mash: Move shelf model and item classes to ash/common/shelf

ash/common/shelf/shelf_model.h

Index: ash/common/shelf/shelf_model.h
diff --git a/ash/shelf/shelf_model.h b/ash/common/shelf/shelf_model.h
similarity index 94%
rename from ash/shelf/shelf_model.h
rename to ash/common/shelf/shelf_model.h
index 1f29124dd158dab318ebe5d49a1040f91b3ed136..deeffac9d7ad21ff4202b904aa8d875ac74ce3f2 100644
--- a/ash/shelf/shelf_model.h
+++ b/ash/common/shelf/shelf_model.h
@@ -2,11 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef ASH_SHELF_SHELF_MODEL_H_
-#define ASH_SHELF_SHELF_MODEL_H_
+#ifndef ASH_COMMON_SHELF_SHELF_MODEL_H_
+#define ASH_COMMON_SHELF_SHELF_MODEL_H_
 
 #include "ash/ash_export.h"
-#include "ash/shelf/shelf_item_types.h"
+#include "ash/common/shelf/shelf_item_types.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 
@@ -98,4 +98,4 @@ class ASH_EXPORT ShelfModel {
 
 }  // namespace ash
 
-#endif  // ASH_SHELF_SHELF_MODEL_H_
+#endif  // ASH_COMMON_SHELF_SHELF_MODEL_H_