Have preloader handle crossorigin resources better.

Source/core/html/parser/HTMLPreloadScanner.cpp

Index: Source/core/html/parser/HTMLPreloadScanner.cpp
diff --git a/Source/core/html/parser/HTMLPreloadScanner.cpp b/Source/core/html/parser/HTMLPreloadScanner.cpp
index 895d6a0d96d304c5990f0b09841b87b372392d43..b925f1b81ec4afcdbd7d484a27fa7e7cf0d96c76 100644
--- a/Source/core/html/parser/HTMLPreloadScanner.cpp
+++ b/Source/core/html/parser/HTMLPreloadScanner.cpp
@@ -98,6 +98,8 @@ public:
         , m_inputIsImage(false)
         , m_deviceScaleFactor(deviceScaleFactor)
         , m_encounteredImgSrc(false)
+        , m_isCORSEnabled(false)
+        , m_allowCredentials(DoNotAllowStoredCredentials)
     {
         if (!match(m_tagImpl, imgTag)
             && !match(m_tagImpl, inputTag)
@@ -139,7 +141,8 @@ public:
         TRACE_EVENT_INSTANT1("net", "PreloadRequest", "url", m_urlToLoad.ascii());
         TextPosition position = TextPosition(source.currentLine(), source.currentColumn());
         OwnPtr<PreloadRequest> request = PreloadRequest::create(initiatorFor(m_tagImpl), position, m_urlToLoad, predictedBaseURL, resourceType(), m_mediaAttribute);
-        request->setCrossOriginModeAllowsCookies(crossOriginModeAllowsCookies());
+        if (isCORSEnabled())
+            request->setCrossOriginEnabled(allowCredentials());
         request->setCharset(charset());
         return request.release();
     }
@@ -154,14 +157,14 @@ private:
         if (match(m_tagImpl, scriptTag)) {
             if (match(attributeName, srcAttr))
                 setUrlToLoad(attributeValue, DisallowURLReplacement);
-            else if (match(attributeName, crossoriginAttr) && !attributeValue.isNull())
-                m_crossOriginMode = stripLeadingAndTrailingHTMLSpaces(attributeValue);
+            else if (match(attributeName, crossoriginAttr))
+                setCrossOriginAllowed(attributeValue);
         } else if (match(m_tagImpl, imgTag)) {
             if (match(attributeName, srcAttr) && !m_encounteredImgSrc) {
                 m_encounteredImgSrc = true;
                 setUrlToLoad(bestFitSourceForImageAttributes(m_deviceScaleFactor, attributeValue, m_srcsetImageCandidate), AllowURLReplacement);
-            } else if (match(attributeName, crossoriginAttr) && !attributeValue.isNull()) {
-                m_crossOriginMode = stripLeadingAndTrailingHTMLSpaces(attributeValue);
+            } else if (match(attributeName, crossoriginAttr)) {
+                setCrossOriginAllowed(attributeValue);
             } else if (RuntimeEnabledFeatures::srcsetEnabled()
                 && match(attributeName, srcsetAttr)
                 && m_srcsetImageCandidate.isEmpty()) {
@@ -221,7 +224,7 @@ private:
         return Resource::Raw;
     }
 
-    bool shouldPreload()
+    bool shouldPreload() const
     {
         if (m_urlToLoad.isEmpty())
             return false;
@@ -232,21 +235,36 @@ private:
         return true;
     }
 
-    bool crossOriginModeAllowsCookies()
+    bool isCORSEnabled() const
     {
-        return m_crossOriginMode.isNull() || equalIgnoringCase(m_crossOriginMode, "use-credentials");
+        return m_isCORSEnabled;
+    }
+
+    StoredCredentials allowCredentials() const
+    {
+        return m_allowCredentials;
+    }
+
+    void setCrossOriginAllowed(const String& corsSetting)
+    {
+        m_isCORSEnabled = true;
+        if (!corsSetting.isNull() && equalIgnoringCase(stripLeadingAndTrailingHTMLSpaces(corsSetting), "use-credentials"))
+            m_allowCredentials = AllowStoredCredentials;
+        else
+            m_allowCredentials = DoNotAllowStoredCredentials;
     }
 
     const StringImpl* m_tagImpl;
     String m_urlToLoad;
     ImageCandidate m_srcsetImageCandidate;
     String m_charset;
-    String m_crossOriginMode;
     bool m_linkIsStyleSheet;
     String m_mediaAttribute;
     bool m_inputIsImage;
     float m_deviceScaleFactor;
     bool m_encounteredImgSrc;
+    bool m_isCORSEnabled;
+    StoredCredentials m_allowCredentials;
 };
 
 TokenPreloadScanner::TokenPreloadScanner(const KURL& documentURL, float deviceScaleFactor)