updating Analytics code for Google Optimize

I've thrown together a small module to add this in via a backend config for CE 1.9.3.x, hopefully it'll be useful to some.

appetcmodulesNamespace_Googleoptimize.xml

<?xml version="1.0"?>
<!--
/**
 * Class Namespace_Googleoptimize
 *
 * @category    Namespace
 * @package     Namespace_Googleoptimize
 */
-->
<config>
    <modules>
        <Namespace_Googleoptimize>
            <active>true</active>
            <codePool>local</codePool>
        </Namespace_Googleoptimize>
    </modules>
</config>

---

appcodelocalNamespaceGoogleoptimizeetcconfig.xml

<?xml version="1.0"?>
<!--
/**
* Namespace
*
* @category    Namespace
* @package     Namespace_Googleoptimize
*/
-->
<config>
    <modules>
        <Namespace_Googleoptimize>
            <version>0.1.0</version>
        </Namespace_Googleoptimize>
    </modules>
    <global>
        <helpers>
            <namespace_googleoptimize>
                <class>Namespace_Googleoptimize_Helper</class>
            </namespace_googleoptimize>
        </helpers>
        <blocks>
            <googleanalytics>
                <rewrite>
                    <ga>Namespace_Googleoptimize_Block_Ga</ga>
                </rewrite>
            </googleanalytics>
        </blocks>
    </global>
</config>

---

appcodelocalNamespaceGoogleoptimizeetcsystem.xml

<?xml version="1.0"?>
<config>
    <sections>
        <google translate="label" module="googleanalytics">
            <label>Google API</label>
            <tab>sales</tab>
            <frontend_type>text</frontend_type>
            <sort_order>340</sort_order>
            <show_in_default>1</show_in_default>
            <show_in_website>1</show_in_website>
            <show_in_store>1</show_in_store>
            <groups>
                <googleoptimize translate="label">
                    <label>Google Optimize</label>
                    <frontend_type>text</frontend_type>
                    <sort_order>20</sort_order>
                    <show_in_default>1</show_in_default>
                    <show_in_website>1</show_in_website>
                    <show_in_store>1</show_in_store>
                    <fields>
                        <active translate="label">
                            <label>Enable</label>
                            <frontend_type>select</frontend_type>
                            <source_model>adminhtml/system_config_source_yesno</source_model>
                            <sort_order>10</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>1</show_in_website>
                            <show_in_store>1</show_in_store>
                        </active>
                        <container translate="label">
                            <label>Container ID</label>
                            <frontend_type>text</frontend_type>
                            <sort_order>20</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>1</show_in_website>
                            <show_in_store>1</show_in_store>
                            <comment>Enter the full container ID, ie GTM-XXXXXXX</comment>
                        </container>
                    </fields>
                </googleoptimize>
            </groups>
        </google>
    </sections>
</config>

---

appcodelocalNamespaceGoogleoptimizeHelperData.php

<?php
/**
* Namespace
*
* @category    Namespace
* @package     Namespace_Googleoptimize
 */

class Namespace_Googleoptimize_Helper_Data extends Mage_Core_Helper_Abstract
{

    const XML_PATH_ACTIVE          = 'google/googleoptimize/active';
    const XML_PATH_CONTAINER       = 'google/googleoptimize/container';

     /**
     * Whether Google Optimize is enabled in backend
     *
     * @param mixed $store
     * @return bool
     */

    public function isGoogleOptimizeEnabled($store = null)
    {
        return Mage::getStoreConfigFlag(self::XML_PATH_ACTIVE, $store);
    }

    /**
     * Get Google Optimize Container ID
     *
     * @param string $store
     * @return string
     */
    public function getContainerId($store = null)
    {
        return Mage::getStoreConfig(self::XML_PATH_CONTAINER, $store);
    }


}

---

appcodelocalNamespaceGoogleoptimizeBlockGa.php

<?php
/**
* Namespace
*
* @category    Namespace
* @package     Namespace_Googleoptimize
 */

class Namespace_Googleoptimize_Block_Ga extends Mage_GoogleAnalytics_Block_Ga
{

    /**
     * Render regular page tracking javascript code
     * The custom "page name" may be set from layout or somewhere else. It must start from slash.
     *
     * @param string $accountId
     * @return string
     */
    protected function _getPageTrackingCodeUniversal($accountId)
    {

        if ($this->helper('namespace_googleoptimize')->isGoogleOptimizeEnabled()) {
            $containerId = $this->helper('namespace_googleoptimize')->getContainerId();
            return "
ga('create', '{$this->jsQuoteEscape($accountId)}', 'auto');
" . $this->_getAnonymizationCode() . "
ga('require', '{$containerId}');
ga('send', 'pageview');
";

        } else {
            return "
ga('create', '{$this->jsQuoteEscape($accountId)}', 'auto');
" . $this->_getAnonymizationCode() . "
ga('send', 'pageview');
";
        }



    }


    /**
     * Is Googel Optimize Enabled
     *
     * @return bool
     */
    protected function _isEnabled()
    {
        return Mage::helper('namespace_googleoptimize')->isGoogleOptimizeEnabled();
    }


}

---

It's worth noting that this might be the route required for you even if you are using Tag Manager.

Despite the fact that Tag Manager has a default tag for Google Optimize built in, their own docs say;

While it’s possible to deploy the Optimize plugin via Google Tag Manager, it will often result in significantly increased latency

https://support.google.com/360suite/optimize/answer/7359264?hl=en

And they are not kidding. I was running an extremely basic test and this resulted in a very long lag before the site was rendered, as I used the JS that prevents the FOUC.

See backend here config;