[Media Router] Add experiment control logic.

chrome/chrome_browser.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': {
     # All .cc, .h, .m, and .mm files under browser except for:
     # * tests and mocks.
     # * code below browser/chromeos
     # * code below browser/extensions
@@ skipping 626 matching lines @@
       'browser/media/media_url_constants.cc',
       'browser/media/media_url_constants.h',
       'browser/media/midi_permission_context.cc',
       'browser/media/midi_permission_context.h',
       'browser/media/midi_permission_context_factory.cc',
       'browser/media/midi_permission_context_factory.h',
       'browser/media/native_desktop_media_list.cc',
       'browser/media/native_desktop_media_list.h',
       'browser/media/permission_bubble_media_access_handler.cc',
       'browser/media/permission_bubble_media_access_handler.h',
+      'browser/media/router/media_router_feature.cc',
+      'browser/media/router/media_router_feature.h',
       # TODO(brettw) should this go with the webrtc sources?
       'browser/media/webrtc_log_list.cc',
       'browser/media/webrtc_log_list.h',
       'browser/memory_details.cc',
       'browser/memory_details.h',
       'browser/memory_details_android.cc',
       'browser/memory_details_linux.cc',
       'browser/memory_details_mac.cc',
       'browser/memory_details_win.cc',
       'browser/mod_pagespeed/mod_pagespeed_metrics.cc',
@@ skipping 3458 matching lines @@
             '../components/components.gyp:omnibox_browser',
             '../components/components.gyp:rlz',
             '../components/components.gyp:search_engines',
             '../rlz/rlz.gyp:rlz_lib',
           ],
         },
       ],
     }],
   ],
 }