Mac: Add rails for scrolling.

content/content_tests.gypi

 # Copyright (c) 2013 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.
 
 {
   'variables': {
     'layouttest_support_content_sources': [
       'public/test/layouttest_support.h',
       'public/test/nested_message_pump_android.cc',
       'public/test/nested_message_pump_android.h',
@@ skipping 479 matching lines @@
       'browser/quota/quota_temporary_storage_evictor_unittest.cc',
       'browser/quota/storage_monitor_unittest.cc',
       'browser/quota/usage_tracker_unittest.cc',
       'browser/renderer_host/clipboard_message_filter_unittest.cc',
       'browser/renderer_host/input/gesture_event_queue_unittest.cc',
       'browser/renderer_host/input/input_router_impl_unittest.cc',
       'browser/renderer_host/input/mock_input_ack_handler.cc',
       'browser/renderer_host/input/mock_input_ack_handler.h',
       'browser/renderer_host/input/mock_input_router_client.cc',
       'browser/renderer_host/input/mock_input_router_client.h',
+      'browser/renderer_host/input/mouse_wheel_rails_filter_unittest_mac.cc',
       'browser/renderer_host/input/stylus_text_selector_unittest.cc',
       'browser/renderer_host/input/synthetic_gesture_controller_unittest.cc',
       'browser/renderer_host/input/tap_suppression_controller_unittest.cc',
       'browser/renderer_host/input/touch_action_filter_unittest.cc',
       'browser/renderer_host/input/touch_emulator_unittest.cc',
       'browser/renderer_host/input/touch_event_queue_unittest.cc',
       'browser/renderer_host/input/web_input_event_unittest.cc',
       'browser/renderer_host/input/web_input_event_util_unittest.cc',
       'browser/renderer_host/media/audio_input_device_manager_unittest.cc',
       'browser/renderer_host/media/audio_renderer_host_unittest.cc',
@@ skipping 1653 matching lines @@
                   'files': ['<(PRODUCT_DIR)/libnpapi_test_plugin.so'],
                 },
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }