Make scrollAnimatorEnabled work on Mac like it does on other platforms

third_party/WebKit/Source/platform/scroll/ScrollbarThemeMacCommon.mm

Index: third_party/WebKit/Source/platform/scroll/ScrollbarThemeMacCommon.mm
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeMacCommon.mm b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeMacCommon.mm
index b85fcfda10bc110aee55758f0d5ee213671b7687..a1909070201e2f5d7a1f83c8fdbff19ad614586b 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeMacCommon.mm
+++ b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeMacCommon.mm
@@ -66,7 +66,6 @@ static ScrollbarSet& scrollbarSet()
 static float gInitialButtonDelay = 0.5f;
 static float gAutoscrollButtonDelay = 0.05f;
 static NSScrollerStyle gPreferredScrollerStyle = NSScrollerStyleLegacy;
-static bool gScrollAnimationEnabledForSystem = false;
 
 ScrollbarTheme& ScrollbarTheme::nativeTheme()
 {
@@ -159,12 +158,11 @@ ScrollbarThemeMacCommon::~ScrollbarThemeMacCommon()
 {
 }
 
-void ScrollbarThemeMacCommon::preferencesChanged(float initialButtonDelay, float autoscrollButtonDelay, NSScrollerStyle preferredScrollerStyle, bool redraw, bool scrollAnimationEnabled, WebScrollbarButtonsPlacement buttonPlacement)
+void ScrollbarThemeMacCommon::preferencesChanged(float initialButtonDelay, float autoscrollButtonDelay, NSScrollerStyle preferredScrollerStyle, bool redraw, WebScrollbarButtonsPlacement buttonPlacement)
 {
     updateButtonPlacement(buttonPlacement);
     gInitialButtonDelay = initialButtonDelay;
     gAutoscrollButtonDelay = autoscrollButtonDelay;
-    gScrollAnimationEnabledForSystem = scrollAnimationEnabled;
     bool sendScrollerStyleNotification = gPreferredScrollerStyle != preferredScrollerStyle;
     gPreferredScrollerStyle = preferredScrollerStyle;
     if (redraw && !scrollbarSet().isEmpty()) {
@@ -182,11 +180,6 @@ void ScrollbarThemeMacCommon::preferencesChanged(float initialButtonDelay, float
     }
 }
 
-bool ScrollbarThemeMacCommon::scrollAnimationEnabledForSystem()
-{
-    return gScrollAnimationEnabledForSystem;
-}
-
 double ScrollbarThemeMacCommon::initialAutoscrollTimerDelay()
 {
     return gInitialButtonDelay;