Add stub for assigning media session to media elements

Source/modules/mediasession/HTMLMediaElementMediaSession.idl

Index: Source/modules/mediasession/HTMLMediaElementMediaSession.idl
diff --git a/Source/modules/mediasession/HTMLMediaElementMediaSession.idl b/Source/modules/mediasession/HTMLMediaElementMediaSession.idl
new file mode 100644
index 0000000000000000000000000000000000000000..05eac41825a62e5512555ce444fa57c258fd406f
--- /dev/null
+++ b/Source/modules/mediasession/HTMLMediaElementMediaSession.idl
@@ -0,0 +1,7 @@
+// 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.
+
+partial interface HTMLMediaElement {

[mlamouri (slow - plz ping), 2015/07/02 09:59:04]

nit: add a link to the spec (ie.
https://mediasession.spec.whatwg.org/#extensions-to-the-htmlmediaelement-inte...)

[davve, 2015/07/02 12:15:44]

Good catch. (Funny that I almost managed to sneak that past philipj. ;)

+    [RuntimeEnabled=MediaSession] attribute MediaSession? session;
+};