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

mash/wm/public/interfaces/user_window_controller.mojom

Index: mash/wm/public/interfaces/user_window_controller.mojom
diff --git a/mash/wm/public/interfaces/user_window_controller.mojom b/mash/wm/public/interfaces/user_window_controller.mojom
index 6753ceb5a369604fd5a468e334e2d072ac63c71a..1fd7cb0bcfe9ecdf623007346916c648083a3e5a 100644
--- a/mash/wm/public/interfaces/user_window_controller.mojom
+++ b/mash/wm/public/interfaces/user_window_controller.mojom
@@ -9,7 +9,7 @@ struct UserWindow {
   string window_title;
 };
 
-// An observer of user windows within mojom::CONTAINER_USER_WINDOWS.
+// An observer of user windows within mojom::Container::USER_WINDOWS.
 // TODO(msw): Observe focus changes, title/icon changes, etc.
 interface UserWindowObserver {
   // Called when the observer is first added to supply the initial state.
@@ -25,4 +25,4 @@ interface UserWindowObserver {
 interface UserWindowController {
   AddUserWindowObserver(UserWindowObserver observer);
   FocusUserWindow(uint32 window_id);
-};
+};