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

Source/modules/serviceworkers/ServiceWorkerMessageEventInit.idl

Index: Source/modules/serviceworkers/ServiceWorkerMessageEventInit.idl
diff --git a/Source/modules/serviceworkers/FetchEventInit.idl b/Source/modules/serviceworkers/ServiceWorkerMessageEventInit.idl
similarity index 50%
copy from Source/modules/serviceworkers/FetchEventInit.idl
copy to Source/modules/serviceworkers/ServiceWorkerMessageEventInit.idl
index d5755ad38803d3bf32e9a8ca0f60204c954cf47b..ee195feaff717c4af5a7ae95a862222f971faa29 100644
--- a/Source/modules/serviceworkers/FetchEventInit.idl
+++ b/Source/modules/serviceworkers/ServiceWorkerMessageEventInit.idl
@@ -2,10 +2,12 @@
 // 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/index.html#fetch-event-interface
+// https://slightlyoff.github.io/ServiceWorker/spec/service_worker/#serviceworkermessage-event-section
 
-dictionary FetchEventInit : ExtendableEventInit {
-  Request request;
-  Client client;
-  boolean isReload = false;    
+dictionary ServiceWorkerMessageEventInit : EventInit {

[haraken, 2015/05/26 00:25:52]

This is a question against the spec, but why doesn't
ServiceWorkerMessageEventInit inherit from MessageEventInit?

Also ServiceWorkerMessageEvent duplicates a lot of code from MessageEvent. I'm
curious why ServiceWorkerMessageEvent is not speced so that it inherits from
MessageEvent.

[jungkees, 2015/05/27 10:51:33]

falken brought me here.

Subclassing MessageEvent interface was the way we tried first, but it ends up
wonfix:
https://www.w3.org/Bugs/Public/show_bug.cgi?id=28199
One of the reasons is the type of source attribute is radically different from
that of the MessageEvent, and extending HTML text has not happened.

Another reason is ExtendableMessageEvent (a friend of ServiceWorkerMessageEvent)
had to extend both ExtendableEvent (for its waitUntil() method in SW context)
and MessageEvent (for its source attribute as mentioned). We couldn't do it with
subclassing MessageEvent and redefine waitUntil() in the subclass apart from the
ExtendableEvent interface. Please see some of the rationale discussed in the
spec issue here:
https://github.com/slightlyoff/ServiceWorker/issues/669#issuecomment-88860069.

+    any data;
+    DOMString origin;
+    DOMString lastEventId;
+    (ServiceWorker or MessagePort)? source;
+    sequence<MessagePort> ports;
 };