Implementation of the DeviceInfo get 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.
 
 // See c/c/e/features/* to understand this file, in particular feature.h,
 // simple_feature.h, and base_feature_provider.h.
 
 {
   "activeTab": {
     "channel": "stable",
@@ skipping 500 matching lines @@
     "extension_types": ["packaged_app", "hosted_app", "platform_app"]
   },
   "serial": {
     "channel": "stable",
     "extension_types": ["platform_app"]
   },
   "sessionRestore": {
     "channel": "dev",
     "extension_types": ["extension", "packaged_app"]
   },
+  "signedInDevices": {
+    "channel": "dev",
+    "extension_types": ["extension", "packaged_app"]
+  },
   "streamsPrivate": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app", "platform_app"],
     "whitelist": [
       "oickdpebdnfbgkcaoklfcdhjniefkcji",  // browser_tests
       "gbkeegbaiigmenfmjfclcdgdpimamgkj",  // QuickOffice
       "ionpfmkccalenbmnddpbmocokhaknphg",  // QuickOffice Dev
       "bpmcpldpdmajfigpchkicefoigmkfalc",  // Quickoffice component extension
       "ehibbfinohgbchlgdbfpikodjaojhccn"   // Editor
     ]
@@ skipping 124 matching lines @@
   },
   "webRequestBlocking": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"]
   },
   "webview": {
     "channel": "stable",
     "extension_types": ["platform_app"]
   }
 }