Remove use of std::function from Mojo internals

mojo/edk/system/data_pipe_producer_dispatcher.cc

 // Copyright 2013 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/edk/system/data_pipe_producer_dispatcher.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 486 matching lines @@
 
   ports::PortStatus port_status;
   int rv = node_controller_->node()->GetStatus(control_port_, &port_status);
   if (rv != ports::OK || !port_status.receiving_messages) {
     DVLOG(1) << "Data pipe producer " << pipe_id_ << " is aware of peer closure"
              << " [control_port=" << control_port_.name() << "]";
     peer_closed_ = true;
   } else if (rv == ports::OK && port_status.has_messages && !in_transit_) {
     ports::ScopedMessage message;
     do {
-      int rv = node_controller_->node()->GetMessageIf(control_port_, nullptr,
-                                                      &message);
+      int rv = node_controller_->node()->GetMessage(
+          control_port_, &message, nullptr);
       if (rv != ports::OK)
         peer_closed_ = true;
       if (message) {
         if (message->num_payload_bytes() < sizeof(DataPipeControlMessage)) {
           peer_closed_ = true;
           break;
         }
 
         const DataPipeControlMessage* m =
             static_cast<const DataPipeControlMessage*>(
@@ skipping 21 matching lines @@
   }
 
   if (peer_closed_ != was_peer_closed ||
       available_capacity_ != previous_capacity) {
     awakable_list_.AwakeForStateChange(GetHandleSignalsStateNoLock());
   }
 }
 
 }  // namespace edk
 }  // namespace mojo