ServiceWorker: Introduce ServiceWorkerMessageEvent to replace MessageEvent (3/3).

Source/modules/serviceworkers/ServiceWorkerMessageEvent.idl

+// 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.
+
+// https://slightlyoff.github.io/ServiceWorker/spec/service_worker/#serviceworkermessage-event-section
+
+[
+    CustomConstructor(DOMString type, optional ServiceWorkerMessageEventInit eventInitDict),

[falken, 2015/05/18 03:40:23]

CustomConstructor is listed as "strongly discouraged"
https://www.chromium.org/blink/webidl/blink-idl-extended-attributes#TOC-Custo...

Can you explain why CustomConstructor is needed?

[bashi, 2015/05/20 05:22:16]

I don't see why you need CustomConstructor. This should be:

Constructor(DOMString type, optional ServiceWorkerMessageEventInit
eventInitDict)

Also, you need to add ServiceWorkerMessageEventInit.idl. It will look like
following:

dictionary ServiceWorkerMessageEventInit : EventInit {
    any data;
    DOMString origin;
    DOMString lastEventId;
    (ServiceWorker or MessagePort)? source;
    sequence<MessagePort> ports;
};

In the constructor (i.e. ServiceWorkerMessageEvent::ServiceWorkerMessageEvent())
you need to initialize its members with the eventInitDict passed by the binding
layer. (See FetchEvent::FetchEvent() for instance)

+    Exposed=(Window, Worker),
+    RuntimeEnabled=ServiceWorker,
+] interface ServiceWorkerMessageEvent : Event {
+    [InitializedByEventConstructor] readonly attribute DOMString origin;

[bashi, 2015/05/20 05:22:16]

Please drop [InitializedByEventConstructor]. It is no longer needed.

+    [InitializedByEventConstructor] readonly attribute DOMString lastEventId;
+    [InitializedByEventConstructor, Custom=Getter] readonly attribute any source;

[bashi, 2015/05/20 05:22:16]

I guess you can use (ServiceWorker or MessagePort)? as the type of |source|.

+    [InitializedByEventConstructor, Custom=Getter] readonly attribute any data;

[bashi, 2015/05/20 05:22:16]

Please be careful not to leak V8 objects to different isolated worlds.
Description of the CL https://codereview.chromium.org/1130763006/ might be
helpful to understand why and how.

+    [InitializedByEventConstructor] readonly attribute MessagePort[] ports;
+    [Custom] void initServiceWorkerMessageEvent([Default=Undefined] optional DOMString typeArg,

[bashi, 2015/05/20 05:22:15]

I think we should not implement this. I filed a bug to the spec.
https://github.com/slightlyoff/ServiceWorker/issues/701

+                                   [Default=Undefined] optional boolean canBubbleArg,
+                                   [Default=Undefined] optional boolean cancelableArg,
+                                   [Default=Undefined] optional any dataArg,
+                                   [Default=Undefined] optional DOMString originArg,
+                                   [Default=Undefined] optional DOMString lastEventIdArg,
+                                   [Default=Undefined] optional any sourceArg,
+                                   [Default=Undefined] optional MessagePort[] messagePorts);
+};