[Media Router] Unit tests for sticky cast modes

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 452b802f5773eaa1f0c1226328519ca0297ea682..badd597883f88b65c4bcb6a99aeb7e8f3fa57be9 100644
--- a/chrome/browser/ui/webui/media_router/media_router_ui.cc
+++ b/chrome/browser/ui/webui/media_router/media_router_ui.cc
@@ -725,6 +725,10 @@ std::string MediaRouterUI::GetTruncatedPresentationRequestSourceName() const {
              : TruncateHost(GetHostFromURL(gurl));
 }
 
+const std::set<MediaCastMode>& MediaRouterUI::cast_modes() const {
+  return cast_modes_;
+}
+
 const std::string& MediaRouterUI::GetRouteProviderExtensionId() const {
   // TODO(crbug.com/597778): remove reference to MediaRouterMojoImpl
   return static_cast<MediaRouterMojoImpl*>(router_)