Add permission "mediaRouterPrivate" for the Media Router Mojo service.

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 620 matching lines @@
   "mediaGalleries.delete": {
     "channel": "stable",
     "extension_types": [ "platform_app" ]
   },
   "mediaPlayerPrivate": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app", "platform_app"],
     "location": "component",
     "platforms": ["chromeos"]
   },
+  "mediaRouterPrivate": {
+    "channel": "stable",
+    "extension_types": ["platform_app", "extension"],

[Devlin, 2015/04/02 21:06:50]

Do we need multiple extension types when there's only one whitelist?

[Kevin M, 2015/04/02 21:32:07]

Done.

+    "whitelist": [
+      "63ED55E43214C211F82122ED56407FF1A807F2A3"   // http://crbug.com/448569
+    ]
+  },
   "metricsPrivate": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app", "platform_app"],
     "whitelist": [
       // The file manager and Google Now are component extensions, and they can
       // currently use whitelisted interfaces without being on the corresponding
       // whitelist.
       // Adding it to this whitelist documents their dependency, however, and
       // also doesn't hurt anything.
       "A948368FC53BE437A55FEB414106E207925482F5",  // File manager
@@ skipping 323 matching lines @@
   },
   "webstorePrivate": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app", "hosted_app"],
     "whitelist": [
       "B44D08FD98F1523ED5837D78D0A606EA9D6206E5",  // Web Store
       "2653F6F6C39BC6EEBD36A09AFB92A19782FF7EB4"   // Enterprise Web Store
     ]
   }
 }