[autofill] Sync server card and address metadata.

sync/internal_api/public/base/model_type.h

Index: sync/internal_api/public/base/model_type.h
diff --git a/sync/internal_api/public/base/model_type.h b/sync/internal_api/public/base/model_type.h
index 06391810c746c10060cceda23e123720d5882d0e..b07f80de6fa0261c2d1e337ac7a265085ede9bbb 100644
--- a/sync/internal_api/public/base/model_type.h
+++ b/sync/internal_api/public/base/model_type.h
@@ -67,6 +67,9 @@ enum ModelType {
   // Credit cards and addresses synced from the user's account. These are
   // read-only on the client.
   AUTOFILL_WALLET_DATA,
+  // Usage counts and last use dates for Wallet cards and addresses. This data
+  // is both readable and writable.
+  AUTOFILL_WALLET_METADATA,
   // A themes object.
   THEMES,
   // A typed_url object.