feat(iframe-api): Add deviceListChanged event.

modules/API/API.js

@@ -386,6 +386,19 @@ class API {
         });
     }
 
+    /**
+     * Notify external application (if API is enabled) that the device list has
+     * changed.
+     *
+     * @param {Object} devices - The new device list.
+     * @returns {void}
+     */
+    notifyDeviceListChanged(devices: Object) {
+        this._sendEvent({
+            name: 'device-list-changed',
+            devices });
+    }
+
     /**
      * Notify external application (if API is enabled) that user changed their
      * nickname.

modules/API/external/external_api.js

@@ -50,6 +50,7 @@ const events = {
     'avatar-changed': 'avatarChanged',
     'audio-availability-changed': 'audioAvailabilityChanged',
     'audio-mute-status-changed': 'audioMuteStatusChanged',
+    'device-list-changed': 'deviceListChanged',
     'display-name-change': 'displayNameChange',
     'email-change': 'emailChange',
     'feedback-submitted': 'feedbackSubmitted',