Call Device.SetCarrier when the ONC Carrier property is specified.

extensions/common/api/networking_private.idl

 // 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.
 
 // The <code>chrome.networkingPrivate</code> API is used for configuring
 // network connections (Cellular, Ethernet, VPN, WiFi or WiMAX). This private
 // API is only valid if called from a browser or app associated with the
 // primary user. See the Open Network Configuration (ONC) documentation for
 // descriptions of properties: 
 // <a href="https://code.google.com/p/chromium/codesearch#chromium/src/components/onc/docs/onc_spec.html">
@@ skipping 42 matching lines @@
     DOMString? Language;
     DOMString? LocalizedName;
     DOMString? Name;
     DOMString? Password;
     DOMString? Username;
   };
 
   dictionary CellularConfigProperties {
     boolean? AutoConnect;
     APNProperties? APN;
+
+    // Specifies which carrier to use for Cellular configurations that support
+    // multiple carriers. May be set with $(ref:setProperties), but will be
+    // ignored by $(ref:createConfiguration).
+    DOMString? Carrier;
   };
 
   dictionary CellularStateProperties {
     ActivationStateType? ActivationState;
     DOMString? NetworkTechnology;
     DOMString? RoamingState;
     long? SignalStrength;
   };
 
   dictionary EthernetStateProperties {
@@ skipping 335 matching lines @@
     // Fired when the list of networks has changed.  Sends a complete list of
     // GUIDs for all the current networks.
     static void onNetworkListChanged(DOMString[] changes);
 
     // Fired when a portal detection for a network completes. Sends the guid of
     // the network and the corresponding captive portal status.
     static void onPortalDetectionCompleted(DOMString networkGuid,
                                            CaptivePortalStatus status);
   };
 };