Simplify WorkerGlobalScope::m_eventListeners.

third_party/WebKit/Source/core/workers/WorkerGlobalScope.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2009, 2011 Google Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 73 matching lines @@
   // Always use UTF-8 in Workers.
   return KURL(m_url, url);
 }
 
 void WorkerGlobalScope::dispose() {
   DCHECK(thread()->isCurrentThread());
 
   // Event listeners would keep DOMWrapperWorld objects alive for too long.
   // Also, they have references to JS objects, which become dangling once Heap
   // is destroyed.
-  for (auto it = m_eventListeners.begin(); it != m_eventListeners.end();) {
-    V8AbstractEventListener* listener = *it;
-    // clearListenerObject() will unregister the listener from
-    // m_eventListeners, and invalidate the iterator, so we have to advance
-    // it first.
-    ++it;
-    listener->clearListenerObject();
+  m_closing = true;
+  HeapHashSet<Member<V8AbstractEventListener>> listeners;
+  listeners.swap(m_eventListeners);
+  while (!listeners.isEmpty()) {
+    for (const auto& listener : listeners)
+      listener->clearListenerObject();
+    listeners.clear();
+    // Pick up any additions made while iterating.
+    listeners.swap(m_eventListeners);
   }
   removeAllEventListeners();
 
   m_scriptController->dispose();
   m_scriptController.clear();
   m_eventQueue->close();
   m_thread = nullptr;
 }
 
 void WorkerGlobalScope::countFeature(UseCounter::Feature feature) {
@@ skipping 21 matching lines @@
     V8AbstractEventListener* eventListener) {
   // TODO(sof): remove once crbug.com/677654 has been diagnosed.
   CHECK(&ThreadState::fromObject(this)->heap() == &ThreadState::fromObject(eventListener)->heap());
   bool newEntry = m_eventListeners.add(eventListener).isNewEntry;
   CHECK(newEntry);
 }
 
 void WorkerGlobalScope::deregisterEventListener(
     V8AbstractEventListener* eventListener) {
   auto it = m_eventListeners.find(eventListener);
-  CHECK(it != m_eventListeners.end());
+  CHECK(it != m_eventListeners.end() || m_closing);
   m_eventListeners.remove(it);
 }
 
 WorkerLocation* WorkerGlobalScope::location() const {
   if (!m_location)
     m_location = WorkerLocation::create(m_url);
   return m_location.get();
 }
 
 WorkerNavigator* WorkerGlobalScope::navigator() const {
@@ skipping 223 matching lines @@
   visitor->trace(m_timers);
   visitor->trace(m_eventListeners);
   visitor->trace(m_pendingErrorEvents);
   ExecutionContext::trace(visitor);
   EventTargetWithInlineData::trace(visitor);
   SecurityContext::trace(visitor);
   Supplementable<WorkerGlobalScope>::trace(visitor);
 }
 
 }  // namespace blink