mash: Port ash_sysui ShelfDelegateMus impl to mojo:ash.

mash/shelf/public/interfaces/shelf_constants.mojom

Index: mash/shelf/public/interfaces/shelf_constants.mojom
diff --git a/mash/shelf/public/interfaces/shelf_constants.mojom b/mash/shelf/public/interfaces/shelf_constants.mojom
deleted file mode 100644
index bc7ca9552075c5b0346a3c5aff3a9350fc3817a0..0000000000000000000000000000000000000000
--- a/mash/shelf/public/interfaces/shelf_constants.mojom
+++ /dev/null
@@ -1,11 +0,0 @@
-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-module mash.shelf.mojom;
-
-// These values match ash::wm::ShelfAlignment.
-enum Alignment { BOTTOM, LEFT, RIGHT, };
-
-// These values match ash::ShelfAutoHideBehavior.
-enum AutoHideBehavior { ALWAYS, NEVER, HIDDEN, };