parser/HTMLSrcsetParser.cpp

Index: Source/core/html/parser/HTMLSrcsetParser.cpp
diff --git a/Source/core/html/parser/HTMLSrcsetParser.cpp b/Source/core/html/parser/HTMLSrcsetParser.cpp
index 40c95a19643c7000afcc631bcf41f13bd126effb..e65e3f54baa0aef731bd75c2169279e416250e42 100644
--- a/Source/core/html/parser/HTMLSrcsetParser.cpp
+++ b/Source/core/html/parser/HTMLSrcsetParser.cpp
@@ -154,7 +154,7 @@ ImageCandidate bestFitSourceForSrcsetAttribute(float deviceScaleFactor, const St
     return pickBestImageCandidate(deviceScaleFactor, imageCandidates);
 }
 
-String bestFitSourceForImageAttributes(float deviceScaleFactor, const String& srcAttribute, const String& srcsetAttribute)
+String bestFitSourceForImageAttributes(float deviceScaleFactor, const String& srcAttribute, const String& srcsetAttribute, float& intrinsicSizeFactor)
 {
     if (srcsetAttribute.isNull())
         return srcAttribute;
@@ -166,7 +166,10 @@ String bestFitSourceForImageAttributes(float deviceScaleFactor, const String& sr
     if (!srcAttribute.isEmpty())
         imageCandidates.append(ImageCandidate(srcAttribute, 0, srcAttribute.length(), 1.0));
 
-    return pickBestImageCandidate(deviceScaleFactor, imageCandidates).toString();
+    ImageCandidate candidate = pickBestImageCandidate(deviceScaleFactor, imageCandidates);
+    intrinsicSizeFactor = 1 / candidate.scaleFactor();

[pdr., 2013/10/11 05:17:33]

Do we need to check that scaleFactor is non-zero here?

The spec requires this but it doesn't seem to be enforced in HTMLSrcsetParser.

[Yoav Weiss, 2013/10/11 07:22:32]

Yes, we should. Will fix. 

+
+    return candidate.toString();
 }
 
 String bestFitSourceForImageAttributes(float deviceScaleFactor, const String& srcAttribute, ImageCandidate& srcsetImageCandidate)