Introduce a helper for OPENFILENAME struct to make certain logic testable.

ui/ui_unittests.gyp

 # Copyright 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': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 93 matching lines @@
                 'test_data_prefix' : 'ui',
               },
               'includes': [ '../build/copy_test_data_ios.gypi' ],
             },
           ],
         }],
         ['OS == "win"', {
           'sources': [
             'base/dragdrop/os_exchange_data_win_unittest.cc',
             'base/win/hwnd_subclass_unittest.cc',
+            'base/win/open_file_name_win_unittest.cc',
             'gfx/color_profile_win_unittest.cc',
             'gfx/font_fallback_win_unittest.cc',
             'gfx/icon_util_unittest.cc',
             'gfx/icon_util_unittests.rc',
             'gfx/platform_font_win_unittest.cc',
           ],
           'include_dirs': [
             '../..',
             '../third_party/wtl/include',
           ],
@@ skipping 143 matching lines @@
           ],
           'variables': {
             'test_suite_name': 'ui_unittests',
           },
           'includes': [ '../build/apk_test.gypi' ],
         },
       ],
     }],
   ],
 }