Make DownloadHistory observe manager, items

chrome/chrome_tests.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.
 {
   'variables' : {
     'pyautolib_sources': [
       'app/chrome_command_ids.h',
       'app/chrome_dll_resource.h',
       'common/automation_constants.h',
       'common/pref_names.cc',
@@ skipping 2682 matching lines @@
         'browser/chromeos/media/media_player_browsertest.cc',
         'browser/chromeos/oom_priority_manager_browsertest.cc',
         'browser/chromeos/process_proxy/process_proxy_browsertest.cc',
         'browser/chromeos/ui/idle_logout_dialog_view_browsertest.cc',
         'browser/collected_cookies_browsertest.cc',
         'browser/content_settings/content_settings_browsertest.cc',
         'browser/crash_recovery_browsertest.cc',
         'browser/custom_handlers/protocol_handler_registry_browsertest.cc',
         'browser/debugger/devtools_sanity_browsertest.cc',
         'browser/download/download_browsertest.cc',
+        'browser/download/download_history_unittest.cc',
         'browser/download/download_danger_prompt_browsertest.cc',
         'browser/extensions/api/downloads/downloads_api_unittest.cc',
         'browser/download/download_query_unittest.cc',
         'browser/download/download_test_observer.cc',
         'browser/download/save_page_browsertest.cc',
         'browser/errorpage_browsertest.cc',
         'browser/extensions/active_tab_apitest.cc',
         'browser/extensions/alert_apitest.cc',
         'browser/extensions/all_urls_apitest.cc',
         'browser/extensions/api/app/app_apitest.cc',
@@ skipping 1946 matching lines @@
                 '--result', '<@(_outputs)',
                 '--isolate', 'browser_tests.isolate',
               ],
             },
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }