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

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

Index: chrome/browser/media/router/mojo/media_route_controller.cc
diff --git a/chrome/browser/media/router/mojo/media_route_controller.cc b/chrome/browser/media/router/mojo/media_route_controller.cc
index 425dcd4ab99568b99f52078d4c02274af23194af..9385272ebb83fdeec6863a32f3bf3569fb6bb947 100644
--- a/chrome/browser/media/router/mojo/media_route_controller.cc
+++ b/chrome/browser/media/router/mojo/media_route_controller.cc
@@ -69,6 +69,7 @@ void MediaRouteController::SetVolume(float volume) const {
 
 void MediaRouteController::OnMediaStatusUpdated(const MediaStatus& status) {
   DCHECK(is_valid_);
+  current_media_status_ = base::make_optional<MediaStatus>(MediaStatus(status));

[mark a. foltz, 2017/05/12 23:06:18]

I don't think make_optional adds much here.
It looks like 
current_media_status_ = MediaStatus(status) should suffice (or std::move(status)
if it is move-only).

[takumif, 2017/05/15 17:57:29]

Done.

   for (Observer& observer : observers_)
     observer.OnMediaStatusUpdated(status);
 }