[Presentation API] Added the DefaultPresentationStart event and parsing of the default presentation…

Source/modules/presentation/DefaultPresentationStartEventInit.idl

Index: Source/modules/presentation/DefaultPresentationStartEventInit.idl
diff --git a/Source/modules/presentation/DefaultPresentationStartEventInit.idl b/Source/modules/presentation/DefaultPresentationStartEventInit.idl
new file mode 100644
index 0000000000000000000000000000000000000000..82e580c9977872b199e04cd2b6bd52534fa94b99
--- /dev/null
+++ b/Source/modules/presentation/DefaultPresentationStartEventInit.idl
@@ -0,0 +1,12 @@
+// 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.
+
+// This is not part of the spec yet but is considered an essential feature to have.
+// See https://github.com/w3c/presentation-api/issues/26 and the Working Group discussion
+// http://lists.w3.org/Archives/Public/public-webscreens/2014Nov/0007.html
+// Chromium specific discussion might be found at https://code.google.com/p/chromium/issues/detail?id=459001

[mlamouri (slow - plz ping), 2015/03/06 22:43:42]

Hmm, I don't think I would add that. There are two outcomes:
- it's rejected, never added to the spec so you will remove it from Chromium
implementation;
- it's accepted, added to the spec, you will forget to update that comment.

[whywhat, 2015/03/10 13:00:44]

Done.

+
+dictionary DefaultPresentationStartEventInit : EventInit {
+    PresentationSession session;
+};