Collect active stylesheets and and apply asynchronously.

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

Index: third_party/WebKit/Source/core/dom/DocumentStyleSheetCollection.cpp
diff --git a/third_party/WebKit/Source/core/dom/DocumentStyleSheetCollection.cpp b/third_party/WebKit/Source/core/dom/DocumentStyleSheetCollection.cpp
index fa84e9e997b1793540c568ecd97633d14e90c8eb..1bd5732603c926dac2a58fbee5ecf11a67fefc69 100644
--- a/third_party/WebKit/Source/core/dom/DocumentStyleSheetCollection.cpp
+++ b/third_party/WebKit/Source/core/dom/DocumentStyleSheetCollection.cpp
@@ -45,7 +45,6 @@ DocumentStyleSheetCollection::DocumentStyleSheetCollection(TreeScope& treeScope)
 }
 
 void DocumentStyleSheetCollection::collectStyleSheetsFromCandidates(
-    StyleEngine& engine,
     DocumentStyleSheetCollector& collector) {
   for (Node* n : m_styleSheetCandidateNodes) {
     StyleSheetCandidate candidate(*n);
@@ -70,64 +69,37 @@ void DocumentStyleSheetCollection::collectStyleSheetsFromCandidates(
       continue;
 
     collector.appendSheetForList(sheet);
-    if (candidate.canBeActivated(engine.preferredStylesheetSetName()))
-      collector.appendActiveStyleSheet(toCSSStyleSheet(sheet));
+    if (!candidate.canBeActivated(
+            document().styleEngine().preferredStylesheetSetName()))
+      continue;
+
+    CSSStyleSheet* cssSheet = toCSSStyleSheet(sheet);
+    collector.appendActiveStyleSheet(std::make_pair(
+        cssSheet, document().styleEngine().ruleSetForSheet(*cssSheet)));
   }
 }
 
 void DocumentStyleSheetCollection::collectStyleSheets(
-    StyleEngine& engine,
     DocumentStyleSheetCollector& collector) {
-  DCHECK_EQ(&document().styleEngine(), &engine);
-  collector.appendActiveStyleSheets(engine.injectedAuthorStyleSheets());
-  collectStyleSheetsFromCandidates(engine, collector);
-  if (engine.inspectorStyleSheet())
-    collector.appendActiveStyleSheet(engine.inspectorStyleSheet());
+  for (auto& sheet : document().styleEngine().injectedAuthorStyleSheets()) {
+    collector.appendActiveStyleSheet(std::make_pair(
+        sheet, document().styleEngine().ruleSetForSheet(*sheet)));
+  }
+  collectStyleSheetsFromCandidates(collector);
+  if (CSSStyleSheet* inspectorSheet =
+          document().styleEngine().inspectorStyleSheet()) {
+    collector.appendActiveStyleSheet(std::make_pair(
+        inspectorSheet,
+        document().styleEngine().ruleSetForSheet(*inspectorSheet)));
+  }
 }
 
-void DocumentStyleSheetCollection::updateActiveStyleSheets(

[esprehn, 2016/12/09 01:36:21]

Amazing!

-    StyleEngine& engine,
-    StyleResolverUpdateMode updateMode) {
+void DocumentStyleSheetCollection::updateActiveStyleSheets() {
   // StyleSheetCollection is GarbageCollected<>, allocate it on the heap.
   StyleSheetCollection* collection = StyleSheetCollection::create();
   ActiveDocumentStyleSheetCollector collector(*collection);
-  collectStyleSheets(engine, collector);
-
-  StyleSheetChange change;
-  analyzeStyleSheetChange(updateMode, collection->activeAuthorStyleSheets(),
-                          change);
-
-  if (change.styleResolverUpdateType == Reconstruct) {
-    engine.clearMasterResolver();
-    // TODO(rune@opera.com): The following depends on whether StyleRuleFontFace
-    // was modified or not.  We should only remove modified/removed @font-face
-    // rules, or @font-face rules from removed stylesheets. We currently avoid
-    // clearing the font cache when we have had an analyzed update and no
-    // @font-face rules were removed, in which case requiresFullStyleRecalc will
-    // be false.
-    if (change.requiresFullStyleRecalc)
-      engine.clearFontCache();
-  } else if (StyleResolver* styleResolver = engine.resolver()) {
-    if (change.styleResolverUpdateType != Additive) {
-      DCHECK_EQ(change.styleResolverUpdateType, Reset);
-      engine.resetAuthorStyle(treeScope());
-      engine.removeFontFaceRules(change.fontFaceRulesToRemove);
-      styleResolver->removePendingAuthorStyleSheets(m_activeAuthorStyleSheets);
-      styleResolver->lazyAppendAuthorStyleSheets(
-          0, collection->activeAuthorStyleSheets());
-    } else {
-      styleResolver->lazyAppendAuthorStyleSheets(
-          m_activeAuthorStyleSheets.size(),
-          collection->activeAuthorStyleSheets());
-    }
-  }
-  if (change.requiresFullStyleRecalc)
-    document().setNeedsStyleRecalc(
-        SubtreeStyleChange, StyleChangeReasonForTracing::create(
-                                StyleChangeReason::ActiveStylesheetsUpdate));
-
-  collection->swap(*this);
-  collection->dispose();
+  collectStyleSheets(collector);
+  applyActiveStyleSheetChanges(*collection);
 }
 
 void DocumentStyleSheetCollection::collectViewportRules(