Mojo C++ bindings: Remove more use_new_wrapper_types=false.

components/safe_json/safe_json_parser_impl.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 "components/safe_json/safe_json_parser_impl.h"
 
 #include "base/callback.h"
 #include "base/sequenced_task_runner.h"
 #include "base/threading/sequenced_task_runner_handle.h"
 #include "base/values.h"
@@ skipping 43 matching lines @@
 
   // Shut down the utility process.
   mojo_json_parser_.reset();
 
   caller_task_runner_->PostTask(
       FROM_HERE, base::Bind(&SafeJsonParserImpl::ReportResults,
                             base::Unretained(this), nullptr, "Json error"));
 }
 
 void SafeJsonParserImpl::OnParseDone(const base::ListValue& wrapper,
-                                     mojo::String error) {
+                                     const base::Optional<std::string>& error) {
   DCHECK(io_thread_checker_.CalledOnValidThread());
 
   // Shut down the utility process.
   mojo_json_parser_.reset();
 
   std::unique_ptr<base::Value> parsed_json;
   std::string error_message;
   if (!wrapper.empty()) {
     const base::Value* value = nullptr;
     CHECK(wrapper.Get(0, &value));
     parsed_json.reset(value->DeepCopy());
-  } else {
-    error_message = error.get();
+  } else if (error.has_value()) {
+    error_message = *error;

[blundell, 2016/11/08 08:32:41]

tiny nit: I think it would be nicer to use |error.value()| here.

[yzshen1, 2016/11/09 17:13:22]

Done.

   }
 
   // Call ReportResults() on caller's thread.
   caller_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&SafeJsonParserImpl::ReportResults, base::Unretained(this),
                  base::Passed(&parsed_json), error_message));
 }
 
 void SafeJsonParserImpl::ReportResults(std::unique_ptr<base::Value> parsed_json,
                                        const std::string& error) {
   DCHECK(caller_task_runner_->RunsTasksOnCurrentThread());
   if (error.empty() && parsed_json) {
     if (!success_callback_.is_null())
       success_callback_.Run(std::move(parsed_json));
   } else {
     if (!error_callback_.is_null())
       error_callback_.Run(error);
   }
 
   // The parsing is done whether an error occured or not, so this instance can
   // be cleaned up.
   delete this;
 }
 
 }  // namespace safe_json