[Media Router] Return NotFoundError on dialog exit if appropriate

chrome/test/media_router/media_router_tests.gypi

 # Copyright 2015 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': {
     'media_router_integration_test_resources': [
       'resources/basic_test.html',
       'resources/close_route_with_error_on_send.json',
       'resources/common.js',
       'resources/fail_create_route.json',
       'resources/fail_reconnect_session.html',
       'resources/fail_reconnect_session.json',
       'resources/no_provider.json',
+      'resources/no_sinks.json',
+      'resources/no_supported_sinks.json',
       'resources/route_creation_timed_out.json',
     ],
     'media_router_test_extension_resources': [
       'telemetry/extension/manifest.json',
       'telemetry/extension/script.js',
     ],
   }, # end of variables
   'targets': [
     {
       'target_name': 'media_router_integration_test_files',
@@ skipping 26 matching lines @@
         {
           'destination': '<(output_dir)',
           'files': [
             '<@(resource_files)',
           ],
         },
       ],
     },  # end of target 'media_router_test_extension_files'
   ],  # end of targets
 }