[MR] Add description field to MediaSink.

chrome/browser/media/router/media_router.mojom

 // 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.
 
 module media_router.interfaces;
 
 // Represents an output sink to which media can be routed.
 struct MediaSink {
   enum IconType {
     CAST,
     CAST_AUDIO,
     CAST_AUDIO_GROUP,
     GENERIC,
     HANGOUT
   };
 
   // The sink identifier, e.g. "rs71w7mFzYLFlabir_qO4NHl6SUc."
   string sink_id;
   // The human-readable name, e.g. "Janet's Chromecast".
   string name;
+  // Optional description of the sink.
+  string? description;
   // The type of icon to show in the UI for this media sink.
   IconType icon_type;
 };
 
 // Should be kept in sync with media_route.h.
 struct MediaRoute {
   // The ID of this media route, e.g. "r_PR1O_blkC9dsKp-tb1ti8qurOo".
   string media_route_id;
   // The ID of the media source being sent through this media route.
   // May be missing if route is not local.
@@ skipping 194 matching lines @@
 
   // Called when the overall availability of media sinks has been updated.
   OnSinkAvailabilityUpdated(SinkAvailability availability);
 
   // Called when the state of presentation connected to route |route_id| has
   // changed to |state|.
   OnPresentationConnectionStateChanged(
       string route_id, PresentationConnectionState state);
 };