Whitelist MR extensions for settingsPrivate API.

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 906 matching lines @@
     "location": "component"
   },
   "screensaver": {
     "channel": "stable",
     "extension_types": ["legacy_packaged_app", "hosted_app", "platform_app"]
   },
   "sessions": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
   },
-  "settingsPrivate": {
-    "channel": "trunk",
-    "extension_types": ["extension", "platform_app"],
-    "location": "component"
-  },
+  "settingsPrivate": [

[Devlin, 2016/01/28 22:55:59]

We're quite inconsistent in style, but I'd prefer to see us using the { on the
previous line, a la line 874.  It feels more concise.

[amp, 2016/01/28 23:09:10]

Done.

+    {
+      "channel": "trunk",
+      "extension_types": ["extension", "platform_app"],
+      "location": "component"
+    },
+    {
+      "channel": "stable",
+      "extension_types": ["extension"],
+      "whitelist": [
+        "63ED55E43214C211F82122ED56407FF1A807F2A3",  // Media Router Dev
+        "226CF815E39A363090A1E547D53063472B8279FA"   // Media Router Release
+      ]
+    }
+  ],
   "signedInDevices": {
     "channel": "dev",
     "extension_types": ["extension", "legacy_packaged_app", "platform_app"]
   },
   "streamsPrivate": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app", "platform_app"],
     "whitelist": [
       "787000072C6FBB934AF5A42275CDE73FC977D995",  // browser_tests
       "2FC374607C2DF285634B67C64A2E356C607091C3",  // QuickOffice
@@ skipping 118 matching lines @@
     "channel": "stable",
     "extension_types": ["platform_app"],
     "platforms": ["chromeos"],
     "whitelist": [
       "A948368FC53BE437A55FEB414106E207925482F5",  // Files app
       "8C726564C6DBE7380BAB388DE6CC7EC93EB44B06",  // Video player
       "5065C83E84321221675D20FBE4DC43C655CC8C6F"   // Files app tests
     ]
   }
 }