Revert of Don't handle NaturalScroll in Chrome but pass it to CMT instead

chrome/browser/chromeos/system/fake_input_device_settings.cc

 // Copyright 2014 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/chromeos/system/fake_input_device_settings.h"
 
 namespace chromeos {
 namespace system {
 
 FakeInputDeviceSettings::FakeInputDeviceSettings() {}
@@ skipping 28 matching lines @@
   settings.SetThreeFingerClick(enabled);
   UpdateTouchpadSettings(settings);
 }
 
 void FakeInputDeviceSettings::SetTapDragging(bool enabled) {
   TouchpadSettings settings;
   settings.SetTapDragging(enabled);
   UpdateTouchpadSettings(settings);
 }
 
-void FakeInputDeviceSettings::SetNaturalScroll(bool enabled) {
-  TouchpadSettings settings;
-  settings.SetNaturalScroll(enabled);
-  UpdateTouchpadSettings(settings);
-}
-
 void FakeInputDeviceSettings::MouseExists(
     const DeviceExistsCallback& callback) {
   callback.Run(false);
 }
 
 void FakeInputDeviceSettings::UpdateMouseSettings(
     const MouseSettings& settings) {
   current_mouse_settings_.Update(settings, NULL);
 }
 
@@ skipping 14 matching lines @@
 }
 
 void FakeInputDeviceSettings::ReapplyTouchpadSettings() {
 }
 
 void FakeInputDeviceSettings::ReapplyMouseSettings() {
 }
 
 }  // namespace system
 }  // namespace chromeos