Bug 1574255 - Removed gUsageRequest from pageinfo's permissions.js. r=johannh

Differential Revision: https://phabricator.services.mozilla.com/D42687

--HG--
extra : moz-landing-system : lando

browser/base/content/pageinfo/permissions.js

@@ -9,7 +9,6 @@ const { SitePermissions } = ChromeUtils.import(
 );
 
 var gPermPrincipal;
-var gUsageRequest;
 
 // Array of permissionIDs sorted alphabetically by label.
 var gPermissions = SitePermissions.listPermissions()
@@ -54,11 +53,6 @@ function onLoadPermission(uri, principal) {
 
 function onUnloadPermission() {
   Services.obs.removeObserver(permissionObserver, "perm-changed");
-
-  if (gUsageRequest) {
-    gUsageRequest.cancel();
-    gUsageRequest = null;
-  }
 }
 
 function initRow(aPartId) {