Enable chrome.mdns for Chrome Apps

chrome/common/extensions/api/_permission_features.json

 // 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.
 
 // This features file defines permissions for extension APIs implemented
 // under src/chrome.
 // See extensions/common/features/* to understand this file, in particular
 // feature.h, simple_feature.h, and base_feature_provider.h.
 
 // To add a new whitelisted ID, SHA-1 it and force it to uppercase. In Bash:
@@ skipping 660 matching lines @@
       "D2DAA9362153E8A5E3CF593E6DF4666421ABAD21",  // http://crbug.com/374965
       "D7986543275120831B39EF28D1327552FC343960",  // http://crbug.com/378067
       "A291B26E088FA6BA53FFD72F0916F06EBA7C585A",  // http://crbug.com/378067
       "62CCAAD339E6451BBF97C4BBDF758E934A05AD0B",  // Hotword triggering
       "07BD6A765FFC289FF755D7CAB2893A40EC337FEC",  // http://crbug.com/456214
       "896B85CC7E913E11C34892C1425A093C0701D386",  // http://crbug.com/456214
       "11A01C82EF355E674E4F9728A801F5C3CB40D83F",  // http://crbug.com/456214
       "F410C88469990EE7947450311D24B8AF2ADB2595"   // http://crbug.com/456214
     ]
   },
-  "mdns": {
+  "mdns": [{
     "channel": "stable",
-    "extension_types": ["extension", "platform_app"],
+    "extension_types": ["extension"],
     "whitelist": [
       "63ED55E43214C211F82122ED56407FF1A807F2A3",  // Dev
       "FA01E0B81978950F2BC5A50512FD769725F57510",  // Beta
       "B11A93E7E5B541F8010245EBDE2C74647D6C14B9",  // Canary
       "F155646B5D1CA545F7E1E4E20D573DFDD44C2540",  // Google Cast Beta
       "16CA7A47AAE4BE49B1E75A6B960C3875E945B264",  // Google Cast Stable
       "11B478CEC461C766A2DC1E5BEEB7970AE06DC9C2",  // http://crbug.com/397691
       "0EFB879311E9EFBB7C45251F89EC655711B1F6ED",  // http://crbug.com/397691
       "9193D3A51E2FE33B496CDA53EA330423166E7F02",  // http://crbug.com/397691
       "F9119B8B18C7C82B51E7BC6FF816B694F2EC3E89",  // http://crbug.com/397691
       "C17CD9E6868D7B9C67926E0EC612EA25C768418F",  // http://crbug.com/457908
       "EF2AB692559EA97C3BBDEA018A8C45F92457BD4E"   // http://crbug.com/457908
     ]
   },
+  {
+    "channel": "stable",
+    "extension_types": ["platform_app"]
+  }],
   "musicManagerPrivate": {
     "channel": "stable",
     "extension_types": ["platform_app"],
     "whitelist": [
       "4B1D0E19C6C43C008C44A8278C8B5BFE15ABEB3C", // Music Manager
       "B8F61FD1B25DE03706DBB8906A73261E4DBB992A", // Test
       "F7FA7ABC1ECB89BA8EE6656847EFABBF43BB9BCA",
       "4FE45FA56EF6A25FDE8C302C44045CA9CE8A605A",
       "3D14248405B8A59043420AAC160077C99E7788A9",
       "A6C87307BBE5886CC5F1393025000E2FE8060BF2",
@@ skipping 263 matching lines @@
   },
   "webstorePrivate": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app", "hosted_app"],
     "whitelist": [
       "B44D08FD98F1523ED5837D78D0A606EA9D6206E5",  // Web Store
       "2653F6F6C39BC6EEBD36A09AFB92A19782FF7EB4"   // Enterprise Web Store
     ]
   }
 }