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

components/safe_json/safe_json_parser_impl.cc

Index: components/safe_json/safe_json_parser_impl.cc
diff --git a/components/safe_json/safe_json_parser_impl.cc b/components/safe_json/safe_json_parser_impl.cc
index 8f0ea483ed9a37e35c318e9c453ca69d9e932d0c..7a988d3d6e93cb56eb968f37b9482507e7006ad2 100644
--- a/components/safe_json/safe_json_parser_impl.cc
+++ b/components/safe_json/safe_json_parser_impl.cc
@@ -61,7 +61,7 @@ void SafeJsonParserImpl::OnConnectionError() {
                  nullptr, "Connection error with the json parser process."));
 }
 
-void SafeJsonParserImpl::OnParseDone(std::unique_ptr<base::Value> result,
+void SafeJsonParserImpl::OnParseDone(const base::Optional<base::Value>& result,
                                      const base::Optional<std::string>& error) {
   DCHECK(io_thread_checker_.CalledOnValidThread());
 
@@ -72,7 +72,8 @@ void SafeJsonParserImpl::OnParseDone(std::unique_ptr<base::Value> result,
   caller_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&SafeJsonParserImpl::ReportResults, base::Unretained(this),
-                 base::Passed(&result), error.value_or("")));
+                 base::Passed(result ? result->CreateDeepCopy() : nullptr),
+                 error.value_or("")));
 }
 
 void SafeJsonParserImpl::ReportResults(std::unique_ptr<base::Value> parsed_json,