Bug 2004669 - Missed hiding a private window option with policy. r=kcochrane,fxview-reviewers

Differential Revision: https://phabricator.services.mozilla.com/D277066

Author: mkaply

browser/components/firefoxview/history.mjs

@@ -18,6 +18,7 @@ const lazy = {};
 
 ChromeUtils.defineESModuleGetters(lazy, {
   HistoryController: "resource:///modules/HistoryController.sys.mjs",
+  PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
   ProfileAge: "resource://gre/modules/ProfileAge.sys.mjs",
 });
 
@@ -253,6 +254,7 @@ class HistoryInView extends ViewPage {
           @click=${this.openInNewPrivateWindow}
           data-l10n-id="fxviewtabrow-open-in-private-window"
           data-l10n-attrs="accesskey"
+          ?hidden=${!lazy.PrivateBrowsingUtils.enabled}
         ></panel-item>
         <hr />
         <panel-item