Mac: Add rails for scrolling.

content/content_browser.gypi

 # 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.
 
 {
   'dependencies': [
     '../base/base.gyp:base_static',
     '../crypto/crypto.gyp:crypto',
     '../device/vibration/vibration.gyp:device_vibration',
     '../device/vibration/vibration.gyp:device_vibration_mojo_bindings',
@@ skipping 1068 matching lines @@
       'browser/renderer_host/input/input_router.h',
       'browser/renderer_host/input/input_router_client.h',
       'browser/renderer_host/input/input_router_config_helper.cc',
       'browser/renderer_host/input/input_router_config_helper.h',
       'browser/renderer_host/input/input_router_impl.cc',
       'browser/renderer_host/input/input_router_impl.h',
       'browser/renderer_host/input/motion_event_android.cc',
       'browser/renderer_host/input/motion_event_android.h',
       'browser/renderer_host/input/motion_event_web.cc',
       'browser/renderer_host/input/motion_event_web.h',
+      'browser/renderer_host/input/mouse_wheel_rails_filter_mac.cc',
+      'browser/renderer_host/input/mouse_wheel_rails_filter_mac.h',
       'browser/renderer_host/input/stylus_text_selector.cc',
       'browser/renderer_host/input/stylus_text_selector.h',
       'browser/renderer_host/input/synthetic_gesture.cc',
       'browser/renderer_host/input/synthetic_gesture.h',
       'browser/renderer_host/input/synthetic_gesture_controller.cc',
       'browser/renderer_host/input/synthetic_gesture_controller.h',
       'browser/renderer_host/input/synthetic_gesture_target.h',
       'browser/renderer_host/input/synthetic_gesture_target_android.cc',
       'browser/renderer_host/input/synthetic_gesture_target_android.h',
       'browser/renderer_host/input/synthetic_gesture_target_aura.cc',
@@ skipping 907 matching lines @@
         'browser/media/media_web_contents_observer.h',
       ],
     }],
     ['OS == "linux" and use_openssl==1', {
       'dependencies': [
         '../third_party/boringssl/boringssl.gyp:boringssl',
       ],
     }],
   ],
 }