[PresentationAPI] on-session-message handler for binary messages (Blink side).

Source/modules/presentation/PresentationSession.idl

 // Copyright 2014 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://w3c.github.io/presentation-api/#interface-presentationsession
 
 enum PresentationSessionState {
     "connected",
     "disconnected"
 };
 
 [
     GarbageCollected,
     RuntimeEnabled=Presentation
 ] interface PresentationSession : EventTarget {
     readonly attribute DOMString? id;
     readonly attribute PresentationSessionState state;
     void close();
     attribute EventHandler onstatechange;
 
     // Communication
-    // TODO(avayvod): attribute BinaryType binaryType;
+    attribute BinaryType binaryType;
     attribute EventHandler onmessage;
     [RaisesException] void send(DOMString message);
     [RaisesException] void send(Blob data);
     [RaisesException] void send(ArrayBuffer data);
     [RaisesException] void send(ArrayBufferView data);
 };