[Media Router] Implement an internal Media Routes observer.

chrome/browser/media/router/mojo/media_router_type_converters.cc

Index: chrome/browser/media/router/mojo/media_router_type_converters.cc
diff --git a/chrome/browser/media/router/mojo/media_router_type_converters.cc b/chrome/browser/media/router/mojo/media_router_type_converters.cc
index e49ebb1db2b39687e8169c31dcd268aeb2a8be87..c82de76d57e966cd2da5542c3ed8dbbd84422257 100644
--- a/chrome/browser/media/router/mojo/media_router_type_converters.cc
+++ b/chrome/browser/media/router/mojo/media_router_type_converters.cc
@@ -183,6 +183,8 @@ media_router::RouteRequestResult::ResultCode RouteRequestResultCodeFromMojo(
       return media_router::RouteRequestResult::OK;
     case RouteRequestResultCode::TIMED_OUT:
       return media_router::RouteRequestResult::TIMED_OUT;
+    case RouteRequestResultCode::ROUTE_NOT_FOUND:
+      return media_router::RouteRequestResult::ROUTE_NOT_FOUND;
     default:
       NOTREACHED() << "Unknown RouteRequestResultCode " << result_code;
       return media_router::RouteRequestResult::UNKNOWN_ERROR;