Remove the default wheel event handler from blink.

third_party/WebKit/Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 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:
  *
  *     * 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 667 matching lines @@
         syntheticWheel.wheelTicksY = delta.height / tickDivisor;
         syntheticWheel.hasPreciseScrollingDeltas = true;
         syntheticWheel.x = m_positionOnFlingStart.x;
         syntheticWheel.y = m_positionOnFlingStart.y;
         syntheticWheel.globalX = m_globalPositionOnFlingStart.x;
         syntheticWheel.globalY = m_globalPositionOnFlingStart.y;
         syntheticWheel.modifiers = m_flingModifier;
 
         if (handleMouseWheel(*m_page->deprecatedLocalMainFrame(), syntheticWheel) != WebInputEventResult::NotHandled)
             return true;
-        if (!m_webSettings->wheelGesturesEnabled())
-            return false;
 
         // TODO(dtapuska): Remove these GSB/GSE sequences when trackpad latching is implemented; see crbug.com/526463.
         WebGestureEvent syntheticScrollBegin = createGestureScrollEventFromFling(WebInputEvent::GestureScrollBegin, WebGestureDeviceTouchpad);
         syntheticScrollBegin.data.scrollBegin.deltaXHint = delta.width;
         syntheticScrollBegin.data.scrollBegin.deltaYHint = delta.height;
         syntheticScrollBegin.data.scrollBegin.inertialPhase = WebGestureEvent::MomentumPhase;
         handleGestureEvent(syntheticScrollBegin);
 
         WebGestureEvent syntheticScrollUpdate = createGestureScrollEventFromFling(WebInputEvent::GestureScrollUpdate, WebGestureDeviceTouchpad);
         syntheticScrollUpdate.data.scrollUpdate.deltaX = delta.width;
@@ skipping 3853 matching lines @@
 {
     // TODO(oshima): Investigate if this should return the ScreenInfo's scale factor rather than
     // page's scale factor, which can be 1 in use-zoom-for-dsf mode.
     if (!page())
         return 1;
 
     return page()->deviceScaleFactor();
 }
 
 } // namespace blink