[Media Router] Notify MRUI of a media status update when it starts observing

chrome/browser/ui/webui/media_router/media_router_ui.cc

Index: chrome/browser/ui/webui/media_router/media_router_ui.cc
diff --git a/chrome/browser/ui/webui/media_router/media_router_ui.cc b/chrome/browser/ui/webui/media_router/media_router_ui.cc
index 924e26a94dfd80d50b5f08d7887e5bc0983e8be5..6fe73bf5ac3b360d43371793d3078adc51da27f8 100644
--- a/chrome/browser/ui/webui/media_router/media_router_ui.cc
+++ b/chrome/browser/ui/webui/media_router/media_router_ui.cc
@@ -157,7 +157,10 @@ void MediaRouterUI::UIMediaRoutesObserver::OnRoutesUpdated(
 MediaRouterUI::UIMediaRouteControllerObserver::UIMediaRouteControllerObserver(
     MediaRouterUI* ui,
     scoped_refptr<MediaRouteController> controller)
-    : MediaRouteController::Observer(std::move(controller)), ui_(ui) {}
+    : MediaRouteController::Observer(std::move(controller)), ui_(ui) {
+  CheckForMediaStatusUpdates();

[mark a. foltz, 2017/05/12 21:00:58]

Instead you could call OnMediaStatusUpdated(controller->current_media_status()).

[takumif, 2017/05/12 22:20:58]

That would require current_media_status() to be public (and that's why I didn't
do so initially), but it does make things simpler. Done.

+}
+
 MediaRouterUI::UIMediaRouteControllerObserver::
     ~UIMediaRouteControllerObserver() {}