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

ash/public/interfaces/shelf.typemap

Index: ash/public/interfaces/shelf.typemap
diff --git a/ash/public/interfaces/shelf.typemap b/ash/public/interfaces/shelf.typemap
index 96e016d2d5ed2365e1bc52c464a8da6f3513d553..4be71eb21ce4a95d5ed43268905dd333907bec53 100644
--- a/ash/public/interfaces/shelf.typemap
+++ b/ash/public/interfaces/shelf.typemap
@@ -3,11 +3,20 @@
 # found in the LICENSE file.
 
 mojom = "//ash/public/interfaces/shelf.mojom"
-public_headers = [ "//ash/public/cpp/shelf_types.h" ]
+public_headers = [
+  "//ash/public/cpp/shelf_item.h",
+  "//ash/public/cpp/shelf_types.h",
+]
 traits_headers = [ "//ash/public/interfaces/shelf_struct_traits.h" ]
+sources = [
+  "shelf_struct_traits.cc",
+]
 type_mappings = [
   "ash.mojom.ShelfAction=ash::ShelfAction",
   "ash.mojom.ShelfAlignment=ash::ShelfAlignment",
   "ash.mojom.ShelfAutoHideBehavior=ash::ShelfAutoHideBehavior",
+  "ash.mojom.ShelfItem=ash::ShelfItem",
+  "ash.mojom.ShelfItemStatus=ash::ShelfItemStatus",
+  "ash.mojom.ShelfItemType=ash::ShelfItemType",
   "ash.mojom.ShelfLaunchSource=ash::ShelfLaunchSource",
 ]