Move download filename determintion into a separate class.

chrome/chrome_tests_unit.gypi

 # Copyright 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.
 {
   'targets': [
     {
       # This target contains mocks and test utilities that don't belong in
       # production libraries but are used by more than one test executable.
       'target_name': 'test_support_common',
       'type': 'static_library',
@@ skipping 681 matching lines @@
         'browser/download/chrome_download_manager_delegate_unittest.cc',
         'browser/download/download_item_model_unittest.cc',
         'browser/download/all_download_item_notifier_unittest.cc',
         'browser/download/download_history_unittest.cc',
         'browser/download/download_query_unittest.cc',
         'browser/download/download_request_infobar_delegate_unittest.cc',
         'browser/download/download_request_limiter_unittest.cc',
         'browser/download/download_path_reservation_tracker_unittest.cc',
         'browser/download/download_shelf_unittest.cc',
         'browser/download/download_status_updater_unittest.cc',
+        'browser/download/download_target_determiner_unittest.cc',
         'browser/download/download_ui_controller_unittest.cc',
         'browser/enumerate_modules_model_unittest_win.cc',
         'browser/extensions/active_tab_unittest.cc',
         'browser/extensions/activity_database_unittest.cc',
         'browser/extensions/activity_log_unittest.cc',
         'browser/extensions/admin_policy_unittest.cc',
         'browser/extensions/api/alarms/alarms_api_unittest.cc',
         'browser/extensions/api/api_resource_manager_unittest.cc',
         'browser/extensions/api/bluetooth/bluetooth_event_router_unittest.cc',
         'browser/extensions/api/bookmarks/bookmark_api_helpers_unittest.cc',
@@ skipping 1760 matching lines @@
               # more details.
               'DebugInformationFormat': '3',
               'ProgramDataBaseFileName': '<(PRODUCT_DIR)/unit_tests.exe.pdb',
             },
           },
         },
       ],
     }],
   ],  # 'conditions'
 }