Make scrollAnimatorEnabled work on Mac like it does on other platforms

base/mac/mac_util.mm

 // Copyright (c) 2012 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.
 
 #include "base/mac/mac_util.h"
 
 #import <Cocoa/Cocoa.h>
 #import <IOKit/IOKitLib.h>
 #include <errno.h>
 #include <stddef.h>
@@ skipping 585 matching lines @@
           StringPiece(begin + number_loc, begin + comma_loc), &major_tmp) ||
       !StringToInt(
           StringPiece(begin + comma_loc + 1, ident.end()), &minor_tmp))
     return false;
   *type = ident.substr(0, number_loc);
   *major = major_tmp;
   *minor = minor_tmp;
   return true;
 }
 
+bool IsScrollAnimationEnabled() {
+  bool enabled = false;
+  id value = nil;
+  if (base::mac::IsOSMountainLionOrLater()) {
+    value = [[NSUserDefaults standardUserDefaults]
+        objectForKey:@"NSScrollAnimationEnabled"];
+  } else {
+    value = [[NSUserDefaults standardUserDefaults]
+        objectForKey:@"AppleScrollAnimationEnabled"];
+  }
+  if (value)
+    enabled = [value boolValue];
+  return enabled;
+}
+
+
 }  // namespace mac
 }  // namespace base