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

ash/common/shelf/shelf_model.cc

Index: ash/common/shelf/shelf_model.cc
diff --git a/ash/shelf/shelf_model.cc b/ash/common/shelf/shelf_model.cc
similarity index 98%
rename from ash/shelf/shelf_model.cc
rename to ash/common/shelf/shelf_model.cc
index 4f00683d79f58c35aedfb1d61e85dedf37492e4a..a8094707245bfd76e1cf81da2db7fa91330a2947 100644
--- a/ash/shelf/shelf_model.cc
+++ b/ash/common/shelf/shelf_model.cc
@@ -2,12 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ash/shelf/shelf_model.h"
+#include "ash/common/shelf/shelf_model.h"
 
 #include <algorithm>
 
-#include "ash/ash_switches.h"
-#include "ash/shelf/shelf_model_observer.h"
+#include "ash/common/shelf/shelf_model_observer.h"
 
 namespace ash {