[Media Router Tests] Add tests for MediaRouterFactory.

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 1416 matching lines @@
       'browser/supervised_user/legacy/supervised_user_registration_utility_unittest.cc',
       'browser/supervised_user/legacy/supervised_user_shared_settings_service_unittest.cc',
       'browser/supervised_user/legacy/supervised_user_shared_settings_update_unittest.cc',
       'browser/supervised_user/legacy/supervised_user_sync_service_unittest.cc',
     ],
     'chrome_unit_tests_media_router_sources': [
       'browser/media/router/create_presentation_connection_request_unittest.cc',
       'browser/media/router/issue_manager_unittest.cc',
       'browser/media/router/issue_unittest.cc',
       'browser/media/router/media_route_unittest.cc',
+      'browser/media/router/media_router_factory_unittest.cc',
       'browser/media/router/media_sink_unittest.cc',
       'browser/media/router/media_sinks_observer_unittest.cc',
       'browser/media/router/media_source_helper_unittest.cc',
       'browser/media/router/media_source_unittest.cc',
       'browser/media/router/presentation_media_sinks_observer_unittest.cc',
       'browser/media/router/presentation_request_unittest.cc',
       'browser/media/router/presentation_service_delegate_impl_unittest.cc',
     ],
     'chrome_unit_tests_media_router_non_android_sources': [
       'browser/media/router/mojo/media_router_mojo_impl_unittest.cc',
@@ skipping 1556 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }