diff --git a/browser/base/content/browser-compacttheme.js b/browser/base/content/browser-compacttheme.js
index ba4169e987ab..38c05b85755b 100644
--- a/browser/base/content/browser-compacttheme.js
+++ b/browser/base/content/browser-compacttheme.js
@@ -25,11 +25,13 @@ var CompactTheme = {
     return this.styleSheet && !this.styleSheet.disabled;
   },
 
+  isCompactTheme(theme) {
+    return theme && (theme.id == "firefox-compact-dark@mozilla.org" ||
+                     theme.id == "firefox-compact-light@mozilla.org");
+  },
+
   get isThemeCurrentlyApplied() {
-    let theme = LightweightThemeManager.currentThemeWithPersistedData;
-    return theme && (
-           theme.id == "firefox-compact-dark@mozilla.org" ||
-           theme.id == "firefox-compact-light@mozilla.org");
+    return this.isCompactTheme(LightweightThemeManager.currentThemeWithFallback);
   },
 
   init() {
@@ -43,9 +45,7 @@ var CompactTheme = {
   observe(subject, topic, data) {
     if (topic == "lightweight-theme-styling-update") {
       let { theme } = JSON.parse(data) || {};
-      if (theme && (
-          theme.id == "firefox-compact-light@mozilla.org" ||
-          theme.id == "firefox-compact-dark@mozilla.org")) {
+      if (this.isCompactTheme(theme)) {
         // We are using the theme ID on this object instead of always referencing
         // LightweightThemeManager.currentTheme in case this is a preview
         this._toggleStyleSheet(true);
diff --git a/toolkit/mozapps/extensions/LightweightThemeManager.jsm b/toolkit/mozapps/extensions/LightweightThemeManager.jsm
index 4af8cda7ee6c..884f2fec4c47 100644
--- a/toolkit/mozapps/extensions/LightweightThemeManager.jsm
+++ b/toolkit/mozapps/extensions/LightweightThemeManager.jsm
@@ -6,13 +6,8 @@
 
 var EXPORTED_SYMBOLS = ["LightweightThemeManager"];
 
-ChromeUtils.defineModuleGetter(this, "LightweightThemePersister",
-  "resource://gre/modules/addons/LightweightThemePersister.jsm");
 ChromeUtils.defineModuleGetter(this, "LightweightThemeImageOptimizer",
   "resource://gre/modules/addons/LightweightThemeImageOptimizer.jsm");
-ChromeUtils.defineModuleGetter(this, "AppConstants",
-  "resource://gre/modules/AppConstants.jsm");
-
 
 // Holds optional fallback theme data that will be returned when no data for an
 // active theme can be found. This the case for WebExtension Themes, for example.
@@ -22,10 +17,7 @@ var LightweightThemeManager = {
   set fallbackThemeData(data) {
     if (data && Object.getOwnPropertyNames(data).length) {
       _fallbackThemeData = Object.assign({}, data);
-      if (LightweightThemePersister.persistEnabled) {
-        LightweightThemeImageOptimizer.purge();
-        _persistImages(_fallbackThemeData, () => {});
-      }
+      LightweightThemeImageOptimizer.purge();
     } else {
       _fallbackThemeData = null;
     }
@@ -43,24 +35,6 @@ var LightweightThemeManager = {
     return _fallbackThemeData;
   },
 
-  /*
-   * Returns the currently active theme, taking the fallback theme into account
-   * if we'd be using the default theme otherwise.
-   *
-   * This will rewrite the theme data to use locally persisted resources if
-   * available.
-   *
-   * Unless you have any special requirements, this is what you normally want
-   * to use in order to retrieve the currently active theme for use in the UI.
-   */
-  get currentThemeWithPersistedData() {
-    let data = this.currentThemeWithFallback;
-    if (data && LightweightThemePersister.persistEnabled) {
-      data = LightweightThemePersister.getPersistedData(data);
-    }
-    return data;
-  },
-
   systemThemeChanged() {
   },
 
@@ -76,10 +50,3 @@ var LightweightThemeManager = {
     }
   },
 };
-
-function _persistImages(aData, aCallback) {
-  if (AppConstants.platform != "android") {
-    // On Android, the LightweightThemeConsumer is responsible for doing this.
-    LightweightThemePersister.persistImages(aData, aCallback);
-  }
-}
diff --git a/toolkit/mozapps/extensions/internal/LightweightThemePersister.jsm b/toolkit/mozapps/extensions/internal/LightweightThemePersister.jsm
index 009b6a83c120..1023a513b32b 100644
--- a/toolkit/mozapps/extensions/internal/LightweightThemePersister.jsm
+++ b/toolkit/mozapps/extensions/internal/LightweightThemePersister.jsm
@@ -6,35 +6,24 @@
 
 var EXPORTED_SYMBOLS = ["LightweightThemePersister"];
 
-const {XPCOMUtils} = ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
+const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
 
-ChromeUtils.defineModuleGetter(this, "Services",
-  "resource://gre/modules/Services.jsm");
-
-const PERSIST_ENABLED = true;
-const PERSIST_BYPASS_CACHE = false;
-const PERSIST_FILES = {
-  headerURL: "lightweighttheme-header",
-};
+let _prefs = Services.prefs.getBranch("lightweightThemes.");
 
 ChromeUtils.defineModuleGetter(this, "LightweightThemeManager",
   "resource://gre/modules/LightweightThemeManager.jsm");
 
-XPCOMUtils.defineLazyGetter(this, "_prefs", () => {
-  return Services.prefs.getBranch("lightweightThemes.");
-});
+const PERSIST_FILES = {
+  headerURL: "lightweighttheme-header",
+};
 
 var LightweightThemePersister = {
-  get persistEnabled() {
-    return PERSIST_ENABLED;
-  },
-
   getPersistedData(aData) {
     for (let key in PERSIST_FILES) {
       try {
         if (aData[key] && _prefs.getBoolPref("persisted." + key))
           aData[key] = _getLocalImageURI(PERSIST_FILES[key]).spec
-                       + "?" + aData.id + ";" + _version(aData);
+                       + `?${aData.id};${aData.version}`;
       } catch (e) {}
     }
     return aData;
@@ -94,10 +83,7 @@ function _persistImage(sourceURL, localFileName, successCallback) {
 
   persist.persistFlags =
     Ci.nsIWebBrowserPersist.PERSIST_FLAGS_REPLACE_EXISTING_FILES |
-    Ci.nsIWebBrowserPersist.PERSIST_FLAGS_AUTODETECT_APPLY_CONVERSION |
-    (PERSIST_BYPASS_CACHE ?
-       Ci.nsIWebBrowserPersist.PERSIST_FLAGS_BYPASS_CACHE :
-       Ci.nsIWebBrowserPersist.PERSIST_FLAGS_FROM_CACHE);
+    Ci.nsIWebBrowserPersist.PERSIST_FLAGS_AUTODETECT_APPLY_CONVERSION;
 
   persist.progressListener = new _persistProgressListener(successCallback);
 
@@ -139,10 +125,6 @@ function _getLocalImageURI(localFileName) {
   return Services.io.newFileURI(localFile);
 }
 
-function _version(aThemeData) {
-  return aThemeData.version || "";
-}
-
 function _versionCode(aThemeData) {
-  return aThemeData.id + "-" + _version(aThemeData);
+  return `${aThemeData.id}-${aThemeData.version}`;
 }
diff --git a/toolkit/mozapps/extensions/internal/moz.build b/toolkit/mozapps/extensions/internal/moz.build
index 6db01bc47dfb..e6adce0800c5 100644
--- a/toolkit/mozapps/extensions/internal/moz.build
+++ b/toolkit/mozapps/extensions/internal/moz.build
@@ -11,19 +11,21 @@ EXTRA_JS_MODULES.addons += [
     'Content.js',
     'GMPProvider.jsm',
     'LightweightThemeImageOptimizer.jsm',
-    'LightweightThemePersister.jsm',
     'ProductAddonChecker.jsm',
     'XPIDatabase.jsm',
     'XPIInstall.jsm',
     'XPIProvider.jsm',
 ]
 
-TESTING_JS_MODULES += [
-    'AddonTestUtils.jsm',
-]
-
-# Don't ship unused providers on Android
-if CONFIG['MOZ_WIDGET_TOOLKIT'] != 'android':
+if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'android':
+    EXTRA_JS_MODULES.addons += [
+        'LightweightThemePersister.jsm',
+    ]
+else:
     EXTRA_JS_MODULES.addons += [
         'PluginProvider.jsm',
     ]
+
+TESTING_JS_MODULES += [
+    'AddonTestUtils.jsm',
+]