Make extension callbacks with auto-dismissing dialogs

components/app_modal/javascript_dialog_manager.cc

Index: components/app_modal/javascript_dialog_manager.cc
diff --git a/components/app_modal/javascript_dialog_manager.cc b/components/app_modal/javascript_dialog_manager.cc
index c5a368384b597f56c031f3c1ad1c6b89f659e268..560b1144af62e1aeca83d2ccc2d4ebdc9b2bf70d 100644
--- a/components/app_modal/javascript_dialog_manager.cc
+++ b/components/app_modal/javascript_dialog_manager.cc
@@ -85,6 +85,11 @@ void JavaScriptDialogManager::SetExtensionsClient(
   extensions_client_ = std::move(extensions_client);
 }
 
+JavaScriptDialogExtensionsClient*
+JavaScriptDialogManager::GetExtensionsClient() {
+  return extensions_client_.get();
+}
+
 JavaScriptDialogManager::JavaScriptDialogManager()
     : extensions_client_(new DefaultExtensionsClient) {
 }