Current work-in-progress crbug.com/567021

third_party/WebKit/Source/core/dom/ShadowTreeStyleSheetCollection.cpp

Index: third_party/WebKit/Source/core/dom/ShadowTreeStyleSheetCollection.cpp
diff --git a/third_party/WebKit/Source/core/dom/ShadowTreeStyleSheetCollection.cpp b/third_party/WebKit/Source/core/dom/ShadowTreeStyleSheetCollection.cpp
index 31aabc718b704256c7345ed3e26bcc5624004a43..610460730c944a565d82a1502da69bb262409045 100644
--- a/third_party/WebKit/Source/core/dom/ShadowTreeStyleSheetCollection.cpp
+++ b/third_party/WebKit/Source/core/dom/ShadowTreeStyleSheetCollection.cpp
@@ -28,6 +28,7 @@
 
 #include "core/HTMLNames.h"
 #include "core/css/CSSStyleSheet.h"
+#include "core/css/StyleSheetContents.h"
 #include "core/css/resolver/StyleResolver.h"
 #include "core/dom/Element.h"
 #include "core/dom/StyleChangeReason.h"
@@ -45,7 +46,7 @@ ShadowTreeStyleSheetCollection::ShadowTreeStyleSheetCollection(ShadowRoot& shado
 {
 }
 
-void ShadowTreeStyleSheetCollection::collectStyleSheets(StyleEngine& engine, StyleSheetCollection& collection)
+void ShadowTreeStyleSheetCollection::collectStyleSheets(StyleSheetCollection& collection)
 {
     for (Node* n : m_styleSheetCandidateNodes) {
         StyleSheetCandidate candidate(*n);
@@ -59,34 +60,18 @@ void ShadowTreeStyleSheetCollection::collectStyleSheets(StyleEngine& engine, Sty
             continue;
 
         collection.appendSheetForList(sheet);
-        if (candidate.canBeActivated(nullAtom))
-            collection.appendActiveStyleSheet(toCSSStyleSheet(sheet));
+        if (candidate.canBeActivated(nullAtom)) {
+            CSSStyleSheet* cssSheet = toCSSStyleSheet(sheet);
+            collection.appendActiveStyleSheet(std::make_pair(cssSheet, &document().styleEngine().ensureRuleSetForSheet(*cssSheet)));
+        }
     }
 }
 
-void ShadowTreeStyleSheetCollection::updateActiveStyleSheets(StyleEngine& engine, StyleResolverUpdateMode updateMode)
+void ShadowTreeStyleSheetCollection::updateActiveStyleSheets()
 {
     StyleSheetCollection collection;
-    collectStyleSheets(engine, collection);
-
-    StyleSheetChange change;
-    analyzeStyleSheetChange(updateMode, collection, change);
-
-    if (StyleResolver* styleResolver = engine.resolver()) {
-        if (change.styleResolverUpdateType != Additive) {
-            // We should not destroy StyleResolver when we find any stylesheet update in a shadow tree.
-            // In this case, we will reset rulesets created from style elements in the shadow tree.
-            styleResolver->resetAuthorStyle(treeScope());
-            styleResolver->removePendingAuthorStyleSheets(m_activeAuthorStyleSheets);
-            styleResolver->lazyAppendAuthorStyleSheets(0, collection.activeAuthorStyleSheets());
-        } else {
-            styleResolver->lazyAppendAuthorStyleSheets(m_activeAuthorStyleSheets.size(), collection.activeAuthorStyleSheets());
-        }
-    }
-    if (change.requiresFullStyleRecalc)
-        toShadowRoot(treeScope().rootNode()).host().setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::ActiveStylesheetsUpdate));
-
-    collection.swap(*this);
+    collectStyleSheets(collection);
+    applyActiveStyleSheetChanges(collection);
 }
 
 } // namespace blink