mash: Replace int ShelfIDs with AppLaunchID strings.

ash/public/cpp/shelf_types.h

Index: ash/public/cpp/shelf_types.h
diff --git a/ash/public/cpp/shelf_types.h b/ash/public/cpp/shelf_types.h
index 7f24ae401709990316f534b6029e5f3818ab9396..bf75287886f472b590955a9c8925acfb1e55c8dd 100644
--- a/ash/public/cpp/shelf_types.h
+++ b/ash/public/cpp/shelf_types.h
@@ -6,7 +6,9 @@
 #define ASH_PUBLIC_CPP_SHELF_TYPES_H_
 
 #include <cstdint>
+#include <string>

[msw, 2017/05/04 14:17:30]

self nit: removed

[James Cook, 2017/05/04 16:38:48]

Huh?

[msw, 2017/05/04 19:05:57]

Ha, sorry, I was up really late working on this and reviewing it myself. I
remove this unused include locally, but hadn't yet uploaded a revised patch set.

 
+#include "ash/public/cpp/app_launch_id.h"
 #include "ash/public/cpp/ash_public_export.h"
 
 namespace ash {
@@ -89,10 +91,8 @@ enum ShelfAction {
   SHELF_ACTION_APP_LIST_SHOWN,
 };
 
-// Shelf IDs are sequential values assigned to shelf items by ShelfModel for
-// runtime use; they are not persisted across restarts of the ash environment.
-using ShelfID = uint32_t;
-const ShelfID kInvalidShelfID = 0u;
+// TODO(msw): Rename AppLaunchId to ShelfID.
+using ShelfID = AppLaunchId;
 
 // The type of a shelf item.
 enum ShelfItemType {