<?php
namespace Application\Block\GoogleMap;
use Concrete\Block\GoogleMap\Controller as GoogleMapBlockController;
use Loader;
use Page;
class Controller extends GoogleMapBlockController{
    public function registerViewAssets($outputContent = '')
    {
        $this->requireAsset('javascript', 'jquery');
        $c = Page::getCurrentPage();
        if (!$c->isEditMode()) {
        $this->addFooterItem(
            '<script defer src="https://maps.googleapis.com/maps/api/js"></script>'
        );
        }

$this->addFooterItem(
   '<script defer src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY"></script>'
   );