Mojo C++ bindings: support disconnect with a reason.

mojo/public/cpp/bindings/lib/control_message_handler.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/lib/control_message_handler.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <utility>
 
@@ skipping 123 matching lines @@
   interface_control::internal::RunOrClosePipeMessageParams_Data* params =
       reinterpret_cast<
           interface_control::internal::RunOrClosePipeMessageParams_Data*>(
           message->mutable_payload());
   interface_control::RunOrClosePipeMessageParamsPtr params_ptr;
   Deserialize<interface_control::RunOrClosePipeMessageParamsDataView>(
       params, &params_ptr, &context_);
   auto& input = *params_ptr->input;
   if (input.is_require_version())
     return interface_version_ >= input.get_require_version()->version;
+  else if (input.is_send_disconnect_reason()) {
+    disconnect_custom_reason_ =
+        input.get_send_disconnect_reason()->custom_reason;
+    disconnect_description_ =
+        std::move(input.get_send_disconnect_reason()->description);
+    return true;
+  }
 
   return false;
 }
 
 }  // namespace internal
 }  // namespace mojo