diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 1be8587236db..c49f79677c0c 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -4630,10 +4630,6 @@ pref("extensions.alwaysUnpack", false);
 pref("extensions.minCompatiblePlatformVersion", "2.0");
 pref("extensions.webExtensionsMinPlatformVersion", "42.0a1");
 
-// Other webextensions prefs
-pref("extensions.webextensions.keepStorageOnUninstall", false);
-pref("extensions.webextensions.keepUuidOnUninstall", false);
-
 pref("network.buffer.cache.count", 24);
 pref("network.buffer.cache.size",  32768);
 
diff --git a/toolkit/components/extensions/Extension.jsm b/toolkit/components/extensions/Extension.jsm
index 22b074396298..b7bf5bdf8455 100644
--- a/toolkit/components/extensions/Extension.jsm
+++ b/toolkit/components/extensions/Extension.jsm
@@ -25,9 +25,8 @@ Cu.importGlobalProperties(["TextEncoder"]);
 
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/ExtensionContent.jsm");
 
-XPCOMUtils.defineLazyModuleGetter(this, "ExtensionStorage",
-                                  "resource://gre/modules/ExtensionStorage.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "Locale",
                                   "resource://gre/modules/Locale.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "Log",
@@ -77,9 +76,6 @@ var {
 } = ExtensionUtils;
 
 const LOGGER_ID_BASE = "addons.webextension.";
-const UUID_MAP_PREF = "extensions.webextensions.uuids";
-const LEAVE_STORAGE_PREF = "extensions.webextensions.keepStorageOnUninstall";
-const LEAVE_UUID_PREF = "extensions.webextensions.keepUuidOnUninstall";
 
 const COMMENT_REGEXP = new RegExp(String.raw`
     ^
@@ -459,101 +455,29 @@ let ParentAPIManager = {
 
 ParentAPIManager.init();
 
-// All moz-extension URIs use a machine-specific UUID rather than the
-// extension's own ID in the host component. This makes it more
-// difficult for web pages to detect whether a user has a given add-on
-// installed (by trying to load a moz-extension URI referring to a
-// web_accessible_resource from the extension). UUIDMap.get()
-// returns the UUID for a given add-on ID.
-let UUIDMap = {
-  _read() {
-    let pref = Preferences.get(UUID_MAP_PREF, "{}");
-    try {
-      return JSON.parse(pref);
-    } catch (e) {
-      Cu.reportError(`Error parsing ${UUID_MAP_PREF}.`);
-      return {};
-    }
-  },
-
-  _write(map) {
-    Preferences.set(UUID_MAP_PREF, JSON.stringify(map));
-  },
-
-  get(id, create = true) {
-    let map = this._read();
-
-    if (id in map) {
-      return map[id];
-    }
-
-    let uuid = null;
-    if (create) {
-      let uuidGenerator = Cc["@mozilla.org/uuid-generator;1"].getService(Ci.nsIUUIDGenerator);
-      uuid = uuidGenerator.generateUUID().number;
-      uuid = uuid.slice(1, -1); // Strip { and } off the UUID.
-
-      map[id] = uuid;
-      this._write(map);
-    }
-    return uuid;
-  },
-
-  remove(id) {
-    let map = this._read();
-    delete map[id];
-    this._write(map);
-  },
-};
-
 // For extensions that have called setUninstallURL(), send an event
 // so the browser can display the URL.
 var UninstallObserver = {
   initialized: false,
 
-  init() {
+  init: function() {
     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
-      // (e.g., display the uninstall URL)
-      Management.emit("uninstall", extension);
+  uninit: function() {
+    if (this.initialized) {
+      AddonManager.removeAddonListener(this);
+      this.initialized = false;
     }
   },
 
-  onUninstalled(addon) {
-    let uuid = UUIDMap.get(addon.id, false);
-    if (!uuid) {
-      return;
-    }
-
-    if (!this.leaveStorage) {
-      // Clear browser.local.storage
-      ExtensionStorage.clear(addon.id);
-
-      // Clear any IndexedDB storage created by the extension
-      let baseURI = NetUtil.newURI(`moz-extension://${uuid}/`);
-      let principal = Services.scriptSecurityManager.createCodebasePrincipal(
-        baseURI, {addonId: addon.id}
-      );
-      Services.qms.clearStoragesForPrincipal(principal);
-
-      // Clear localStorage created by the extension
-      let attrs = JSON.stringify({addonId: addon.id});
-      Services.obs.notifyObservers(null, "clear-origin-data", attrs);
-    }
-
-    if (!this.leaveUuid) {
-      // Clear the entry in the UUID map
-      UUIDMap.remove(addon.id);
+  onUninstalling: function(addon) {
+    let extension = GlobalManager.extensionMap.get(addon.id);
+    if (extension) {
+      Management.emit("uninstall", extension);
     }
   },
 };
@@ -580,6 +504,7 @@ GlobalManager = {
 
     if (this.extensionMap.size == 0 && this.initialized) {
       Services.obs.removeObserver(this, "content-document-global-created");
+      UninstallObserver.uninit();
       this.initialized = false;
     }
   },
@@ -764,6 +689,36 @@ GlobalManager = {
   },
 };
 
+// All moz-extension URIs use a machine-specific UUID rather than the
+// extension's own ID in the host component. This makes it more
+// difficult for web pages to detect whether a user has a given add-on
+// installed (by trying to load a moz-extension URI referring to a
+// web_accessible_resource from the extension). getExtensionUUID
+// returns the UUID for a given add-on ID.
+function getExtensionUUID(id) {
+  const PREF_NAME = "extensions.webextensions.uuids";
+
+  let pref = Preferences.get(PREF_NAME, "{}");
+  let map = {};
+  try {
+    map = JSON.parse(pref);
+  } catch (e) {
+    Cu.reportError(`Error parsing ${PREF_NAME}.`);
+  }
+
+  if (id in map) {
+    return map[id];
+  }
+
+  let uuidGenerator = Cc["@mozilla.org/uuid-generator;1"].getService(Ci.nsIUUIDGenerator);
+  let uuid = uuidGenerator.generateUUID().number;
+  uuid = uuid.slice(1, -1); // Strip { and } off the UUID.
+
+  map[id] = uuid;
+  Preferences.set(PREF_NAME, JSON.stringify(map));
+  return uuid;
+}
+
 // Represents the data contained in an extension, contained either
 // in a directory or a zip file, which may or may not be installed.
 // This class implements the functionality of the Extension class,
@@ -818,7 +773,7 @@ ExtensionData.prototype = {
       throw new Error("getURL may not be called before an `id` or `uuid` has been set");
     }
     if (!this.uuid) {
-      this.uuid = UUIDMap.get(this.id);
+      this.uuid = getExtensionUUID(this.id);
     }
     return `moz-extension://${this.uuid}/${path}`;
   },
@@ -1094,7 +1049,7 @@ ExtensionData.prototype = {
 this.Extension = function(addonData) {
   ExtensionData.call(this, addonData.resourceURI);
 
-  this.uuid = UUIDMap.get(addonData.id);
+  this.uuid = getExtensionUUID(addonData.id);
 
   if (addonData.cleanupFile) {
     Services.obs.addObserver(this, "xpcom-shutdown", false);
@@ -1317,7 +1272,7 @@ MockExtension.prototype = {
   },
 
   shutdown() {
-    this.addon.uninstall();
+    this.addon.uninstall(true);
     return this.cleanupGeneratedFile();
   },
 
diff --git a/toolkit/components/extensions/test/mochitest/chrome.ini b/toolkit/components/extensions/test/mochitest/chrome.ini
index d312ece1e701..fd42402e5c3b 100644
--- a/toolkit/components/extensions/test/mochitest/chrome.ini
+++ b/toolkit/components/extensions/test/mochitest/chrome.ini
@@ -25,5 +25,4 @@ skip-if = buildapp == 'b2g'
 skip-if = buildapp == 'b2g'
 [test_ext_jsversion.html]
 skip-if = buildapp == 'b2g'
-[test_ext_schema.html]
-[test_chrome_ext_storage_cleanup.html]
+[test_ext_schema.html]
\ No newline at end of file
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_shutdown_cleanup.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_shutdown_cleanup.html
index 48e973f4e299..590c60af50bb 100644
--- a/toolkit/components/extensions/test/mochitest/test_chrome_ext_shutdown_cleanup.html
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_shutdown_cleanup.html
@@ -18,13 +18,18 @@ const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://testing-common/TestUtils.jsm");
 
-const {GlobalManager} = Cu.import("resource://gre/modules/Extension.jsm");
+const {
+ GlobalManager,
+ UninstallObserver,
+} = Cu.import("resource://gre/modules/Extension.jsm");
 
 /* eslint-disable mozilla/balanced-listeners */
 
 add_task(function* testShutdownCleanup() {
   is(GlobalManager.initialized, false,
      "GlobalManager start as not initialized");
+  is(UninstallObserver.initialized, false,
+     "UninstallObserver start as not initialized");
 
   let extension = ExtensionTestUtils.loadExtension({
     background: "new " + function() {
@@ -38,11 +43,15 @@ add_task(function* testShutdownCleanup() {
 
   is(GlobalManager.initialized, true,
      "GlobalManager has been initialized once an extension is started");
+  is(UninstallObserver.initialized, true,
+     "UninstallObserver has been initialized once an extension is started");
 
   yield extension.unload();
 
   is(GlobalManager.initialized, false,
      "GlobalManager has been uninitialized once all the webextensions have been stopped");
+  is(UninstallObserver.initialized, false,
+     "UninstallObserver has been uninitialized once all the webextensions have been stopped");
 });
 </script>
 
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_storage_cleanup.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_storage_cleanup.html
deleted file mode 100644
index f3f825e426b3..000000000000
--- a/toolkit/components/extensions/test/mochitest/test_chrome_ext_storage_cleanup.html
+++ /dev/null
@@ -1,161 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<head>
-  <title>WebExtension test</title>
-  <script type="text/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
-  <script type="text/javascript" src="chrome://mochikit/content/tests/SimpleTest/SpawnTask.js"></script>
-  <script type="text/javascript" src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
-  <script type="text/javascript" src="head.js"></script>
-  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
-</head>
-<body>
-
-<script type="text/javascript">
-"use strict";
-
-// Test that storage used by a webextension (through localStorage,
-// indexedDB, and browser.storage.local) gets cleaned up when the
-// extension is uninstalled.
-add_task(function* test_uninstall() {
-  function writeData() {
-    localStorage.setItem("hello", "world");
-
-    let idbPromise = new Promise((resolve, reject) => {
-      let req = indexedDB.open("test");
-      req.onerror = e => {
-        reject(new Error(`indexedDB open failed with ${e.errorCode}`));
-      };
-
-      req.onupgradeneeded = e => {
-        let db = e.target.result;
-        db.createObjectStore("store", {keyPath: "name"});
-      };
-
-      req.onsuccess = e => {
-        let db = e.target.result;
-        let transaction = db.transaction("store", "readwrite");
-        let addreq = transaction.objectStore("store")
-                                .add({name: "hello", value: "world"});
-        addreq.onerror = e => {
-          reject(new Error(`add to indexedDB failed with ${e.errorCode}`));
-        };
-        addreq.onsuccess = e => {
-          resolve();
-        };
-      };
-    });
-
-    let browserStoragePromise = browser.storage.local.set({hello: "world"});
-
-    Promise.all([idbPromise, browserStoragePromise]).then(() => {
-      browser.test.sendMessage("finished");
-    });
-  }
-
-  function readData() {
-    let matchLocalStorage = (localStorage.getItem("hello") == "world");
-
-    let idbPromise = new Promise((resolve, reject) => {
-      let req = indexedDB.open("test");
-      req.onerror = e => {
-        reject(new Error(`indexedDB open failed with ${e.errorCode}`));
-      };
-
-      req.onupgradeneeded = e => {
-        // no database, data is not present
-        resolve(false);
-      };
-
-      req.onsuccess = e => {
-        let db = e.target.result;
-        let transaction = db.transaction("store", "readwrite");
-        let addreq = transaction.objectStore("store").get("hello");
-        addreq.onerror = e => {
-          reject(new Error(`read from indexedDB failed with ${e.errorCode}`));
-        };
-        addreq.onsuccess = e => {
-          let match = (addreq.result.value == "world");
-          resolve(match);
-        };
-      };
-    });
-
-    let browserStoragePromise = browser.storage.local.get("hello").then(result => {
-      return (Object.keys(result).length == 1 && result.hello == "world");
-    });
-
-    Promise.all([idbPromise, browserStoragePromise])
-           .then(([matchIDB, matchBrowserStorage]) => {
-             let result = {matchLocalStorage, matchIDB, matchBrowserStorage};
-             browser.test.sendMessage("results", result);
-           });
-  }
-
-  const ID = "storage.cleanup@tests.mozilla.org";
-
-  // Use a test-only pref to leave the addonid->uuid mapping around after
-  // uninstall so that we can re-attach to the same storage.  Also set
-  // the pref to prevent cleaning up storage on uninstall so we can test
-  // that the "keep uuid" logic works correctly.  Do the storage flag in
-  // a separate prefEnv so we can pop it below, leaving the uuid flag set.
-  yield SpecialPowers.pushPrefEnv({
-    set: [["extensions.webextensions.keepUuidOnUninstall", true]],
-  });
-  yield SpecialPowers.pushPrefEnv({
-    set: [["extensions.webextensions.keepStorageOnUninstall", true]],
-  });
-
-  let extension = ExtensionTestUtils.loadExtension({
-    background: `(${writeData})()`,
-    manifest: {
-      permissions: ["storage"],
-    },
-    useAddonManager: true,
-  }, ID);
-
-  yield extension.startup();
-  yield extension.awaitMessage("finished");
-  yield extension.unload();
-
-  // Check that we can still see data we wrote to storage but clear the
-  // "leave storage" flag so our storaged gets cleared on uninstall.
-  // This effectively tests the keepUuidOnUninstall logic, which ensures
-  // that when we read storage again and check that it is cleared, that
-  // it is actually a meaningful test!
-  yield SpecialPowers.popPrefEnv();
-  extension = ExtensionTestUtils.loadExtension({
-    background: `(${readData})()`,
-    manifest: {
-      permissions: ["storage"],
-    },
-    useAddonManager: true,
-  }, ID);
-
-  yield extension.startup();
-  let results = yield extension.awaitMessage("results");
-  is(results.matchLocalStorage, true, "localStorage data is still present");
-  is(results.matchIDB, true, "indexedDB data is still present");
-  is(results.matchBrowserStorage, true, "browser.storage.local data is still present");
-
-  yield extension.unload();
-
-  // Read again.  This time, our data should be gone.
-  extension = ExtensionTestUtils.loadExtension({
-    background: `(${readData})()`,
-    manifest: {
-      permissions: ["storage"],
-    },
-    useAddonManager: true,
-  }, ID);
-
-  yield extension.startup();
-  results = yield extension.awaitMessage("results");
-  is(results.matchLocalStorage, false, "localStorage data was cleared");
-  is(results.matchIDB, false, "indexedDB data was cleared");
-  is(results.matchBrowserStorage, false, "browser.storage.local data was cleared");
-  yield extension.unload();
-});
-</script>
-
-</body>
-</html>