ServiceWorker: Implement attributes of ExtendableMessageEvent

third_party/WebKit/Source/modules/serviceworkers/ExtendableMessageEvent.h

 // Copyright 2016 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.
 
 #ifndef ExtendableMessageEvent_h
 #define ExtendableMessageEvent_h
 
 #include "modules/EventModules.h"
 #include "modules/ModulesExport.h"
 #include "modules/serviceworkers/ExtendableEvent.h"
 #include "modules/serviceworkers/ExtendableMessageEventInit.h"
 
 namespace blink {
 
 class MODULES_EXPORT ExtendableMessageEvent final : public ExtendableEvent {
     DEFINE_WRAPPERTYPEINFO();
 
 public:
     static PassRefPtrWillBeRawPtr<ExtendableMessageEvent> create();
     static PassRefPtrWillBeRawPtr<ExtendableMessageEvent> create(const AtomicString& type, const ExtendableMessageEventInit& initializer);
     static PassRefPtrWillBeRawPtr<ExtendableMessageEvent> create(const AtomicString& type, const ExtendableMessageEventInit& initializer, WaitUntilObserver*);
+    static PassRefPtrWillBeRawPtr<ExtendableMessageEvent> create(PassRefPtr<SerializedScriptValue> data, const String& origin, PassOwnPtrWillBeRawPtr<MessagePortArray> ports, WaitUntilObserver*);
+
+    ScriptValue data() const { return m_data; }
+    SerializedScriptValue* serializedData() const { return m_serializedData.get(); }
+    const String& origin() const { return m_origin; }
+    const String& lastEventId() const { return m_lastEventId; }
+    MessagePortArray ports(bool& isNull) const;
+    MessagePortArray ports() const;
+    void source(ClientOrServiceWorkerOrMessagePort& result) const;
 
     const AtomicString& interfaceName() const override;
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     ExtendableMessageEvent();
     ExtendableMessageEvent(const AtomicString& type, const ExtendableMessageEventInit& initializer);
     ExtendableMessageEvent(const AtomicString& type, const ExtendableMessageEventInit& initializer, WaitUntilObserver*);
+    ExtendableMessageEvent(PassRefPtr<SerializedScriptValue> data, const String& origin, PassOwnPtrWillBeRawPtr<MessagePortArray> ports, WaitUntilObserver*);
+
+    ScriptValue m_data;

[bashi, 2016/02/10 00:38:55]

We cannot hold a ScriptValue in a DOM impl class. It adds a strong reference
from Blink to V8, resulting a memory leak. See
https://code.google.com/p/chromium/issues/detail?id=501866 and
https://code.google.com/p/chromium/issues/detail?id=529941 for details.

A quick fix would be a custom constructor which stores |data| as a hidden value
of the wrapper object like https://codereview.chromium.org/1383543004/

I do feel that this is a design bug in the binding layer (sorry about that).
haraken-san was trying to solve this by trace wrapper proposal[1] and the V8
team took over the proposal. I guess that they will start working on it once
Oilpan is stabilized.

[1]
https://docs.google.com/document/d/1gu7NwxuQ9fLWRRBjbH1MGKr7RZEx9ESRCZ3P4KwvP...

[nhiroki, 2016/02/10 08:08:57]

Done.

+    RefPtr<SerializedScriptValue> m_serializedData;
+    String m_origin;
+    String m_lastEventId;
+    Member<ServiceWorkerClient> m_sourceAsClient;
+    Member<ServiceWorker> m_sourceAsServiceWorker;
+    Member<MessagePort> m_sourceAsMessagePort;
+    OwnPtrWillBeMember<MessagePortArray> m_ports;
 };
 
 } // namespace blink
 
 #endif // ExtendableMessageEvent_h