Use string for Signatures protobuf. am: 9b2f178969 am: 0730ba3059
am: 38ab8025aa

Change-Id: I83da4e8eb7c833a157b1a052da6632d08f790704
diff --git a/Android.bp b/Android.bp
index dac1acd..fef664e 100644
--- a/Android.bp
+++ b/Android.bp
@@ -724,3 +724,12 @@
         },
     },
 }
+
+// AIDL interface between libupdate_engine and the Things jar.
+filegroup {
+    name: "things_update_engine_aidl",
+    srcs: [
+        "binder_bindings/android/brillo/IUpdateEngine.aidl",
+        "binder_bindings/android/brillo/IUpdateEngineStatusCallback.aidl",
+    ],
+}