Add support for media attribute on link

third_party/WebKit/Source/core/loader/LinkLoader.cpp

Index: third_party/WebKit/Source/core/loader/LinkLoader.cpp
diff --git a/third_party/WebKit/Source/core/loader/LinkLoader.cpp b/third_party/WebKit/Source/core/loader/LinkLoader.cpp
index 6222b9e52dee076954592c3b538f3ecfefde7b0a..3489d87ace9a2aff0afb73b8eed0b885622d31ee 100644
--- a/third_party/WebKit/Source/core/loader/LinkLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/LinkLoader.cpp
@@ -31,6 +31,8 @@
 
 #include "core/loader/LinkLoader.h"
 
+#include "core/css/MediaList.h"
+#include "core/css/MediaQueryEvaluator.h"
 #include "core/dom/Document.h"
 #include "core/fetch/FetchInitiatorTypeNames.h"
 #include "core/fetch/FetchRequest.h"
@@ -40,6 +42,7 @@
 #include "core/frame/UseCounter.h"
 #include "core/html/CrossOriginAttribute.h"
 #include "core/html/LinkRelAttribute.h"
+#include "core/html/parser/HTMLPreloadScanner.h"
 #include "core/inspector/ConsoleMessage.h"
 #include "core/loader/DocumentLoader.h"
 #include "core/loader/LinkHeader.h"
@@ -247,7 +250,7 @@ static bool isSupportedType(Resource::Type resourceType, const String& mimeType)
 }
 
 static Resource* preloadIfNeeded(const LinkRelAttribute& relAttribute, const KURL& href, Document& document, const String& as, const String& mimeType,
-    CrossOriginAttributeValue crossOrigin, LinkCaller caller, bool& errorOccurred)
+    const String& media, CrossOriginAttributeValue crossOrigin, LinkCaller caller, bool& errorOccurred, ViewportDescription* viewportDescription)
 {
     if (!document.loader() || !relAttribute.isLinkPreload())
         return nullptr;
@@ -259,6 +262,17 @@ static Resource* preloadIfNeeded(const LinkRelAttribute& relAttribute, const KUR
         return nullptr;
     }
 
+    if (!media.isEmpty()) {
+        RefPtrWillBeRawPtr<MediaValues> mediaValues = MediaValues::createDynamicIfFrameExists(document.frame());
+        if (viewportDescription)
+            mediaValues->overrideViewportDimensions(viewportDescription->maxWidth.getFloatValue(), viewportDescription->maxHeight.getFloatValue());
+
+        // Preload only if media matches
+        RefPtrWillBeRawPtr<MediaQuerySet> mediaQueries = MediaQuerySet::create(media);
+        MediaQueryEvaluator evaluator(*mediaValues);
+        if (!evaluator.eval(mediaQueries.get()))
+            return nullptr;
+    }
     if (caller == LinkCalledFromHeader)
         UseCounter::count(document, UseCounter::LinkHeaderPreload);
     Resource::Type resourceType;
@@ -287,9 +301,10 @@ static Resource* preloadIfNeeded(const LinkRelAttribute& relAttribute, const KUR
     return document.loader()->startPreload(resourceType, linkRequest);
 }
 
-void LinkLoader::loadLinksFromHeader(const String& headerValue, const KURL& baseURL, Document* document, const NetworkHintsInterface& networkHintsInterface, CanLoadResources canLoadResources)
+void LinkLoader::loadLinksFromHeader(const String& headerValue, const KURL& baseURL, Document* document, const NetworkHintsInterface& networkHintsInterface,
+    CanLoadResources canLoadResources, ViewportDescriptionWrapper* viewportDescriptionWrapper)
 {
-    if (!document)
+    if (!document || headerValue.isEmpty())
         return;
     LinkHeaderSet headerSet(headerValue);
     for (auto& header : headerSet) {
@@ -307,14 +322,17 @@ void LinkLoader::loadLinksFromHeader(const String& headerValue, const KURL& base
         }
         if (canLoadResources != DoNotLoadResources) {
             bool errorOccurred = false;
-            if (RuntimeEnabledFeatures::linkPreloadEnabled())
-                preloadIfNeeded(relAttribute, url, *document, header.as(), header.mimeType(), header.crossOrigin(), LinkCalledFromHeader, errorOccurred);
+            if (RuntimeEnabledFeatures::linkPreloadEnabled()) {
+                ViewportDescription* viewportDescription = (viewportDescriptionWrapper && viewportDescriptionWrapper->set) ? &(viewportDescriptionWrapper->description) : nullptr;
+                preloadIfNeeded(relAttribute, url, *document, header.as(), header.mimeType(), header.media(), header.crossOrigin(), LinkCalledFromHeader, errorOccurred, viewportDescription);
+            }
         }
         // TODO(yoav): Add more supported headers as needed.
     }
 }
 
-bool LinkLoader::loadLink(const LinkRelAttribute& relAttribute, CrossOriginAttributeValue crossOrigin, const String& type, const String& as, const KURL& href, Document& document, const NetworkHintsInterface& networkHintsInterface)
+bool LinkLoader::loadLink(const LinkRelAttribute& relAttribute, CrossOriginAttributeValue crossOrigin, const String& type,
+    const String& as, const String& media, const KURL& href, Document& document, const NetworkHintsInterface& networkHintsInterface)
 {
     // TODO(yoav): Do all links need to load only after they're in document???
 
@@ -326,7 +344,7 @@ bool LinkLoader::loadLink(const LinkRelAttribute& relAttribute, CrossOriginAttri
 
     bool errorOccurred = false;
     if (m_client->shouldLoadLink())
-        createLinkPreloadResourceClient(preloadIfNeeded(relAttribute, href, document, as, type, crossOrigin, LinkCalledFromMarkup, errorOccurred));
+        createLinkPreloadResourceClient(preloadIfNeeded(relAttribute, href, document, as, type, media, crossOrigin, LinkCalledFromMarkup, errorOccurred, nullptr));
     if (errorOccurred)
         m_linkLoadingErrorTimer.startOneShot(0, BLINK_FROM_HERE);