Switch base::Value typemapping to be by value instead of by unique_ptr.

components/safe_json/utility/safe_json_parser_mojo_impl.cc

 // 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.
 
 #include "components/safe_json/utility/safe_json_parser_mojo_impl.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/json/json_reader.h"
@@ skipping 14 matching lines @@
                           std::move(request));
 }
 
 void SafeJsonParserMojoImpl::Parse(const std::string& json,
                                    const ParseCallback& callback) {
   int error_code;
   std::string error;
   std::unique_ptr<base::Value> value = base::JSONReader::ReadAndReturnError(
       json, base::JSON_PARSE_RFC, &error_code, &error);
   if (value) {
-    callback.Run(std::move(value), base::nullopt);
+    callback.Run(*value, base::nullopt);
   } else {
-    callback.Run(nullptr, base::make_optional(std::move(error)));
+    callback.Run(base::nullopt, base::make_optional(std::move(error)));
   }
 }
 
 }  // namespace safe_json