Enable Media query evaluation in the preload scanner

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 5f55827bd83983311ed58558a502dfe055d1d135..acac128e8a50d03b89fc85b4793f8818b614a8e7 100644
--- a/Source/core/html/parser/HTMLPreloadScanner.cpp
+++ b/Source/core/html/parser/HTMLPreloadScanner.cpp
@@ -31,6 +31,8 @@
 #include "HTMLNames.h"
 #include "InputTypeNames.h"
 #include "RuntimeEnabledFeatures.h"
+#include "core/css/MediaList.h"
+#include "core/css/MediaQueryEvaluator.h"
 #include "core/html/LinkRelAttribute.h"
 #include "core/html/parser/HTMLParserIdioms.h"
 #include "core/html/parser/HTMLSrcsetParser.h"
@@ -90,16 +92,26 @@ static String initiatorFor(const StringImpl* tagImpl)
     return emptyString();
 }
 
+static bool mediaAttributeMatches(const MediaValues* mediaValues, const String& attributeValue)
+{
+    RefPtr<MediaQuerySet> mediaQueries = MediaQuerySet::create(attributeValue);
+    MediaQueryEvaluator mediaQueryEvaluator("screen", mediaValues, false);
+    bool ret = mediaQueryEvaluator.eval(mediaQueries.get());
+    return ret;

[abarth-chromium, 2014/03/24 19:43:31]

I'd skip |ret| and just return the result of the function directly.

+}
+
 class TokenPreloadScanner::StartTagScanner {
 public:
-    StartTagScanner(const StringImpl* tagImpl, float deviceScaleFactor)
+    StartTagScanner(const StringImpl* tagImpl, float deviceScaleFactor, PassRefPtr<MediaValues> mediaValues)
         : m_tagImpl(tagImpl)
         , m_linkIsStyleSheet(false)
+        , m_mediaMatch(true)

[abarth-chromium, 2014/03/24 19:43:31]

We can probably come up with a slightly better name for this variable.  The
trick for boolean member variables is to read the follow sentence aloud:

"if <name-of-class> <name-of-bool-member>, ..."

If that makes sense, then we've got a good name.  Otherwise, there's room for
improvement.  For example,

"if the token preload scanner encountered img@src, ..."

         , m_inputIsImage(false)
         , m_deviceScaleFactor(deviceScaleFactor)
         , m_encounteredImgSrc(false)
         , m_isCORSEnabled(false)
         , m_allowCredentials(DoNotAllowStoredCredentials)
+        , m_mediaValues(mediaValues)
     {
         if (!match(m_tagImpl, imgTag)
             && !match(m_tagImpl, inputTag)
@@ -135,12 +147,12 @@ public:
 
     PassOwnPtr<PreloadRequest> createPreloadRequest(const KURL& predictedBaseURL, const SegmentedString& source)
     {
-        if (!shouldPreload())
+        if (!shouldPreload() || !m_mediaMatch)
             return nullptr;
 
         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);
+        OwnPtr<PreloadRequest> request = PreloadRequest::create(initiatorFor(m_tagImpl), position, m_urlToLoad, predictedBaseURL, resourceType());
         if (isCORSEnabled())
             request->setCrossOriginEnabled(allowStoredCredentials());
         request->setCharset(charset());
@@ -148,6 +160,7 @@ public:
     }
 
 private:
+

[abarth-chromium, 2014/03/24 19:43:31]

This change looks spurious

     template<typename NameType>
     void processAttribute(const NameType& attributeName, const String& attributeValue)
     {
@@ -177,7 +190,7 @@ private:
             else if (match(attributeName, relAttr))
                 m_linkIsStyleSheet = relAttributeIsStyleSheet(attributeValue);
             else if (match(attributeName, mediaAttr))
-                m_mediaAttribute = attributeValue;
+                m_mediaMatch = mediaAttributeMatches(m_mediaValues.get(), attributeValue);
             else if (match(attributeName, crossoriginAttr))
                 setCrossOriginAllowed(attributeValue);
         } else if (match(m_tagImpl, inputTag)) {
@@ -261,19 +274,21 @@ private:
     ImageCandidate m_srcsetImageCandidate;
     String m_charset;
     bool m_linkIsStyleSheet;
-    String m_mediaAttribute;
+    bool m_mediaMatch;
     bool m_inputIsImage;
     float m_deviceScaleFactor;
     bool m_encounteredImgSrc;
     bool m_isCORSEnabled;
     StoredCredentials m_allowCredentials;
+    RefPtr<MediaValues> m_mediaValues;
 };
 
-TokenPreloadScanner::TokenPreloadScanner(const KURL& documentURL, float deviceScaleFactor)
+TokenPreloadScanner::TokenPreloadScanner(const KURL& documentURL, float deviceScaleFactor, PassRefPtr<MediaValues> mediaValues)
     : m_documentURL(documentURL)
     , m_inStyle(false)
     , m_deviceScaleFactor(deviceScaleFactor)
     , m_templateCount(0)
+    , m_mediaValues(mediaValues)
 {
 }
 
@@ -288,6 +303,7 @@ TokenPreloadScannerCheckpoint TokenPreloadScanner::createCheckpoint()
     return checkpoint;
 }
 
+

[abarth-chromium, 2014/03/24 19:43:31]

ditto

 void TokenPreloadScanner::rewindTo(TokenPreloadScannerCheckpoint checkpointIndex)
 {
     ASSERT(checkpointIndex < m_checkpoints.size()); // If this ASSERT fires, checkpointIndex is invalid.
@@ -353,7 +369,7 @@ void TokenPreloadScanner::scanCommon(const Token& token, const SegmentedString&
             return;
         }
 
-        StartTagScanner scanner(tagImpl, m_deviceScaleFactor);
+        StartTagScanner scanner(tagImpl, m_deviceScaleFactor, m_mediaValues);
         scanner.processAttributes(token.attributes());
         OwnPtr<PreloadRequest> request = scanner.createPreloadRequest(m_predictedBaseElementURL, source);
         if (request)
@@ -374,8 +390,8 @@ void TokenPreloadScanner::updatePredictedBaseURL(const Token& token)
         m_predictedBaseElementURL = KURL(m_documentURL, stripLeadingAndTrailingHTMLSpaces(hrefAttribute->value)).copy();
 }
 
-HTMLPreloadScanner::HTMLPreloadScanner(const HTMLParserOptions& options, const KURL& documentURL, float deviceScaleFactor)
-    : m_scanner(documentURL, deviceScaleFactor)
+HTMLPreloadScanner::HTMLPreloadScanner(const HTMLParserOptions& options, const KURL& documentURL, float deviceScaleFactor, PassRefPtr<MediaValues> mediaValues)
+    : m_scanner(documentURL, deviceScaleFactor, mediaValues)
     , m_tokenizer(HTMLTokenizer::create(options))
 {
 }