[input][fidl] Make InputDevice discoverable

Bug: 103199

Change-Id: I02fadf560d5f2d5ff488c6b770c6147a8bdc0f9f
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/693422
Commit-Queue: Ruby Zhuang <rdzhuang@google.com>
API-Review: Jocelyn Dang <jocelyndang@google.com>
Reviewed-by: David Gilhooley <dgilhooley@google.com>
Reviewed-by: Jocelyn Dang <jocelyndang@google.com>
diff --git a/sdk/fidl/fuchsia.input.report/device.fidl b/sdk/fidl/fuchsia.input.report/device.fidl
index ed47442..d2ec4c4 100644
--- a/sdk/fidl/fuchsia.input.report/device.fidl
+++ b/sdk/fidl/fuchsia.input.report/device.fidl
@@ -36,6 +36,7 @@
 /// reports for each client that connects. Reports are removed from the FIFO
 /// once they are read by the client. If the FIFO is full, it will drop the
 /// oldest report to make room for an incoming report.
+@discoverable
 protocol InputDevice {
     /// Open a new InputReportsReader on this device. Each reader receives
     /// their own reports.