mash: Relay some Chrome aura window properties to Ash.

ui/views/mus/mus_client.cc

Index: ui/views/mus/mus_client.cc
diff --git a/ui/views/mus/mus_client.cc b/ui/views/mus/mus_client.cc
index 2e23362a94c80b3ec662622ef9ecd2b1fa94a4c4..743ea2847545c2f181efda5157e4b3a916845190 100644
--- a/ui/views/mus/mus_client.cc
+++ b/ui/views/mus/mus_client.cc
@@ -26,6 +26,7 @@
 #include "ui/views/mus/aura_init.h"
 #include "ui/views/mus/clipboard_mus.h"
 #include "ui/views/mus/desktop_window_tree_host_mus.h"
+#include "ui/views/mus/mus_property_mirror.h"
 #include "ui/views/mus/pointer_watcher_event_router.h"
 #include "ui/views/mus/screen_mus.h"
 #include "ui/views/views_delegate.h"
@@ -228,6 +229,10 @@ void MusClient::AddObserver(MusClientObserver* observer) {
 void MusClient::RemoveObserver(MusClientObserver* observer) {
   observer_list_.RemoveObserver(observer);
 }
+void MusClient::SetMusPropertyMirror(
+    std::unique_ptr<MusPropertyMirror> mirror) {
+  mus_property_mirror_ = std::move(mirror);
+}
 
 void MusClient::OnEmbed(
     std::unique_ptr<aura::WindowTreeHostMus> window_tree_host) {