Make sure channel-associated interface pointers are always safe to call.

mojo/public/cpp/bindings/tests/associated_interface_unittest.cc

 // 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.
 
 #include <stddef.h>
 #include <stdint.h>
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 1160 matching lines @@
   auto provider_provider = binding.CreateInterfacePtrAndBind();
   AssociatedPingProviderAssociatedPtr provider;
   provider_provider->GetPingProvider(mojo::MakeRequest(&provider));
   PingServiceAssociatedPtr ping;
   provider->GetPing(mojo::MakeRequest(&ping));
   base::RunLoop run_loop;
   ping.set_connection_error_handler(run_loop.QuitClosure());
   run_loop.Run();
 }
 
+TEST_F(AssociatedInterfaceTest, GetIsolatedInterface) {
+  IntegerSenderAssociatedPtr sender;
+  GetIsolatedInterface(MakeRequest(&sender).PassHandle());
+  sender->Send(42);
+}
+
 }  // namespace
 }  // namespace test
 }  // namespace mojo