Control the visibility of the extension attribution on the New Tab page

This policy determines whether an attribution to the extension modifying the New Tab Page (NTP) is displayed in the NTP's footer. By default, if an extension has overridden the standard NTP, a message attributing this change to the specific extension will appear in the footer. This attribution typically includes a link to the relevant extension in the Chrome Web Store. If this policy is left unset or set to true, the extension attribution will be visible on the NTP footer when an extension is controlling the NTP. If this policy is set to false, the attribution to the extension in the NTP footer will be suppressed.