RTCPeerConnection: match createDataChannel signature in spec

third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.idl

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 98 matching lines @@
     [CallWith=ScriptState, LegacyInterfaceTypeChecking] Promise<void> getStats(RTCStatsCallback successCallback, optional MediaStreamTrack? selector);
     // TODO(hbos): The spec has an optional |selector| argument that is not
     // supported yet. There is a discussion about what to do with it (clarify
     // spec, remove it or change it?): https://github.com/w3c/webrtc-stats/issues/116
     [CallWith=ScriptState] Promise<RTCStatsReport> getStats();
 
     // https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-getreceivers
     sequence<RTCRtpReceiver> getReceivers();
 
     // https://w3c.github.io/webrtc-pc/#peer-to-peer-data-api
-    // TODO(guidou): The label argument should have [TreatNullAs=EmptyString]
-    // and be non-nullable.
-    [CallWith=ScriptState, RaisesException] RTCDataChannel createDataChannel(DOMString? label, optional Dictionary options);
+    [CallWith=ScriptState, RaisesException] RTCDataChannel createDataChannel(USVString label, optional RTCDataChannelInit dataChannelDict);
     attribute EventHandler ondatachannel;
 
     // Certificate management
     // https://w3c.github.io/webrtc-pc/#sec.cert-mgmt
     [RaisesException, CallWith=ScriptState] static Promise<RTCCertificate> generateCertificate(AlgorithmIdentifier keygenAlgorithm);
 
     // Non-standard or removed from the spec:
     [Measure] sequence<MediaStream> getLocalStreams();
     [Measure] sequence<MediaStream> getRemoteStreams();
     [DeprecateAs=V8RTCPeerConnection_GetStreamById_Method] MediaStream getStreamById(DOMString streamId);
     [Measure, CallWith=ScriptState, RaisesException] void addStream(MediaStream? stream, optional Dictionary mediaConstraints);
     [Measure, RaisesException] void removeStream(MediaStream? stream);
     [Measure, RaisesException] RTCDTMFSender createDTMFSender(MediaStreamTrack track);
     attribute EventHandler onaddstream;
     attribute EventHandler onremovestream;
 };