--- a/toolkit/components/extensions/Extension.jsm
+++ b/toolkit/components/extensions/Extension.jsm
@@ -36,20 +36,16 @@ const Cc = Components.classes;
 const Cu = Components.utils;
 const Cr = Components.results;
 
 Cu.importGlobalProperties(["TextEncoder"]);
 
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/Services.jsm");
 
-/* globals processCount */
-
-XPCOMUtils.defineLazyPreferenceGetter(this, "processCount", "dom.ipc.processCount.extension");
-
 XPCOMUtils.defineLazyModuleGetters(this, {
   AddonManager: "resource://gre/modules/AddonManager.jsm",
   AddonManagerPrivate: "resource://gre/modules/AddonManager.jsm",
   AsyncShutdown: "resource://gre/modules/AsyncShutdown.jsm",
   ExtensionCommon: "resource://gre/modules/ExtensionCommon.jsm",
   ExtensionPermissions: "resource://gre/modules/ExtensionPermissions.jsm",
   ExtensionStorage: "resource://gre/modules/ExtensionStorage.jsm",
   ExtensionTestCommon: "resource://testing-common/ExtensionTestCommon.jsm",
@@ -70,16 +66,17 @@ XPCOMUtils.defineLazyGetter(
 Cu.import("resource://gre/modules/ExtensionParent.jsm");
 Cu.import("resource://gre/modules/ExtensionUtils.jsm");
 
 XPCOMUtils.defineLazyServiceGetters(this, {
   aomStartup: ["@mozilla.org/addons/addon-manager-startup;1", "amIAddonManagerStartup"],
   uuidGen: ["@mozilla.org/uuid-generator;1", "nsIUUIDGenerator"],
 });
 
+XPCOMUtils.defineLazyPreferenceGetter(this, "processCount", "dom.ipc.processCount.extension");
 XPCOMUtils.defineLazyPreferenceGetter(this, "useRemoteWebExtensions",
                                       "extensions.webextensions.remote", false);
 
 var {
   GlobalManager,
   ParentAPIManager,
   StartupCache,
   apiManager: Management,
@@ -226,18 +223,16 @@ function getExtensionUUID(id) {
 // For extensions that have called setUninstallURL(), send an event
 // so the browser can display the URL.
 var UninstallObserver = {
   initialized: false,
 
   init() {
     if (!this.initialized) {
       AddonManager.addAddonListener(this);
-      XPCOMUtils.defineLazyPreferenceGetter(this, "leaveStorage", LEAVE_STORAGE_PREF, false);
-      XPCOMUtils.defineLazyPreferenceGetter(this, "leaveUuid", LEAVE_UUID_PREF, false);
       this.initialized = true;
     }
   },
 
   onUninstalling(addon) {
     let extension = GlobalManager.extensionMap.get(addon.id);
     if (extension) {
       // Let any other interested listeners respond
@@ -247,17 +242,17 @@ var UninstallObserver = {
   },
 
   onUninstalled(addon) {
     let uuid = UUIDMap.get(addon.id, false);
     if (!uuid) {
       return;
     }
 
-    if (!this.leaveStorage) {
+    if (!Services.prefs.getBoolPref(LEAVE_STORAGE_PREF, false)) {
       // Clear browser.local.storage
       AsyncShutdown.profileChangeTeardown.addBlocker(
         `Clear Extension Storage ${addon.id}`,
         ExtensionStorage.clear(addon.id));
 
       // Clear any IndexedDB storage created by the extension
       let baseURI = Services.io.newURI(`moz-extension://${uuid}/`);
       let principal = Services.scriptSecurityManager.createCodebasePrincipal(
@@ -272,17 +267,17 @@ var UninstallObserver = {
 
       // Remove any permissions related to the unlimitedStorage permission
       // if we are also removing all the data stored by the extension.
       Services.perms.removeFromPrincipal(principal, "WebExtensions-unlimitedStorage");
       Services.perms.removeFromPrincipal(principal, "indexedDB");
       Services.perms.removeFromPrincipal(principal, "persistent-storage");
     }
 
-    if (!this.leaveUuid) {
+    if (!Services.prefs.getBoolPref(LEAVE_UUID_PREF, false)) {
       // Clear the entry in the UUID map
       UUIDMap.remove(addon.id);
     }
   },
 };
 
 UninstallObserver.init();