Support additional mash shelf alignments.

mash/shelf/public/interfaces/shelf.mojom

Index: mash/shelf/public/interfaces/shelf.mojom
diff --git a/mash/shelf/public/interfaces/shelf.mojom b/mash/shelf/public/interfaces/shelf.mojom
index befe2a61635af06989402bddff515a3a3343853a..3e7887b271606d4ad449b5772796f31931ed496b 100644
--- a/mash/shelf/public/interfaces/shelf.mojom
+++ b/mash/shelf/public/interfaces/shelf.mojom
@@ -4,6 +4,7 @@
 
 module mash.shelf.mojom;
 
+import "mash/shelf/public/interfaces/shelf_constants.mojom";
 import "skia/public/interfaces/bitmap.mojom";
 
 // TODO(msw): Add support for multiple displays (with unified and multi-shelf).
@@ -39,12 +40,6 @@ interface ShelfItemDelegate {
   ItemReordered(uint32 order);
 };
 
-// These values match ash::ShelfAlignment.
-enum Alignment { BOTTOM, LEFT, RIGHT, };
-
-// These values match ash::ShelfAutoHideBehavior.
-enum AutoHideBehavior { ALWAYS, NEVER, HIDDEN, };
-
 // ContextMenuItems may be used to supplement ash shelf item context menus.
 struct ContextMenuItem {
   enum Type { ITEM, CHECK, RADIO, SEPARATOR, SUBMENU };