Converts ash/wm/mru_window_tracker_unittest.cc to use AshTest

ash/mus/property_util.cc

Index: ash/mus/property_util.cc
diff --git a/ash/mus/property_util.cc b/ash/mus/property_util.cc
index 4d199df8083c76b9cb84b64d5eb6fb534807f171..ea9a2e5812f289ebdc94b25b65b9aabebe1db5e1 100644
--- a/ash/mus/property_util.cc
+++ b/ash/mus/property_util.cc
@@ -265,5 +265,17 @@ int64_t GetInitialDisplayId(const ui::Window::SharedProperties& properties) {
                                   : mojo::ConvertTo<int64_t>(iter->second);
 }
 
+void SetExcludeFromMru(ui::Window* window, bool value) {
+  window->SetSharedProperty<bool>(
+      ui::mojom::WindowManager::kExcludeFromMru_Property, value);
+}
+
+bool GetExcludeFromMru(const ui::Window* window) {
+  return window->HasSharedProperty(
+             ui::mojom::WindowManager::kExcludeFromMru_Property) &&
+         window->GetSharedProperty<bool>(
+             ui::mojom::WindowManager::kExcludeFromMru_Property);
+}
+
 }  // namespace mus
 }  // namespace ash