Mac: Prevent NTP mousewheel events from being suppressed on Lion.

chrome/browser/platform_util_mac.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 "chrome/browser/platform_util.h"
 
 #include <Carbon/Carbon.h>
 #import <Cocoa/Cocoa.h>
 #include <CoreServices/CoreServices.h>
 
@@ skipping 136 matching lines @@
 }
 
 bool IsVisible(gfx::NativeView view) {
   // A reasonable approximation of how you'd expect this to behave.
   return (view &&
           ![view isHiddenOrHasHiddenAncestor] &&
           [view window] &&
           [[view window] isVisible]);
 }
 
+bool IsSwipeTrackingFromScrollEventsEnabled() {
+  SEL selector = @selector(isSwipeTrackingFromScrollEventsEnabled);
+  return [NSEvent respondsToSelector:selector]
+      && [NSEvent performSelector:selector];
+}
+
 }  // namespace platform_util