Track scroll event handlers in nested documents

Source/core/dom/EventHandlerRegistry.cpp

Index: Source/core/dom/EventHandlerRegistry.cpp
diff --git a/Source/core/dom/EventHandlerRegistry.cpp b/Source/core/dom/EventHandlerRegistry.cpp
index b72b465ffaadc0a31187c14559227570e38b81e7..fc2e138af1b23b525d30d21d6f46c631affb1835 100644
--- a/Source/core/dom/EventHandlerRegistry.cpp
+++ b/Source/core/dom/EventHandlerRegistry.cpp
@@ -25,8 +25,15 @@ EventHandlerRegistry::HandlerState::~HandlerState()
 {
 }
 
+EventHandlerRegistry* EventHandlerRegistry::create(Document& document)
+{
+    EventHandlerRegistry* registry = new EventHandlerRegistry(document);
+    registry->suspendIfNeeded();
+    return registry;
+}
+
 EventHandlerRegistry::EventHandlerRegistry(Document& document)
-    : m_document(document)
+    : ActiveDOMObject(&document)
 {
 }
 
@@ -39,11 +46,16 @@ const char* EventHandlerRegistry::supplementName()
     return "EventHandlerRegistry";
 }
 
+Document* EventHandlerRegistry::document() const
+{
+    return static_cast<Document*>(executionContext());
+}
+
 EventHandlerRegistry* EventHandlerRegistry::from(Document& document)
 {
     EventHandlerRegistry* registry = static_cast<EventHandlerRegistry*>(DocumentSupplement::from(document, supplementName()));
     if (!registry) {
-        registry = new EventHandlerRegistry(document);
+        registry = create(document);
         DocumentSupplement::provideTo(document, supplementName(), adoptPtr(registry));
     }
     return registry;
@@ -75,8 +87,12 @@ bool EventHandlerRegistry::updateEventHandlerTargets(ChangeOperation op, EventHa
     EventTargetSet* targets = m_eventHandlers[handlerClass].targets.get();
     if (op == Add) {
 #if ASSERT_ENABLED
-        if (Node* node = target->toNode())
-            ASSERT(&node->document() == &m_document);
+        if (Node* node = target->toNode()) {
+            // The node should either be in the document, or be the Document node of a child
+            // of the document.
+            ASSERT(&node->document() == document()
+                || (node->isDocumentNode() && toDocument(node)->parentDocument() == document()));
+        }
 #endif // ASSERT_ENABLED
 
         if (!targets) {
@@ -86,6 +102,11 @@ bool EventHandlerRegistry::updateEventHandlerTargets(ChangeOperation op, EventHa
 
         if (!targets->add(target).isNewEntry) {
             // Just incremented refcount, no real change.
+#if ASSERT_ENABLED
+            // If this is a child document node, then the count should never go above 1.
+            if (Node* node = target->toNode())
+                ASSERT(!node->isDocumentNode() || &node->document() == document());
+#endif // ASSERT_ENABLED
             return false;
         }
     } else {
@@ -113,19 +134,27 @@ bool EventHandlerRegistry::updateEventHandlerTargets(ChangeOperation op, EventHa
 void EventHandlerRegistry::updateEventHandlerInternal(ChangeOperation op, EventHandlerClass handlerClass, EventTarget* target)
 {
     // After the document has stopped, all updates become no-ops.
-    if (!m_document.isActive()) {
+    if (!document()->isActive())
         return;
-    }
 
-    bool hadHandlers = hasEventHandlers(handlerClass);
-    updateEventHandlerTargets(op, handlerClass, target);
-    bool hasHandlers = hasEventHandlers(handlerClass);
+    // Notify our parent registry if we added the first or removed the last handler.
+    for (Document* document = this->document(); document; document = document->parentDocument()) {
+        EventHandlerRegistry* registry = EventHandlerRegistry::from(*document);
+
+        bool hadHandlers = registry->hasEventHandlers(handlerClass);
+        registry->updateEventHandlerTargets(op, handlerClass, target);
+        bool hasHandlers = registry->hasEventHandlers(handlerClass);
 
-    // Notify the parent document's registry if we added the first or removed
-    // the last handler.
-    if (hadHandlers != hasHandlers && !m_document.parentDocument()) {
-        // This is the root registry; notify clients accordingly.
-        notifyHasHandlersChanged(handlerClass, hasHandlers);
+        if (hadHandlers == hasHandlers) {
+            break;
+        }
+        if (!document->parentDocument()) {
+            // This is the root registry; notify clients accordingly.
+            registry->notifyHasHandlersChanged(handlerClass, hasHandlers);
+        } else {
+            // Report change to parent with our Document as the target.
+            target = document;

[abarth-chromium, 2014/04/23 17:25:54]

I see, I missed this line.

+        }
     }
 }
 
@@ -185,7 +214,7 @@ void EventHandlerRegistry::didRemoveAllEventHandlers(EventTarget& target)
 
 void EventHandlerRegistry::notifyHasHandlersChanged(EventHandlerClass handlerClass, bool hasActiveHandlers)
 {
-    Page* page = m_document.page();
+    Page* page = document()->page();
     ScrollingCoordinator* scrollingCoordinator = page ? page->scrollingCoordinator() : 0;
 
     switch (handlerClass) {
@@ -199,4 +228,13 @@ void EventHandlerRegistry::notifyHasHandlersChanged(EventHandlerClass handlerCla
     }
 }
 
+void EventHandlerRegistry::stop()
+{
+    Document* parentDocument = document()->parentDocument();
+    if (!parentDocument)
+        return;
+    EventHandlerRegistry* parentRegistry = EventHandlerRegistry::from(*parentDocument);
+    parentRegistry->didRemoveAllEventHandlers(*document());
+}
+
 } // namespace WebCore