Change mojo enums to be scoped enums in the generated C++ bindings.

components/mus/ws/window_tree_host_connection.cc

Index: components/mus/ws/window_tree_host_connection.cc
diff --git a/components/mus/ws/window_tree_host_connection.cc b/components/mus/ws/window_tree_host_connection.cc
index 6f78af3d01da0f09fb3fb10c4a04b70330cf9977..bda7e1b550a4279fad6374b4c7f457544be7f904 100644
--- a/components/mus/ws/window_tree_host_connection.cc
+++ b/components/mus/ws/window_tree_host_connection.cc
@@ -63,7 +63,7 @@ void WindowTreeHostConnectionImpl::OnDisplayInitialized() {
   connection_manager()->AddHost(this);
   set_window_tree(connection_manager()->EmbedAtWindow(
       window_tree_host()->root_window()->id(),
-      mojom::WindowTree::ACCESS_POLICY_EMBED_ROOT, std::move(client_)));
+      mojom::WindowTree::kAccessPolicyEmbedRoot, std::move(client_)));
 }
 
 }  // namespace ws