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

chrome/browser/importer/external_process_importer_client.cc

Index: chrome/browser/importer/external_process_importer_client.cc
diff --git a/chrome/browser/importer/external_process_importer_client.cc b/chrome/browser/importer/external_process_importer_client.cc
index 7c9a4064a5d4ed1c921929d51a12503b1cbe5e75..28528d2bfb35d3cac792bf0ba843467c182b8ed7 100644
--- a/chrome/browser/importer/external_process_importer_client.cc
+++ b/chrome/browser/importer/external_process_importer_client.cc
@@ -80,8 +80,7 @@ void ExternalProcessImporterClient::Start() {
   // If the utility process hasn't started yet the message will queue until it
   // does.
   auto observer_ptr = binding_.CreateInterfacePtrAndBind();
-  profile_import_->StartImport(source_profile_, items_,
-                               std::move(localized_strings),
+  profile_import_->StartImport(source_profile_, items_, *localized_strings,
                                std::move(observer_ptr));
 }