Add <link rel=preconnect> support to the HTMLPreloadScanner

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 ce827eea14930617ef8a4b290dead20664eee27b..d52b6d903ab3a9a0fbff831c75a480855bd58ab4 100644
--- a/Source/core/html/parser/HTMLPreloadScanner.cpp
+++ b/Source/core/html/parser/HTMLPreloadScanner.cpp
@@ -111,6 +111,7 @@ public:
     StartTagScanner(const StringImpl* tagImpl, PassRefPtr<MediaValues> mediaValues)
         : m_tagImpl(tagImpl)
         , m_linkIsStyleSheet(false)
+        , m_linkIsPreconnect(false)
         , m_matchedMediaAttribute(true)
         , m_inputIsImage(false)
         , m_sourceSize(0)
@@ -166,8 +167,21 @@ public:
             setUrlToLoad(sourceURL, AllowURLReplacement);
     }
 
-    PassOwnPtr<PreloadRequest> createPreloadRequest(const KURL& predictedBaseURL, const SegmentedString& source, const ClientHintsPreferences& clientHintsPreferences)
+    void preconnectHost(PreconnecterHost* preconnecter, KURL baseURL)
     {
+        KURL host(baseURL, m_urlToLoad);
+        if (!host.isValid())
+            return;
+        // TODO(yoav): Add a real cross attribute value here once it's no longer a no-op.

[Mike West, 2015/06/02 11:18:33]

I see. Ok, yes, please add this TODO to the test as well so that it's clear that
the current behavior isn't final.

+        preconnecter->preconnect(host, CrossOriginAttributeNotSet);
+    }
+
+    PassOwnPtr<PreloadRequest> createPreloadRequest(const KURL& predictedBaseURL, const SegmentedString& source, const ClientHintsPreferences& clientHintsPreferences, PreconnecterHost* preconnecter)
+    {
+        if (shouldPreconnect()) {
+            preconnectHost(preconnecter, predictedBaseURL);
+            return nullptr;
+        }
         if (!shouldPreload() || !m_matchedMediaAttribute)
             return nullptr;
 
@@ -229,7 +243,7 @@ private:
         if (match(attributeName, hrefAttr))
             setUrlToLoad(attributeValue, DisallowURLReplacement);
         else if (match(attributeName, relAttr))
-            m_linkIsStyleSheet = relAttributeIsStyleSheet(attributeValue);
+            checkRelAttribute(attributeValue, m_linkIsStyleSheet, m_linkIsPreconnect);
         else if (match(attributeName, mediaAttr))
             m_matchedMediaAttribute = mediaAttributeMatches(*m_mediaValues, attributeValue);
         else if (match(attributeName, crossoriginAttr))
@@ -291,10 +305,11 @@ private:
             processVideoAttribute(attributeName, attributeValue);
     }
 
-    static bool relAttributeIsStyleSheet(const String& attributeValue)
+    static void checkRelAttribute(const String& attributeValue, bool& isStyleSheet, bool& isPreconnect)
     {
         LinkRelAttribute rel(attributeValue);
-        return rel.isStyleSheet() && !rel.isAlternate() && rel.iconType() == InvalidIcon && !rel.isDNSPrefetch();
+        isStyleSheet = rel.isStyleSheet() && !rel.isAlternate() && rel.iconType() == InvalidIcon && !rel.isDNSPrefetch();

[Mike West, 2015/06/02 11:18:33]

Is this used anywhere else? I'd rather see it inlined into line 246 rather than
doing the param-passing here.

+        isPreconnect = rel.isPreconnect();
     }
 
     void setUrlToLoad(const String& value, URLReplacement replacement)
@@ -329,6 +344,11 @@ private:
         return Resource::Raw;
     }
 
+    bool shouldPreconnect() const
+    {
+        return (match(m_tagImpl, linkTag) && m_linkIsPreconnect && !m_urlToLoad.isEmpty());

[Mike West, 2015/06/02 11:18:33]

Nit: Drop the outer ().

+    }
+
     bool shouldPreload() const
     {
         if (m_urlToLoad.isEmpty())
@@ -374,6 +394,7 @@ private:
     ImageCandidate m_srcsetImageCandidate;
     String m_charset;
     bool m_linkIsStyleSheet;
+    bool m_linkIsPreconnect;
     bool m_matchedMediaAttribute;
     bool m_inputIsImage;
     String m_imgSrcUrl;
@@ -386,7 +407,7 @@ private:
     RefPtr<MediaValues> m_mediaValues;
 };
 
-TokenPreloadScanner::TokenPreloadScanner(const KURL& documentURL, PassOwnPtr<CachedDocumentParameters> documentParameters)
+TokenPreloadScanner::TokenPreloadScanner(const KURL& documentURL, PassOwnPtr<CachedDocumentParameters> documentParameters, PassOwnPtr<PreconnecterHost> preconnecter)
     : m_documentURL(documentURL)
     , m_inStyle(false)
     , m_inPicture(false)
@@ -394,6 +415,7 @@ TokenPreloadScanner::TokenPreloadScanner(const KURL& documentURL, PassOwnPtr<Cac
     , m_isCSPEnabled(false)
     , m_templateCount(0)
     , m_documentParameters(documentParameters)
+    , m_preconnecter(preconnecter)
 {
     ASSERT(m_documentParameters.get());
     ASSERT(m_documentParameters->mediaValues.get());
@@ -534,7 +556,7 @@ void TokenPreloadScanner::scanCommon(const Token& token, const SegmentedString&
         scanner.processAttributes(token.attributes());
         if (m_inPicture)
             scanner.handlePictureSourceURL(m_pictureSourceURL);
-        OwnPtr<PreloadRequest> request = scanner.createPreloadRequest(m_predictedBaseElementURL, source, m_clientHintsPreferences);
+        OwnPtr<PreloadRequest> request = scanner.createPreloadRequest(m_predictedBaseElementURL, source, m_clientHintsPreferences, m_preconnecter.get());
         if (request)
             requests.append(request.release());
         return;
@@ -555,8 +577,8 @@ void TokenPreloadScanner::updatePredictedBaseURL(const Token& token)
     }
 }
 
-HTMLPreloadScanner::HTMLPreloadScanner(const HTMLParserOptions& options, const KURL& documentURL, PassOwnPtr<CachedDocumentParameters> documentParameters)
-    : m_scanner(documentURL, documentParameters)
+HTMLPreloadScanner::HTMLPreloadScanner(const HTMLParserOptions& options, const KURL& documentURL, PassOwnPtr<CachedDocumentParameters> documentParameters, PassOwnPtr<PreconnecterHost> preconnecter)
+    : m_scanner(documentURL, documentParameters, preconnecter)
     , m_tokenizer(HTMLTokenizer::create(options))
 {
 }