diff --git a/browser/components/extensions/test/xpcshell/.eslintrc b/browser/components/extensions/test/xpcshell/.eslintrc
index 03381914eed7..60fdab2176e8 100644
--- a/browser/components/extensions/test/xpcshell/.eslintrc
+++ b/browser/components/extensions/test/xpcshell/.eslintrc
@@ -1,7 +1,3 @@
 {
   "extends": "../../../../../testing/xpcshell/xpcshell.eslintrc",
-
-  "globals": {
-    "browser": false,
-  },
 }
diff --git a/browser/components/extensions/test/xpcshell/head.js b/browser/components/extensions/test/xpcshell/head.js
index de4a4a3f6e98..032d01012e7e 100644
--- a/browser/components/extensions/test/xpcshell/head.js
+++ b/browser/components/extensions/test/xpcshell/head.js
@@ -2,24 +2,12 @@
 
 const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
 
-/* exported createHttpServer */
-
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
 
-XPCOMUtils.defineLazyModuleGetter(this, "AppConstants",
-                                  "resource://gre/modules/AppConstants.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "Extension",
                                   "resource://gre/modules/Extension.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "ExtensionData",
                                   "resource://gre/modules/Extension.jsm");
-XPCOMUtils.defineLazyModuleGetter(this, "ExtensionManagement",
-                                  "resource://gre/modules/ExtensionManagement.jsm");
-XPCOMUtils.defineLazyModuleGetter(this, "ExtensionTestUtils",
-                                  "resource://testing-common/ExtensionXPCShellUtils.jsm");
-XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
-                                  "resource://gre/modules/FileUtils.jsm");
-XPCOMUtils.defineLazyModuleGetter(this, "HttpServer",
-                                  "resource://testing-common/httpd.js");
 XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
                                   "resource://gre/modules/NetUtil.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "Schemas",
@@ -27,29 +15,36 @@ XPCOMUtils.defineLazyModuleGetter(this, "Schemas",
 XPCOMUtils.defineLazyModuleGetter(this, "Services",
                                   "resource://gre/modules/Services.jsm");
 
-ExtensionTestUtils.init(this);
+/* exported normalizeManifest */
 
+let BASE_MANIFEST = {
+  "applications": {"gecko": {"id": "test@web.ext"}},
 
-/**
- * Creates a new HttpServer for testing, and begins listening on the
- * specified port. Automatically shuts down the server when the test
- * unit ends.
- *
- * @param {integer} [port]
- *        The port to listen on. If omitted, listen on a random
- *        port. The latter is the preferred behavior.
- *
- * @returns {HttpServer}
- */
-function createHttpServer(port = -1) {
-  let server = new HttpServer();
-  server.start(port);
+  "manifest_version": 2,
 
-  do_register_cleanup(() => {
-    return new Promise(resolve => {
-      server.stop(resolve);
-    });
-  });
+  "name": "name",
+  "version": "0",
+};
 
-  return server;
+function* normalizeManifest(manifest, baseManifest = BASE_MANIFEST) {
+  const {Management} = Cu.import("resource://gre/modules/Extension.jsm", {});
+  yield Management.lazyInit();
+
+  let errors = [];
+  let context = {
+    url: null,
+
+    logError: error => {
+      errors.push(error);
+    },
+
+    preprocessors: {},
+  };
+
+  manifest = Object.assign({}, baseManifest, manifest);
+
+  let normalized = Schemas.normalize(manifest, "manifest.WebExtensionManifest", context);
+  normalized.errors = errors;
+
+  return normalized;
 }
diff --git a/browser/components/extensions/test/xpcshell/test_ext_manifest_commands.js b/browser/components/extensions/test/xpcshell/test_ext_manifest_commands.js
index 4de7afe01ab6..237ea953cb94 100644
--- a/browser/components/extensions/test/xpcshell/test_ext_manifest_commands.js
+++ b/browser/components/extensions/test/xpcshell/test_ext_manifest_commands.js
@@ -4,7 +4,7 @@
 
 
 add_task(function* test_manifest_commands() {
-  let normalized = yield ExtensionTestUtils.normalizeManifest({
+  let normalized = yield normalizeManifest({
     "commands": {
       "toggle-feature": {
         "suggested_key": {"default": "Shifty+Y"},
diff --git a/toolkit/components/extensions/Extension.jsm b/toolkit/components/extensions/Extension.jsm
index 3f853e695fef..b5ba41f565ff 100644
--- a/toolkit/components/extensions/Extension.jsm
+++ b/toolkit/components/extensions/Extension.jsm
@@ -56,7 +56,6 @@ XPCOMUtils.defineLazyModuleGetter(this, "MessageChannel",
 XPCOMUtils.defineLazyModuleGetter(this, "AddonManager",
                                   "resource://gre/modules/AddonManager.jsm");
 
-Cu.import("resource://gre/modules/ExtensionContent.jsm");
 Cu.import("resource://gre/modules/ExtensionManagement.jsm");
 
 const BASE_SCHEMA = "chrome://extensions/content/schemas/manifest.json";
@@ -327,7 +326,7 @@ class ProxyContext extends ExtensionContext {
 
 function findPathInObject(obj, path) {
   for (let elt of path) {
-    obj = obj[elt] || undefined;
+    obj = obj[elt];
   }
   return obj;
 }
diff --git a/toolkit/components/extensions/ExtensionXPCShellUtils.jsm b/toolkit/components/extensions/ExtensionXPCShellUtils.jsm
deleted file mode 100644
index 10a7b47f6064..000000000000
--- a/toolkit/components/extensions/ExtensionXPCShellUtils.jsm
+++ /dev/null
@@ -1,285 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-"use strict";
-
-this.EXPORTED_SYMBOLS = ["ExtensionTestUtils"];
-
-const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
-
-Components.utils.import("resource://gre/modules/Task.jsm");
-Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
-
-XPCOMUtils.defineLazyModuleGetter(this, "Extension",
-                                  "resource://gre/modules/Extension.jsm");
-XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
-                                  "resource://gre/modules/FileUtils.jsm");
-XPCOMUtils.defineLazyModuleGetter(this, "Schemas",
-                                  "resource://gre/modules/Schemas.jsm");
-XPCOMUtils.defineLazyModuleGetter(this, "Services",
-                                  "resource://gre/modules/Services.jsm");
-
-XPCOMUtils.defineLazyServiceGetter(this, "uuidGenerator",
-                                   "@mozilla.org/uuid-generator;1", "nsIUUIDGenerator");
-
-/* exported ExtensionTestUtils */
-
-let BASE_MANIFEST = Object.freeze({
-  "applications": Object.freeze({
-    "gecko": Object.freeze({
-      "id": "test@web.ext",
-    }),
-  }),
-
-  "manifest_version": 2,
-
-  "name": "name",
-  "version": "0",
-});
-
-class ExtensionWrapper {
-  constructor(extension, testScope) {
-    this.extension = extension;
-    this.testScope = testScope;
-
-    this.state = "uninitialized";
-
-    this.testResolve = null;
-    this.testDone = new Promise(resolve => { this.testResolve = resolve; });
-
-    this.messageHandler = new Map();
-    this.messageAwaiter = new Map();
-
-    this.messageQueue = new Set();
-
-    this.testScope.do_register_cleanup(() => {
-      if (this.messageQueue.size) {
-        let names = Array.from(this.messageQueue, ([msg]) => msg);
-        this.testScope.equal(JSON.stringify(names), "[]", "message queue is empty");
-      }
-      if (this.messageAwaiter.size) {
-        let names = Array.from(this.messageAwaiter.keys());
-        this.testScope.equal(JSON.stringify(names), "[]", "no tasks awaiting on messages");
-      }
-    });
-
-    /* eslint-disable mozilla/balanced-listeners */
-    extension.on("test-eq", (kind, pass, msg, expected, actual) => {
-      this.testScope.ok(pass, `${msg} - Expected: ${expected}, Actual: ${actual}`);
-    });
-    extension.on("test-log", (kind, pass, msg) => {
-      this.testScope.do_print(msg);
-    });
-    extension.on("test-result", (kind, pass, msg) => {
-      this.testScope.ok(pass, msg);
-    });
-    extension.on("test-done", (kind, pass, msg, expected, actual) => {
-      this.testScope.ok(pass, msg);
-      this.testResolve(msg);
-    });
-
-    extension.on("test-message", (kind, msg, ...args) => {
-      let handler = this.messageHandler.get(msg);
-      if (handler) {
-        handler(...args);
-      } else {
-        this.messageQueue.add([msg, ...args]);
-        this.checkMessages();
-      }
-    });
-    /* eslint-enable mozilla/balanced-listeners */
-
-    this.testScope.do_register_cleanup(() => {
-      if (this.state == "pending" || this.state == "running") {
-        this.testScope.equal(this.state, "unloaded", "Extension left running at test shutdown");
-        return this.unload();
-      } else if (extension.state == "unloading") {
-        this.testScope.equal(this.state, "unloaded", "Extension not fully unloaded at test shutdown");
-      }
-    });
-
-    this.testScope.do_print(`Extension loaded`);
-  }
-
-  startup() {
-    if (this.state != "uninitialized") {
-      throw new Error("Extension already started");
-    }
-    this.state = "pending";
-
-    return this.extension.startup().then(
-      result => {
-        this.state = "running";
-
-        return result;
-      },
-      error => {
-        this.state = "failed";
-
-        return Promise.reject(error);
-      });
-  }
-
-  unload() {
-    if (this.state != "running") {
-      throw new Error("Extension not running");
-    }
-    this.state = "unloading";
-
-    this.extension.shutdown();
-    this.state = "unloaded";
-
-    return Promise.resolve();
-  }
-
-  sendMessage(...args) {
-    this.extension.testMessage(...args);
-  }
-
-  awaitFinish(msg) {
-    return this.testDone.then(actual => {
-      if (msg) {
-        this.testScope.equal(actual, msg, "test result correct");
-      }
-      return actual;
-    });
-  }
-
-  checkMessages() {
-    for (let message of this.messageQueue) {
-      let [msg, ...args] = message;
-
-      let listener = this.messageAwaiter.get(msg);
-      if (listener) {
-        this.messageQueue.delete(message);
-        this.messageAwaiter.delete(msg);
-
-        listener.resolve(...args);
-        return;
-      }
-    }
-  }
-
-  checkDuplicateListeners(msg) {
-    if (this.messageHandler.has(msg) || this.messageAwaiter.has(msg)) {
-      throw new Error("only one message handler allowed");
-    }
-  }
-
-  awaitMessage(msg) {
-    return new Promise(resolve => {
-      this.checkDuplicateListeners(msg);
-
-      this.messageAwaiter.set(msg, {resolve});
-      this.checkMessages();
-    });
-  }
-
-  onMessage(msg, callback) {
-    this.checkDuplicateListeners(msg);
-    this.messageHandler.set(msg, callback);
-  }
-}
-
-var ExtensionTestUtils = {
-  BASE_MANIFEST,
-
-  normalizeManifest: Task.async(function* (manifest, baseManifest = BASE_MANIFEST) {
-    const {Management} = Cu.import("resource://gre/modules/Extension.jsm", {});
-
-    yield Management.lazyInit();
-
-    let errors = [];
-    let context = {
-      url: null,
-
-      logError: error => {
-        errors.push(error);
-      },
-
-      preprocessors: {},
-    };
-
-    manifest = Object.assign({}, baseManifest, manifest);
-
-    let normalized = Schemas.normalize(manifest, "manifest.WebExtensionManifest", context);
-    normalized.errors = errors;
-
-    return normalized;
-  }),
-
-  currentScope: null,
-
-  profileDir: null,
-
-  init(scope) {
-    this.currentScope = scope;
-
-    this.profileDir = scope.do_get_profile();
-
-    // We need to load at least one frame script into every message
-    // manager to ensure that the scriptable wrapper for its global gets
-    // created before we try to access it externally. If we don't, we
-    // fail sanity checks on debug builds the first time we try to
-    // create a wrapper, because we should never have a global without a
-    // cached wrapper.
-    Services.mm.loadFrameScript("data:text/javascript,//", true);
-
-
-    let tmpD = this.profileDir.clone();
-    tmpD.append("tmp");
-    tmpD.create(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
-
-    let dirProvider = {
-      getFile(prop, persistent) {
-        persistent.value = false;
-        if (prop == "TmpD") {
-          return tmpD.clone();
-        }
-        return null;
-      },
-
-      QueryInterface: XPCOMUtils.generateQI([Ci.nsIDirectoryServiceProvider]),
-    };
-    Services.dirsvc.registerProvider(dirProvider);
-
-
-    scope.do_register_cleanup(() => {
-      tmpD.remove(true);
-      Services.dirsvc.unregisterProvider(dirProvider);
-
-      this.currentScope = null;
-    });
-  },
-
-  addonManagerStarted: false,
-
-  startAddonManager() {
-    if (this.addonManagerStarted) {
-      return;
-    }
-    this.addonManagerStarted = true;
-
-    let appInfo = {};
-    Cu.import("resource://testing-common/AppInfo.jsm", appInfo);
-
-    appInfo.updateAppInfo({
-      ID: "xpcshell@tests.mozilla.org",
-      name: "XPCShell",
-      version: "48",
-      platformVersion: "48",
-    });
-
-
-    let manager = Cc["@mozilla.org/addons/integration;1"].getService(Ci.nsIObserver)
-                                                         .QueryInterface(Ci.nsITimerCallback);
-    manager.observe(null, "addons-startup", null);
-  },
-
-  loadExtension(data, id = uuidGenerator.generateUUID().number) {
-    let extension = Extension.generate(id, data);
-
-    return new ExtensionWrapper(extension, this.currentScope);
-  },
-};
diff --git a/toolkit/components/extensions/moz.build b/toolkit/components/extensions/moz.build
index a810f3e7c298..f8bac0b63b70 100644
--- a/toolkit/components/extensions/moz.build
+++ b/toolkit/components/extensions/moz.build
@@ -19,10 +19,6 @@ EXTRA_COMPONENTS += [
     'extensions-toolkit.manifest',
 ]
 
-TESTING_JS_MODULES += [
-    'ExtensionXPCShellUtils.jsm',
-]
-
 DIRS += ['schemas']
 
 JAR_MANIFESTS += ['jar.mn']
diff --git a/toolkit/components/extensions/test/xpcshell/.eslintrc b/toolkit/components/extensions/test/xpcshell/.eslintrc
index 03381914eed7..60fdab2176e8 100644
--- a/toolkit/components/extensions/test/xpcshell/.eslintrc
+++ b/toolkit/components/extensions/test/xpcshell/.eslintrc
@@ -1,7 +1,3 @@
 {
   "extends": "../../../../../testing/xpcshell/xpcshell.eslintrc",
-
-  "globals": {
-    "browser": false,
-  },
 }
diff --git a/toolkit/components/extensions/test/xpcshell/head.js b/toolkit/components/extensions/test/xpcshell/head.js
index f427a1cec116..0a7d4e22603c 100644
--- a/toolkit/components/extensions/test/xpcshell/head.js
+++ b/toolkit/components/extensions/test/xpcshell/head.js
@@ -8,8 +8,6 @@ XPCOMUtils.defineLazyModuleGetter(this, "Extension",
                                   "resource://gre/modules/Extension.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "ExtensionData",
                                   "resource://gre/modules/Extension.jsm");
-XPCOMUtils.defineLazyModuleGetter(this, "ExtensionTestUtils",
-                                  "resource://testing-common/ExtensionXPCShellUtils.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
                                   "resource://gre/modules/NetUtil.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "Schemas",
@@ -17,4 +15,37 @@ XPCOMUtils.defineLazyModuleGetter(this, "Schemas",
 XPCOMUtils.defineLazyModuleGetter(this, "Services",
                                   "resource://gre/modules/Services.jsm");
 
-ExtensionTestUtils.init(this);
+/* exported normalizeManifest */
+
+let BASE_MANIFEST = {
+  "applications": {"gecko": {"id": "test@web.ext"}},
+
+  "manifest_version": 2,
+
+  "name": "name",
+  "version": "0",
+};
+
+function* normalizeManifest(manifest, baseManifest = BASE_MANIFEST) {
+  const {Management} = Cu.import("resource://gre/modules/Extension.jsm", {});
+
+  yield Management.lazyInit();
+
+  let errors = [];
+  let context = {
+    url: null,
+
+    logError: error => {
+      errors.push(error);
+    },
+
+    preprocessors: {},
+  };
+
+  manifest = Object.assign({}, baseManifest, manifest);
+
+  let normalized = Schemas.normalize(manifest, "manifest.WebExtensionManifest", context);
+  normalized.errors = errors;
+
+  return normalized;
+}
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_manifest_content_security_policy.js b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_content_security_policy.js
index 2b0084980c7a..f65c4e33f4d1 100644
--- a/toolkit/components/extensions/test/xpcshell/test_ext_manifest_content_security_policy.js
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_content_security_policy.js
@@ -4,7 +4,7 @@
 
 
 add_task(function* test_manifest_csp() {
-  let normalized = yield ExtensionTestUtils.normalizeManifest({
+  let normalized = yield normalizeManifest({
     "content_security_policy": "script-src 'self'; object-src 'none'",
   });
 
@@ -15,7 +15,7 @@ add_task(function* test_manifest_csp() {
         "Should have the expected poilcy string");
 
 
-  normalized = yield ExtensionTestUtils.normalizeManifest({
+  normalized = yield normalizeManifest({
     "content_security_policy": "object-src 'none'",
   });
 
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_manifest_incognito.js b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_incognito.js
index 94649692e90c..2f48179d919c 100644
--- a/toolkit/components/extensions/test/xpcshell/test_ext_manifest_incognito.js
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_incognito.js
@@ -4,7 +4,7 @@
 
 
 add_task(function* test_manifest_incognito() {
-  let normalized = yield ExtensionTestUtils.normalizeManifest({
+  let normalized = yield normalizeManifest({
     "incognito": "spanning",
   });
 
@@ -14,7 +14,7 @@ add_task(function* test_manifest_incognito() {
         "spanning",
         "Should have the expected incognito string");
 
-  normalized = yield ExtensionTestUtils.normalizeManifest({
+  normalized = yield normalizeManifest({
     "incognito": "split",
   });