Update VTTCue enum AlignSetting, "middle" -> "center"

third_party/WebKit/Source/core/html/track/vtt/VTTCue.idl

 /*
  * Copyright (c) 2013, Opera Software ASA. 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 15 matching lines @@
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 // https://w3c.github.io/webvtt/#the-vttcue-interface
 
 enum AutoKeyword { "auto" };
 enum DirectionSetting { "" /* horizontal */, "rl", "lr" };
 // enum LineAlignSetting { "start", "middle", "end" };
 // enum PositionAlignSetting { "start", "middle", "end", "auto" };
-enum AlignSetting { "start", "middle", "end", "left", "right" };
+enum AlignSetting { "start", "center", "end", "left", "right" };
 
 [
     Constructor(double startTime, double endTime, DOMString text),
     ConstructorCallWith=Document,
     DependentLifetime,
 ] interface VTTCue : TextTrackCue {
     [RuntimeEnabled=WebVTTRegions] attribute VTTRegion? region;
     attribute DirectionSetting vertical;
     attribute boolean snapToLines;
     attribute (double or AutoKeyword) line;
     // attribute LineAlignSetting lineAlign;
     [RaisesException=Setter] attribute (double or AutoKeyword) position;
     // attribute PositionAlignSetting positionAlign;
     [RaisesException=Setter] attribute double size;
     attribute AlignSetting align;
     attribute DOMString text;
     DocumentFragment getCueAsHTML();
 };