ServiceWorker: Implement attributes of ExtendableMessageEvent

third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerMessageEvent.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/serviceworkers/ServiceWorkerMessageEvent.h"
 
 namespace blink {
 
 ServiceWorkerMessageEvent::ServiceWorkerMessageEvent()
 {
@@ skipping 27 matching lines @@
     if (m_serializedData)
         m_serializedData->registerMemoryAllocatedWithCurrentScriptContext();
 }
 
 ServiceWorkerMessageEvent::~ServiceWorkerMessageEvent()
 {
 }
 
 MessagePortArray ServiceWorkerMessageEvent::ports(bool& isNull) const
 {
+    // TODO(bashi): Currently we return a copied array because the binding
+    // layer could modify the content of the array while executing JS callbacks.
+    // Avoid copying once we can make sure that the binding layer won't
+    // modify the content.
     if (m_ports) {
         isNull = false;
         return *m_ports;
     }
     isNull = true;
     return MessagePortArray();
 }
 
 MessagePortArray ServiceWorkerMessageEvent::ports() const
 {
@@ skipping 16 matching lines @@
 
 DEFINE_TRACE(ServiceWorkerMessageEvent)
 {
     visitor->trace(m_sourceAsServiceWorker);
     visitor->trace(m_sourceAsMessagePort);
     visitor->trace(m_ports);
     Event::trace(visitor);
 }
 
 } // namespace blink