ozone: Move the factory interfaces into a common target.

ui/ozone/platform/test/test.gypi

 # 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.
 
 {
   'variables': {
     'internal_ozone_platform_deps': [
       'ozone_platform_test',
     ],
     'internal_ozone_platforms': [
       'test'
     ],
   },
   'targets': [
     {
       'target_name': 'ozone_platform_test',
       'type': 'static_library',
       'defines': [
         'OZONE_IMPLEMENTATION',
       ],
       'dependencies': [
         '../../base/base.gyp:base',
         '../events/events.gyp:events',
         '../events/ozone/events_ozone.gyp:events_ozone_evdev',
         '../gfx/gfx.gyp:gfx',
       ],
       'sources': [
+        'file_surface_factory.cc',
+        'file_surface_factory.h',
         'ozone_platform_test.cc',
         'ozone_platform_test.h',
       ],
     },
   ],
 }