Implement Wheel Gesture Scrolling on OSX.

third_party/WebKit/public/web/WebInputEvent.h

 /*
  * Copyright (C) 2009 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 495 matching lines @@
         struct {
             // Initial motion that triggered the scroll.
             // May be redundant with deltaX/deltaY in the first scrollUpdate.
             float deltaXHint;
             float deltaYHint;
             // Default initialized to ScrollUnits::PrecisePixels.
             ScrollUnits deltaHintUnits;
             // If true, this event will skip hit testing to find a scroll
             // target and instead just scroll the viewport.
             bool targetViewport;
+            bool inertial;

[tdresser, 2016/03/02 18:26:53]

Can we add a comment indicating what this means?
Can it ever be true if the source if touch?

[dtapuska, 2016/03/07 18:03:59]

Done.

         } scrollBegin;
 
         struct {
             float deltaX;
             float deltaY;
             float velocityX;
             float velocityY;
             // Whether any previous GestureScrollUpdate in the current scroll
             // sequence was suppressed (e.g., the causal touchmove was
             // preventDefault'ed). This bit is particularly useful for
@@ skipping 78 matching lines @@
         , uniqueTouchEventId(0)
     {
     }
 };
 
 #pragma pack(pop)
 
 } // namespace blink
 
 #endif