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

mash/system_ui/system_ui.cc

Index: mash/system_ui/system_ui.cc
diff --git a/mash/system_ui/system_ui.cc b/mash/system_ui/system_ui.cc
index 6c4852e3ebeb1ab8d6346bfa61626ac77baf5006..a9284555474620cc525372877a6830c19d915cc3 100644
--- a/mash/system_ui/system_ui.cc
+++ b/mash/system_ui/system_ui.cc
@@ -33,11 +33,11 @@ class DesktopBackground : public views::WidgetDelegateView {
     std::map<std::string, std::vector<uint8_t>> properties;
     properties[mash::wm::mojom::kWindowContainer_Property] =
         mojo::TypeConverter<const std::vector<uint8_t>, int32_t>::Convert(
-            mash::wm::mojom::CONTAINER_USER_BACKGROUND);
+            static_cast<int32_t>(mash::wm::mojom::Container::USER_BACKGROUND));
     mus::Window* window =
         views::WindowManagerConnection::Get()->NewWindow(properties);
     params.native_widget = new views::NativeWidgetMus(
-        widget, shell, window, mus::mojom::SURFACE_TYPE_DEFAULT);
+        widget, shell, window, mus::mojom::SurfaceType::DEFAULT);
     widget->Init(params);
     widget->Show();
   }
@@ -68,11 +68,11 @@ class Shelf : public views::WidgetDelegateView {
     std::map<std::string, std::vector<uint8_t>> properties;
     properties[mash::wm::mojom::kWindowContainer_Property] =
         mojo::TypeConverter<const std::vector<uint8_t>, int32_t>::Convert(
-            mash::wm::mojom::CONTAINER_USER_SHELF);
+            static_cast<int32_t>(mash::wm::mojom::Container::USER_SHELF));
     mus::Window* window =
         views::WindowManagerConnection::Get()->NewWindow(properties);
     params.native_widget = new views::NativeWidgetMus(
-        widget, shell, window, mus::mojom::SURFACE_TYPE_DEFAULT);
+        widget, shell, window, mus::mojom::SurfaceType::DEFAULT);
     widget->Init(params);
     widget->Show();
   }