Expose scroll customization for touch to JS (behind REF).

Source/core/page/scrolling/ScrollState.idl

 // 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.
 
-// http://dev.w3.org/houdini/css-scroll-api/
+// https://goo.gl/1ipTpP

[haraken, 2015/07/15 00:15:18]

Can we use a full URL?

[tdresser, 2015/07/15 14:04:54]

Done.

[skobes, 2015/07/15 19:52:40]

@haraken: Just curious, why do you want the full URL?  (I prefer the short URL
for readability, but I don't feel strongly about it.)

[haraken, 2015/07/15 23:33:19]

That's just a convention. We've been adding a full URL in Blink IDL files (which
is helpful to see if the spec is a whatwg one or a w3c one etc).

 
 [
     Constructor(optional double deltaX = 0,
                 optional double deltaY = 0,
                 optional double deltaGranularity = 0,
                 optional double velocityX = 0,
                 optional double velocityY = 0,
                 optional boolean inInertialPhase = false,
                 optional boolean isBeginning = false,
                 optional boolean isEnding = false),
     WillBeGarbageCollected,
     RuntimeEnabled=ScrollCustomization
 ] interface ScrollState {
     readonly attribute double deltaX;
     readonly attribute double deltaY;
     readonly attribute double deltaGranularity;
     readonly attribute double velocityX;
     readonly attribute double velocityY;
     readonly attribute boolean inInertialPhase;
     readonly attribute boolean isEnding;
     readonly attribute boolean isBeginning;
     readonly attribute boolean fromUserInput;
     readonly attribute boolean shouldPropagate;
 
     [RaisesException] void consumeDelta(double x, double y);
-    // FIXME: implement distributeToScrollChainDescendent.
+    void distributeToScrollChainDescendant();
 };