Add a WebDocument::watchCssSelectors(selectors)

Source/core/dom/Element.cpp

Index: Source/core/dom/Element.cpp
diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
index 0aedfeca43c66160a8b0836989d23c7891ca88c4..680bcf5b53df0e18f19b60a11ebbd05fcac35268 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -43,6 +43,7 @@
 #include "core/css/resolver/StyleResolver.h"
 #include "core/dom/Attr.h"
 #include "core/dom/Attribute.h"
+#include "core/dom/CSSSelectorWatch.h"
 #include "core/dom/ClientRect.h"
 #include "core/dom/ClientRectList.h"
 #include "core/dom/CustomElement.h"
@@ -1337,6 +1338,8 @@ void Element::attach(const AttachContext& context)
 
     NodeRenderingContext(this, context.resolvedStyle).createRendererForElementIfNeeded();
 
+    updateCallbackSelectors(Add);
+
     createPseudoElementIfNeeded(BEFORE);
 
     // When a shadow root exists, it does the work of attaching the children.
@@ -1378,6 +1381,7 @@ void Element::detach(const AttachContext& context)
     WidgetHierarchyUpdatesSuspensionScope suspendWidgetHierarchyUpdates;
     unregisterNamedFlowContentNode();
     cancelFocusAppearanceUpdate();
+    updateCallbackSelectors(Remove);
     if (hasRareData()) {
         ElementRareData* data = elementRareData();
         data->setPseudoElement(BEFORE, 0);
@@ -1461,6 +1465,24 @@ bool Element::recalcStyle(StyleChange change)
     if (hasCustomStyleCallbacks())
         willRecalcStyle(change);
 
+    class SelectorWatchUpdater {
+    public:
+        SelectorWatchUpdater(Element* element)
+            : m_element(element)
+        {
+            m_element->updateCallbackSelectors(Remove);
+        }
+
+        ~SelectorWatchUpdater()
+        {
+            m_element->updateCallbackSelectors(Add);
+        }
+
+    private:
+        Element* const m_element;
+    };
+    SelectorWatchUpdater watchUpdater(this);
+
     // Ref currentStyle in case it would otherwise be deleted when setting the new style in the renderer.
     RefPtr<RenderStyle> currentStyle = renderStyle();
     bool hasParentStyle = static_cast<bool>(parentRenderStyle());
@@ -2446,6 +2468,33 @@ void Element::cancelFocusAppearanceUpdate()
         document()->cancelFocusAppearanceUpdate();
 }
 
+void Element::updateCallbackSelectors(AddOrRemove addOrRemove)
+{
+    if (!renderStyle())
+        return;
+    const Vector<String>& callbackSelectors = renderStyle()->callbackSelectors();
+    if (callbackSelectors.isEmpty())
+        return;
+
+    CSSSelectorWatch* selectorWatch = CSSSelectorWatch::from(document());
+    switch (addOrRemove) {
+    case Add: {
+        ElementRareData* rareData = ensureElementRareData();
+        if (!rareData->renderStyleWatchedSelectorsRepresentedInSelectorWatch()) {
+            selectorWatch->addSelectorMatches(callbackSelectors);
+            rareData->setRenderStyleWatchedSelectorsRepresentedInSelectorWatch(true);
+        }
+        break;
+    }
+    case Remove:
+        if (hasRareData() && elementRareData()->renderStyleWatchedSelectorsRepresentedInSelectorWatch()) {
+            selectorWatch->removeSelectorMatches(callbackSelectors);
+            elementRareData()->setRenderStyleWatchedSelectorsRepresentedInSelectorWatch(false);
+        }
+        break;
+    }
+}
+
 void Element::normalizeAttributes()
 {
     if (!hasAttributes())