Use OnceCallback for Mojo binding connection error handlers.

mojo/public/cpp/bindings/connection_error_callback.h

 // Copyright 2016 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.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_CONNECTION_ERROR_CALLBACK_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_CONNECTION_ERROR_CALLBACK_H_
 
 #include "base/callback.h"
 
 namespace mojo {
 
-// This callback type accepts user-defined disconnect reason and description. If
-// the other side specifies a reason on closing the connection, it will be
+// These callback types accept user-defined disconnect reason and description.
+// If the other side specifies a reason on closing the connection, it will be
 // passed to the error handler.
 using ConnectionErrorWithReasonCallback =
-    base::Callback<void(uint32_t /* custom_reason */,
-                        const std::string& /* description */)>;
+    base::OnceCallback<void(uint32_t /* custom_reason */,
+                            const std::string& /* description */)>;
+using RepeatingConnectionErrorWithReasonCallback =
+    base::RepeatingCallback<void(uint32_t /* custom_reason */,
+                                 const std::string& /* description */)>;
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_CONNECTION_ERROR_CALLBACK_H_