Mojo C++ bindings: add more perf tests for Router/MultiplexRouter.

mojo/public/cpp/bindings/lib/interface_endpoint_client.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 "mojo/public/cpp/bindings/interface_endpoint_client.h"
 
 #include <stdint.h>
 
 #include <utility>
 
@@ skipping 134 matching lines @@
       encountered_error_(false),
       task_runner_(std::move(runner)),
       control_message_proxy_(this),
       control_message_handler_(interface_version),
       weak_ptr_factory_(this) {
   DCHECK(handle_.is_valid());
   DCHECK(handle_.is_local());
 
   // TODO(yzshen): the way to use validator (or message filter in general)
   // directly is a little awkward.
-  filters_.Append(std::move(payload_validator));
+  if (payload_validator)
+    filters_.Append(std::move(payload_validator));
 
   controller_ = handle_.group_controller()->AttachEndpointClient(
       handle_, this, task_runner_);
   if (expect_sync_requests)
     controller_->AllowWokenUpBySyncWatchOnSameThread();
 }
 
 InterfaceEndpointClient::~InterfaceEndpointClient() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
@@ skipping 163 matching lines @@
     return responder->Accept(message);
   } else {
     if (mojo::internal::ControlMessageHandler::IsControlMessage(message))
       return control_message_handler_.Accept(message);
 
     return incoming_receiver_->Accept(message);
   }
 }
 
 }  // namespace mojo