Make scrollAnimatorEnabled work on Mac like it does on other platforms

content/browser/renderer_host/render_process_host_impl.h

Index: content/browser/renderer_host/render_process_host_impl.h
diff --git a/content/browser/renderer_host/render_process_host_impl.h b/content/browser/renderer_host/render_process_host_impl.h
index 7eae49785e781891a79b55a1227d848701c30362..45cea6101ab38ef9770a0bbdbe868ce92fc48521 100644
--- a/content/browser/renderer_host/render_process_host_impl.h
+++ b/content/browser/renderer_host/render_process_host_impl.h
@@ -267,6 +267,8 @@ class CONTENT_EXPORT RenderProcessHostImpl
   static void EarlyZygoteLaunch();
 #endif  // defined(OS_POSIX) && !defined(OS_ANDROID) && !defined(OS_MACOSX)
 
+  void RecomputeAndUpdateWebKitPreferences();
+
  protected:
   // A proxy for our IPC::Channel that lives on the IO thread.
   scoped_ptr<IPC::ChannelProxy> channel_;