Extend srcset's syntax to include 'w' descriptors

Source/core/html/parser/HTMLSrcsetParser.h

 /*
  * 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 17 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef HTMLSrcsetParser_h
 #define HTMLSrcsetParser_h
 
 #include "wtf/text/WTFString.h"
 
 namespace WebCore {
 
+struct DescriptorParsingResult {
+    float scaleFactor;
+    int resourceWidth;
+
+    DescriptorParsingResult()
+    {
+        scaleFactor = -1.0;
+        resourceWidth = -1;
+    }
+
+    bool foundDescriptor() const
+    {
+        return (scaleFactor >= 0 || resourceWidth >= 0);
+    }
+};
+
 class ImageCandidate {
 public:
     ImageCandidate()
         : m_scaleFactor(1.0)
     {
     }
 
-    ImageCandidate(const String& source, unsigned start, unsigned length, float scaleFactor)
+    ImageCandidate(const String& source, unsigned start, unsigned length, const DescriptorParsingResult& result)
         : m_string(source.createView(start, length))
-        , m_scaleFactor(scaleFactor)
+        , m_scaleFactor(result.scaleFactor)
+        , m_resourceWidth(result.resourceWidth)
     {
     }
 
     String toString() const
     {
         return String(m_string.toString());
     }
 
     AtomicString toAtomicString() const
     {
         return AtomicString(m_string.toString());
     }
 
-    inline float scaleFactor() const
+    void setScaleFactor(float factor)
+    {
+        m_scaleFactor = factor;
+    }
+
+    float scaleFactor() const
     {
         return m_scaleFactor;
     }
 
+    int resourceWidth() const
+    {
+        return m_resourceWidth;
+    }
+
     inline bool isEmpty() const
     {
         return m_string.isEmpty();
     }
 
 private:
     StringView m_string;
     float m_scaleFactor;
+    int m_resourceWidth;
 };
 
-ImageCandidate bestFitSourceForSrcsetAttribute(float deviceScaleFactor, const String& srcsetAttribute);
+ImageCandidate bestFitSourceForSrcsetAttribute(float deviceScaleFactor, int effectiveSize, const String& srcsetAttribute);
 
-ImageCandidate bestFitSourceForImageAttributes(float deviceScaleFactor, const String& srcAttribute, const String& srcsetAttribute);
+ImageCandidate bestFitSourceForImageAttributes(float deviceScaleFactor, int effectiveSize, const String& srcAttribute, const String& srcsetAttribute);
 
-String bestFitSourceForImageAttributes(float deviceScaleFactor, const String& srcAttribute, ImageCandidate& srcsetImageCandidate);
+String bestFitSourceForImageAttributes(float deviceScaleFactor, int effectiveSize, const String& srcAttribute, ImageCandidate& srcsetImageCandidate);
 
 }
 
 #endif