Make scrollAnimatorEnabled work on Mac like it does on other platforms

content/browser/renderer_host/render_process_host_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 250 matching lines @@
   void GetAudioOutputControllers(
       const GetAudioOutputControllersCallback& callback) const override;
 
   BluetoothDispatcherHost* GetBluetoothDispatcherHost();
 
 #if defined(OS_POSIX) && !defined(OS_ANDROID) && !defined(OS_MACOSX)
   // Launch the zygote early in the browser startup.
   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_;
 
   // True if fast shutdown has been performed on this RPH.
   bool fast_shutdown_started_;
 
   // True if we've posted a DeleteTask and will be deleted soon.
   bool deleting_soon_;
 
@@ skipping 231 matching lines @@
 #endif
 
   base::WeakPtrFactory<RenderProcessHostImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderProcessHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_