Current work-in-progress crbug.com/567021

third_party/WebKit/Source/core/css/CSSStyleSheet.cpp

Index: third_party/WebKit/Source/core/css/CSSStyleSheet.cpp
diff --git a/third_party/WebKit/Source/core/css/CSSStyleSheet.cpp b/third_party/WebKit/Source/core/css/CSSStyleSheet.cpp
index bd4773f8e3088ca945b3e988e3a68d266b40e041..0163aff08690f32acfdf91cf317612647b1fc14d 100644
--- a/third_party/WebKit/Source/core/css/CSSStyleSheet.cpp
+++ b/third_party/WebKit/Source/core/css/CSSStyleSheet.cpp
@@ -174,19 +174,18 @@ void CSSStyleSheet::didMutateRules()
     ASSERT(m_contents->isMutable());
     ASSERT(m_contents->clientSize() <= 1);
 
-    didMutate(PartialRuleUpdate);
+    didMutate();
 }
 
-void CSSStyleSheet::didMutate(StyleSheetUpdateType updateType)
+void CSSStyleSheet::didMutate()
 {
     Document* owner = ownerDocument();
     if (!owner)
         return;
-
-    // Need FullStyleUpdate when insertRule or deleteRule,
-    // because StyleSheetCollection::analyzeStyleSheetChange cannot detect partial rule update.
-    StyleResolverUpdateMode updateMode = updateType != PartialRuleUpdate ? AnalyzedStyleUpdate : FullStyleUpdate;
-    owner->styleEngine().setNeedsActiveStyleUpdate(this, updateMode);
+    if (!ownerNode())
+        return;
+    if (ownerNode()->inShadowIncludingDocument())
+        owner->styleEngine().setNeedsActiveStyleUpdate(ownerNode()->treeScope());
 }
 
 void CSSStyleSheet::reattachChildRuleCSSOMWrappers()
@@ -215,6 +214,17 @@ void CSSStyleSheet::setMediaQueries(MediaQuerySet* mediaQueries)
 
 }
 
+bool CSSStyleSheet::matchesMediaQueries(const MediaQueryEvaluator& evaluator)
+{
+    m_viewportDependentMediaQueryResults.clear();
+    m_deviceDependentMediaQueryResults.clear();
+
+    if (!m_mediaQueries)
+        return true;
+
+    return evaluator.eval(m_mediaQueries, &m_viewportDependentMediaQueryResults, &m_deviceDependentMediaQueryResults);
+}
+
 unsigned CSSStyleSheet::length() const
 {
     return m_contents->ruleCount();
@@ -238,7 +248,7 @@ CSSRule* CSSStyleSheet::item(unsigned index)
 
 void CSSStyleSheet::clearOwnerNode()
 {
-    didMutate(EntireStyleSheetUpdate);
+    didMutate();
     if (m_ownerNode)
         m_contents->unregisterClient(this);
     m_ownerNode = nullptr;
@@ -438,6 +448,8 @@ DEFINE_TRACE(CSSStyleSheet)
 {
     visitor->trace(m_contents);
     visitor->trace(m_mediaQueries);
+    visitor->trace(m_viewportDependentMediaQueryResults);
+    visitor->trace(m_deviceDependentMediaQueryResults);
     visitor->trace(m_ownerNode);
     visitor->trace(m_ownerRule);
     visitor->trace(m_mediaCSSOMWrapper);