function _openUserKeyMap() {
        var userKeyMapPath = _getUserKeyMapFilePath(),
            file = FileSystem.getFileForPath(userKeyMapPath);
        file.exists(function (err, doesExist) {
            if (doesExist) {
                CommandManager.execute(Commands.FILE_OPEN, { fullPath: userKeyMapPath });
            } else {
                var defaultContent = "{\n    \"documentation\": \"https://github.com/adobe/brackets/wiki/User-Key-Bindings\"," +
                                     "\n    \"overrides\": {" +
                                     "\n        \n    }\n}\n";

                FileUtils.writeText(file, defaultContent, true)
                    .done(function () {
                        CommandManager.execute(Commands.FILE_OPEN, { fullPath: userKeyMapPath });
                    });
            }
        });
    }
@private

Opens the existing key map file or creates a new one with default content
if it does not exist.