Make scrollAnimatorEnabled work on Mac like it does on other platforms

third_party/WebKit/Source/platform/mac/ScrollAnimatorMac.mm

 /*
  * Copyright (C) 2010, 2011 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 710 matching lines @@
         [m_verticalScrollbarPainterDelegate.get() invalidate];
         [m_scrollAnimationHelperDelegate.get() invalidate];
         END_BLOCK_OBJC_EXCEPTIONS;
     }
     m_initialScrollbarPaintTimer.stop();
     m_sendContentAreaScrolledTimer.stop();
 }
 
 ScrollResultOneDimensional ScrollAnimatorMac::userScroll(ScrollbarOrientation orientation, ScrollGranularity granularity, float step, float delta)
 {
-    bool scrollAnimationEnabledForSystem = static_cast<ScrollbarThemeMacCommon&>(
-                                               ScrollbarTheme::theme())
-                                               .scrollAnimationEnabledForSystem();
     m_haveScrolledSincePageLoad = true;
 
-    if (!scrollAnimationEnabledForSystem || !m_scrollableArea->scrollAnimatorEnabled())
+    if (!m_scrollableArea->scrollAnimatorEnabled())
         return ScrollAnimatorBase::userScroll(orientation, granularity, step, delta);
 
     if (granularity == ScrollByPixel || granularity == ScrollByPrecisePixel)
         return ScrollAnimatorBase::userScroll(orientation, granularity, step, delta);
 
     float currentPos = orientation == HorizontalScrollbar ? m_currentPosX : m_currentPosY;
     float usedPixelDelta = computeDeltaToConsume(orientation, step * delta);
     float newPos = currentPos + usedPixelDelta;
     if (currentPos == newPos)
         return ScrollResultOneDimensional(false);
@@ skipping 434 matching lines @@
         return;
 
     m_visibleScrollerThumbRect = rectInViewCoordinates;
 }
 
 bool ScrollAnimatorMac::canUseCoordinatedScrollbar() {
     return ScrollbarThemeMacCommon::isOverlayAPIAvailable();
 }
 
 } // namespace blink