Support custom message filtering on Mojo binding objects

mojo/public/interfaces/bindings/tests/test_associated_interfaces.mojom

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module mojo.test;
 
+import "mojo/public/interfaces/bindings/tests/ping_service.mojom";
+
 interface FooInterface {};
 
 struct StructContainsAssociated {
   associated FooInterface? foo_interface;
   associated FooInterface& foo_request;
   array<associated FooInterface> foo_interfaces;
   array<associated FooInterface&> foo_requests;
 };
 
 union UnionContainsAssociated {
@@ skipping 18 matching lines @@
 
 interface IntegerSender {
   Echo(int32 value) => (int32 value);
   Send(int32 value);
 };
 
 interface IntegerSenderConnection {
   GetSender(associated IntegerSender& sender);
   AsyncGetSender() => (associated IntegerSender sender);
 };
+
+interface AssociatedPingProvider {
+  GetPing(associated PingService& request);
+};