[Media Router] Adds return value to mojo MediaRouteProvider::TerminateRoute.

chrome/browser/media/router/mojo/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,
@@ skipping 211 matching lines @@
                         string route_id,
                         string presentation_id,
                         string origin,
                         int32 tab_id,
                         int64 timeout_millis,
                         bool off_the_record) =>
                             (MediaRoute? route,
                              string? error_text,
                              RouteRequestResultCode result_code);
 
-  // Terminates the route specified by |route_id|.
-  TerminateRoute(string route_id);
+  // Terminates the route specified by |route_id|.  If the route was terminated
+  // successfully, |result_code| is set to OK and |error_text| is null.
+  // Otherwise, |result_code| is an error code and |error_text| describes the
+  // error.
+  TerminateRoute(string route_id) =>
+      (string? error_text, RouteRequestResultCode result_code);
 
   // Sends |message| via the media route |media_route_id|.
   // If the operation was successful, |sent| is true; otherwise it is false.
   SendRouteMessage(string media_route_id, string message) => (bool sent);
 
   // Sends |data| via the media route |media_route_id|.
   // If the operation was successful, |sent| is true; otherwise it is false.
   SendRouteBinaryMessage(string media_route_id, array<uint8> data)
       => (bool sent);
 
@@ skipping 125 matching lines @@
   // changed to |state|.
   OnPresentationConnectionStateChanged(
       string route_id, PresentationConnectionState state);
 
   // Called when the presentation connected to route |route_id| has closed.
   OnPresentationConnectionClosed(
       string route_id, PresentationConnectionCloseReason reason,
       string message);
 };