Firefox overlay is seen opened even if Import Overlay is Cancelled.

chrome/browser/ui/webui/settings/settings_import_data_handler.cc

Index: chrome/browser/ui/webui/settings/settings_import_data_handler.cc
diff --git a/chrome/browser/ui/webui/settings/settings_import_data_handler.cc b/chrome/browser/ui/webui/settings/settings_import_data_handler.cc
index 89b54a9f4af63d2a8e6ece3e6907156564f5cfe1..a7f4925faa9214cc6e2dcef95e1fdfbc9ebe781d 100644
--- a/chrome/browser/ui/webui/settings/settings_import_data_handler.cc
+++ b/chrome/browser/ui/webui/settings/settings_import_data_handler.cc
@@ -70,6 +70,9 @@ void ImportDataHandler::RegisterMessages() {
       "importFromBookmarksFile",
       base::Bind(&ImportDataHandler::HandleChooseBookmarksFile,
                  base::Unretained(this)));
+  web_ui()->RegisterMessageCallback(
+      "closeImportLockDialog",
+      base::Bind(&ImportDataHandler::Close, base::Unretained(this)));
 }
 
 void ImportDataHandler::OnJavascriptDisallowed() {
@@ -142,6 +145,10 @@ void ImportDataHandler::ImportData(const base::ListValue* args) {
   }
 }
 
+void ImportDataHandler::Close(const base::ListValue* args) {
+  if (importer_host_)
+    importer_host_->NotifyImportEnded();
+}
 void ImportDataHandler::InitializeDialog(const base::ListValue* args) {
   AllowJavascript();