Mojo C++ Bindings: Additional support for associated binding sets

mojo/public/cpp/bindings/associated_interface_ptr.h

Index: mojo/public/cpp/bindings/associated_interface_ptr.h
diff --git a/mojo/public/cpp/bindings/associated_interface_ptr.h b/mojo/public/cpp/bindings/associated_interface_ptr.h
index e8e455ae3cc9e6df81099fc0c552d2c076a9f6f2..70ee75e9ab7e12d2713597aa4b85df014c6ee232 100644
--- a/mojo/public/cpp/bindings/associated_interface_ptr.h
+++ b/mojo/public/cpp/bindings/associated_interface_ptr.h
@@ -18,6 +18,8 @@
 #include "mojo/public/cpp/bindings/associated_interface_ptr_info.h"
 #include "mojo/public/cpp/bindings/associated_interface_request.h"
 #include "mojo/public/cpp/bindings/lib/associated_interface_ptr_state.h"
+#include "mojo/public/cpp/bindings/lib/multiplex_router.h"
+#include "mojo/public/cpp/system/message_pipe.h"
 
 namespace mojo {
 
@@ -209,6 +211,17 @@ AssociatedInterfaceRequest<Interface> GetProxy(
   return request;
 }
 
+// Creates an associated interface proxy which casts its messages into the void.
+template <typename Interface>
+void GetDummyProxyForTesting(AssociatedInterfacePtr<Interface>* proxy) {
+  MessagePipe pipe;
+  scoped_refptr<internal::MultiplexRouter> router =
+      new internal::MultiplexRouter(false, std::move(pipe.handle0),
+                                    base::ThreadTaskRunnerHandle::Get());
+  std::unique_ptr<AssociatedGroup> group = router->CreateAssociatedGroup();
+  GetProxy(proxy, group.get());
+}
+
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_INTERFACE_PTR_H_