mash: Fix ShelfItem mojo struct; add enums and traits.

ash/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 import("//ui/base/ui_features.gni")
 
 # Historical note: Ash shipped on Windows for a couple years to support
@@ skipping 146 matching lines @@
     "common/shelf/shelf_background_animator_observer.h",
     "common/shelf/shelf_button.cc",
     "common/shelf/shelf_button.h",
     "common/shelf/shelf_button_pressed_metric_tracker.cc",
     "common/shelf/shelf_button_pressed_metric_tracker.h",
     "common/shelf/shelf_constants.cc",
     "common/shelf/shelf_constants.h",
     "common/shelf/shelf_controller.cc",
     "common/shelf/shelf_controller.h",
     "common/shelf/shelf_delegate.h",
-    "common/shelf/shelf_item_types.cc",
-    "common/shelf/shelf_item_types.h",
     "common/shelf/shelf_layout_manager.cc",
     "common/shelf/shelf_layout_manager.h",
     "common/shelf/shelf_layout_manager_observer.h",
     "common/shelf/shelf_locking_manager.cc",
     "common/shelf/shelf_locking_manager.h",
     "common/shelf/shelf_model.cc",
     "common/shelf/shelf_model.h",
     "common/shelf/shelf_model_observer.h",
     "common/shelf/shelf_tooltip_manager.cc",
     "common/shelf/shelf_tooltip_manager.h",
@@ skipping 1328 matching lines @@
     "//content/public/app:both",
     "//device/bluetooth",
   ]
 
   data_deps = [
     "//ash/strings:ash_test_strings",
     "//ash/resources:ash_test_resources_with_content_100_percent",
     "//ash/resources:ash_test_resources_200_percent",
   ]
 }