MD Downloads: track downloads in C++, dispatch discrete JS updates

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.
 {
   'variables': {
     'chrome_unit_tests_sources': [
       # histograms.xml is analyzed by AboutFlagsHistogramTest, so this
       # dependency is needed to make commit bots run unit_tests on
       # histograms.xml changes.
       '../tools/metrics/histograms/histograms.xml',
@@ skipping 1555 matching lines @@
       'browser/ui/toolbar/test_toolbar_model.cc',
       'browser/ui/toolbar/test_toolbar_model.h',
       'browser/ui/toolbar/toolbar_actions_bar_unittest.cc',
       'browser/ui/toolbar/toolbar_actions_bar_unittest.h',
       'browser/ui/toolbar/toolbar_actions_model_unittest.cc',
       'browser/ui/toolbar/toolbar_model_unittest.cc',
       'browser/ui/website_settings/permission_bubble_manager_unittest.cc',
       'browser/ui/website_settings/permission_menu_model_unittest.cc',
       'browser/ui/webui/downloads_util_unittest.cc',
       'browser/ui/webui/help/version_updater_chromeos_unittest.cc',
+      'browser/ui/webui/md_downloads/downloads_list_tracker_unittest.cc',
       'browser/ui/webui/ntp/ntp_user_data_logger_unittest.cc',
       'browser/ui/webui/options/autofill_options_handler_unittest.cc',
       'browser/ui/webui/options/clear_browser_data_handler_unittest.cc',
       'browser/ui/webui/options/language_options_handler_unittest.cc',
       'browser/ui/webui/options/pepper_flash_content_settings_utils_unittest.cc',
       'browser/ui/webui/options/sync_setup_handler_unittest.cc',
       'browser/ui/webui/settings/sync_handler_unittest.cc',
       'browser/ui/webui/signin/login_ui_service_unittest.cc',
       'browser/ui/webui/web_dialog_web_contents_delegate_unittest.cc',
       'browser/ui/window_sizer/window_sizer_common_unittest.cc',
@@ skipping 1399 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }