diff --git a/browser/components/extensions/ExtensionControlledPopup.jsm b/browser/components/extensions/ExtensionControlledPopup.jsm
index c1e1fa8447e1..d74f90194cae 100644
--- a/browser/components/extensions/ExtensionControlledPopup.jsm
+++ b/browser/components/extensions/ExtensionControlledPopup.jsm
@@ -21,6 +21,7 @@ var EXPORTED_SYMBOLS = ["ExtensionControlledPopup"];
 
 ChromeUtils.import("resource://gre/modules/Services.jsm");
 ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
+ChromeUtils.import("resource://gre/modules/ExtensionCommon.jsm");
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
 
 ChromeUtils.defineModuleGetter(this, "AddonManager",
@@ -32,7 +33,9 @@ ChromeUtils.defineModuleGetter(this, "CustomizableUI",
 ChromeUtils.defineModuleGetter(this, "ExtensionSettingsStore",
                                "resource://gre/modules/ExtensionSettingsStore.jsm");
 
-let {makeWidgetId} = ExtensionUtils;
+let {
+  makeWidgetId,
+} = ExtensionCommon;
 
 XPCOMUtils.defineLazyGetter(this, "strBundle", function() {
   return Services.strings.createBundle("chrome://global/locale/extensions.properties");
diff --git a/browser/components/extensions/ExtensionPopups.jsm b/browser/components/extensions/ExtensionPopups.jsm
index 2370c60db6a4..fdce3ab26079 100644
--- a/browser/components/extensions/ExtensionPopups.jsm
+++ b/browser/components/extensions/ExtensionPopups.jsm
@@ -18,14 +18,18 @@ ChromeUtils.defineModuleGetter(this, "setTimeout",
                                "resource://gre/modules/Timer.jsm");
 
 ChromeUtils.import("resource://gre/modules/AppConstants.jsm");
+ChromeUtils.import("resource://gre/modules/ExtensionCommon.jsm");
 ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
 
 var {
   DefaultWeakMap,
-  makeWidgetId,
   promiseEvent,
 } = ExtensionUtils;
 
+const {
+  makeWidgetId,
+} = ExtensionCommon;
+
 
 const POPUP_LOAD_TIMEOUT_MS = 200;
 
diff --git a/browser/components/extensions/child/ext-devtools-panels.js b/browser/components/extensions/child/ext-devtools-panels.js
index 82a2ab8dbefc..d9150fd6616b 100644
--- a/browser/components/extensions/child/ext-devtools-panels.js
+++ b/browser/components/extensions/child/ext-devtools-panels.js
@@ -18,7 +18,7 @@ var {
  * @param {string} panelOptions.id
  *   The id of the addon devtools panel registered in the main process.
  */
-class ChildDevToolsPanel extends ExtensionUtils.EventEmitter {
+class ChildDevToolsPanel extends ExtensionCommon.EventEmitter {
   constructor(context, {id}) {
     super();
 
@@ -144,7 +144,7 @@ class ChildDevToolsPanel extends ExtensionUtils.EventEmitter {
  * @param {string} sidebarOptions.id
  *   The id of the addon devtools sidebar registered in the main process.
  */
-class ChildDevToolsInspectorSidebar extends ExtensionUtils.EventEmitter {
+class ChildDevToolsInspectorSidebar extends ExtensionCommon.EventEmitter {
   constructor(context, {id}) {
     super();
 
diff --git a/browser/components/extensions/child/ext-menus.js b/browser/components/extensions/child/ext-menus.js
index b1dd7a366352..f252350a7188 100644
--- a/browser/components/extensions/child/ext-menus.js
+++ b/browser/components/extensions/child/ext-menus.js
@@ -4,7 +4,7 @@
 
 var {
   withHandlingUserInput,
-} = ExtensionUtils;
+} = ExtensionCommon;
 
 // If id is not specified for an item we use an integer.
 // This ID need only be unique within a single addon. Since all addon code that
diff --git a/browser/components/extensions/parent/ext-browser.js b/browser/components/extensions/parent/ext-browser.js
index f7711a5599b0..55ca09c6e54e 100644
--- a/browser/components/extensions/parent/ext-browser.js
+++ b/browser/components/extensions/parent/ext-browser.js
@@ -13,9 +13,12 @@ ChromeUtils.defineModuleGetter(this, "BrowserWindowTracker",
 
 var {
   ExtensionError,
-  defineLazyGetter,
 } = ExtensionUtils;
 
+var {
+  defineLazyGetter,
+} = ExtensionCommon;
+
 const READER_MODE_PREFIX = "about:reader";
 
 let tabTracker;
@@ -31,8 +34,8 @@ const getSender = (extension, target, sender) => {
     // page-open listener below).
     tabId = sender.tabId;
     delete sender.tabId;
-  } else if (ExtensionUtils.instanceOf(target, "XULElement") ||
-             ExtensionUtils.instanceOf(target, "HTMLIFrameElement")) {
+  } else if (ExtensionCommon.instanceOf(target, "XULElement") ||
+             ExtensionCommon.instanceOf(target, "HTMLIFrameElement")) {
     tabId = tabTracker.getBrowserData(target).tabId;
   }
 
diff --git a/browser/components/extensions/parent/ext-history.js b/browser/components/extensions/parent/ext-history.js
index b5a995b2a908..997e92d27064 100644
--- a/browser/components/extensions/parent/ext-history.js
+++ b/browser/components/extensions/parent/ext-history.js
@@ -9,7 +9,7 @@ ChromeUtils.defineModuleGetter(this, "Services",
 
 var {
   normalizeTime,
-} = ExtensionUtils;
+} = ExtensionCommon;
 
 let nsINavHistoryService = Ci.nsINavHistoryService;
 const TRANSITION_TO_TRANSITION_TYPES_MAP = new Map([
diff --git a/browser/components/extensions/test/xpcshell/test_ext_history.js b/browser/components/extensions/test/xpcshell/test_ext_history.js
index e8d38f2baba9..4048a692bcfd 100644
--- a/browser/components/extensions/test/xpcshell/test_ext_history.js
+++ b/browser/components/extensions/test/xpcshell/test_ext_history.js
@@ -6,8 +6,8 @@ ChromeUtils.defineModuleGetter(this, "PlacesTestUtils",
                                "resource://testing-common/PlacesTestUtils.jsm");
 ChromeUtils.defineModuleGetter(this, "PlacesUtils",
                                "resource://gre/modules/PlacesUtils.jsm");
-ChromeUtils.defineModuleGetter(this, "ExtensionUtils",
-                               "resource://gre/modules/ExtensionUtils.jsm");
+ChromeUtils.defineModuleGetter(this, "ExtensionCommon",
+                               "resource://gre/modules/ExtensionCommon.jsm");
 
 ChromeUtils.import("resource://testing-common/PromiseTestUtils.jsm");
 
@@ -308,7 +308,7 @@ add_task(async function test_add_url() {
     equal(results.result.title, results.details.title, "URL was added with the correct title");
     if (results.details.visitTime) {
       equal(results.result.lastVisitTime,
-            Number(ExtensionUtils.normalizeTime(results.details.visitTime)),
+            Number(ExtensionCommon.normalizeTime(results.details.visitTime)),
             "URL was added with the correct date");
     }
   }
diff --git a/mobile/android/components/extensions/ext-utils.js b/mobile/android/components/extensions/ext-utils.js
index 60497dd91d5c..4b4f218d44c2 100644
--- a/mobile/android/components/extensions/ext-utils.js
+++ b/mobile/android/components/extensions/ext-utils.js
@@ -9,14 +9,18 @@ ChromeUtils.defineModuleGetter(this, "PrivateBrowsingUtils",
 /* globals EventDispatcher */
 ChromeUtils.import("resource://gre/modules/Messaging.jsm");
 
+ChromeUtils.import("resource://gre/modules/ExtensionCommon.jsm");
 ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
 
 var {
   DefaultWeakMap,
   ExtensionError,
-  defineLazyGetter,
 } = ExtensionUtils;
 
+var {
+  defineLazyGetter,
+} = ExtensionCommon;
+
 global.GlobalEventDispatcher = EventDispatcher.instance;
 
 const BrowserStatusFilter = Components.Constructor(
diff --git a/toolkit/components/extensions/Extension.jsm b/toolkit/components/extensions/Extension.jsm
index f523ecce4ac8..ac147703ac8e 100644
--- a/toolkit/components/extensions/Extension.jsm
+++ b/toolkit/components/extensions/Extension.jsm
@@ -42,7 +42,6 @@ XPCOMUtils.defineLazyModuleGetters(this, {
   AppConstants: "resource://gre/modules/AppConstants.jsm",
   AsyncShutdown: "resource://gre/modules/AsyncShutdown.jsm",
   ContextualIdentityService: "resource://gre/modules/ContextualIdentityService.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",
@@ -77,6 +76,7 @@ XPCOMUtils.defineLazyGetter(
   () => Services.io.getProtocolHandler("resource")
           .QueryInterface(Ci.nsIResProtocolHandler));
 
+ChromeUtils.import("resource://gre/modules/ExtensionCommon.jsm");
 ChromeUtils.import("resource://gre/modules/ExtensionParent.jsm");
 ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
 
@@ -96,12 +96,15 @@ var {
 } = ExtensionParent;
 
 const {
-  EventEmitter,
   getUniqueId,
   promiseTimeout,
 } = ExtensionUtils;
 
-XPCOMUtils.defineLazyGetter(this, "console", ExtensionUtils.getConsole);
+const {
+  EventEmitter,
+} = ExtensionCommon;
+
+XPCOMUtils.defineLazyGetter(this, "console", ExtensionCommon.getConsole);
 
 XPCOMUtils.defineLazyGetter(this, "LocaleData", () => ExtensionCommon.LocaleData);
 
@@ -1430,7 +1433,7 @@ class Extension extends ExtensionData {
       return true;
     }
 
-    return ExtensionUtils.checkLoadURL(url, this.principal, options);
+    return ExtensionCommon.checkLoadURL(url, this.principal, options);
   }
 
   async promiseLocales(locale) {
diff --git a/toolkit/components/extensions/ExtensionChild.jsm b/toolkit/components/extensions/ExtensionChild.jsm
index a921331edc55..33de509f96f7 100644
--- a/toolkit/components/extensions/ExtensionChild.jsm
+++ b/toolkit/components/extensions/ExtensionChild.jsm
@@ -42,21 +42,21 @@ ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
 
 const {
   DefaultMap,
-  EventEmitter,
   LimitedSet,
-  defineLazyGetter,
   getMessageManager,
   getUniqueId,
   getWinUtils,
-  withHandlingUserInput,
 } = ExtensionUtils;
 
 const {
+  EventEmitter,
   EventManager,
   LocalAPIImplementation,
   LocaleData,
   NoCloneSpreadArgs,
   SchemaAPIInterface,
+  defineLazyGetter,
+  withHandlingUserInput,
 } = ExtensionCommon;
 
 const isContentProcess = Services.appinfo.processType == Services.appinfo.PROCESS_TYPE_CONTENT;
diff --git a/toolkit/components/extensions/ExtensionCommon.jsm b/toolkit/components/extensions/ExtensionCommon.jsm
index fded102c4a95..489d58c0c435 100644
--- a/toolkit/components/extensions/ExtensionCommon.jsm
+++ b/toolkit/components/extensions/ExtensionCommon.jsm
@@ -22,6 +22,7 @@ XPCOMUtils.defineLazyGlobalGetters(this, ["fetch"]);
 
 XPCOMUtils.defineLazyModuleGetters(this, {
   AppConstants: "resource://gre/modules/AppConstants.jsm",
+  ConsoleAPI: "resource://gre/modules/Console.jsm",
   MessageChannel: "resource://gre/modules/MessageChannel.jsm",
   PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.jsm",
   Schemas: "resource://gre/modules/Schemas.jsm",
@@ -37,16 +38,20 @@ ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
 var {
   DefaultMap,
   DefaultWeakMap,
-  EventEmitter,
   ExtensionError,
-  defineLazyGetter,
   filterStack,
-  getConsole,
   getInnerWindowID,
   getUniqueId,
   getWinUtils,
 } = ExtensionUtils;
 
+function getConsole() {
+  return new ConsoleAPI({
+    maxLogLevelPref: "extensions.webextensions.log.level",
+    prefix: "WebExtensions",
+  });
+}
+
 XPCOMUtils.defineLazyGetter(this, "console", getConsole);
 
 XPCOMUtils.defineLazyPreferenceGetter(this, "DELAYED_BG_STARTUP",
@@ -54,6 +59,121 @@ XPCOMUtils.defineLazyPreferenceGetter(this, "DELAYED_BG_STARTUP",
 
 var ExtensionCommon;
 
+// Run a function and report exceptions.
+function runSafeSyncWithoutClone(f, ...args) {
+  try {
+    return f(...args);
+  } catch (e) {
+    dump(`Extension error: ${e} ${e.fileName} ${e.lineNumber}\n[[Exception stack\n${filterStack(e)}Current stack\n${filterStack(Error())}]]\n`);
+    Cu.reportError(e);
+  }
+}
+
+// Return true if the given value is an instance of the given
+// native type.
+function instanceOf(value, type) {
+  return (value && typeof value === "object" &&
+          ChromeUtils.getClassName(value) === type);
+}
+
+/**
+ * Convert any of several different representations of a date/time to a Date object.
+ * Accepts several formats:
+ * a Date object, an ISO8601 string, or a number of milliseconds since the epoch as
+ * either a number or a string.
+ *
+ * @param {Date|string|number} date
+ *      The date to convert.
+ * @returns {Date}
+ *      A Date object
+ */
+function normalizeTime(date) {
+  // Of all the formats we accept the "number of milliseconds since the epoch as a string"
+  // is an outlier, everything else can just be passed directly to the Date constructor.
+  return new Date((typeof date == "string" && /^\d+$/.test(date))
+                        ? parseInt(date, 10) : date);
+}
+
+function withHandlingUserInput(window, callable) {
+  let handle = getWinUtils(window).setHandlingUserInput(true);
+  try {
+    return callable();
+  } finally {
+    handle.destruct();
+  }
+}
+
+/**
+ * Defines a lazy getter for the given property on the given object. The
+ * first time the property is accessed, the return value of the getter
+ * is defined on the current `this` object with the given property name.
+ * Importantly, this means that a lazy getter defined on an object
+ * prototype will be invoked separately for each object instance that
+ * it's accessed on.
+ *
+ * @param {object} object
+ *        The prototype object on which to define the getter.
+ * @param {string|Symbol} prop
+ *        The property name for which to define the getter.
+ * @param {function} getter
+ *        The function to call in order to generate the final property
+ *        value.
+ */
+function defineLazyGetter(object, prop, getter) {
+  let redefine = (obj, value) => {
+    Object.defineProperty(obj, prop, {
+      enumerable: true,
+      configurable: true,
+      writable: true,
+      value,
+    });
+    return value;
+  };
+
+  Object.defineProperty(object, prop, {
+    enumerable: true,
+    configurable: true,
+
+    get() {
+      return redefine(this, getter.call(this));
+    },
+
+    set(value) {
+      redefine(this, value);
+    },
+  });
+}
+
+function checkLoadURL(url, principal, options) {
+  let ssm = Services.scriptSecurityManager;
+
+  let flags = ssm.STANDARD;
+  if (!options.allowScript) {
+    flags |= ssm.DISALLOW_SCRIPT;
+  }
+  if (!options.allowInheritsPrincipal) {
+    flags |= ssm.DISALLOW_INHERIT_PRINCIPAL;
+  }
+  if (options.dontReportErrors) {
+    flags |= ssm.DONT_REPORT_ERRORS;
+  }
+
+  try {
+    ssm.checkLoadURIWithPrincipal(principal,
+                                  Services.io.newURI(url),
+                                  flags);
+  } catch (e) {
+    return false;
+  }
+  return true;
+}
+
+function makeWidgetId(id) {
+  id = id.toLowerCase();
+  // FIXME: This allows for collisions.
+  return id.replace(/[^a-z0-9_-]/g, "_");
+}
+
 /**
  * A sentinel class to indicate that an array of values should be
  * treated as an array when used as a promise resolution value, but as a
@@ -85,12 +205,119 @@ class NoCloneSpreadArgs {
   }
 }
 
+const LISTENERS = Symbol("listeners");
+const ONCE_MAP = Symbol("onceMap");
+
+class EventEmitter {
+  constructor() {
+    this[LISTENERS] = new Map();
+    this[ONCE_MAP] = new WeakMap();
+  }
+
+  /**
+   * Adds the given function as a listener for the given event.
+   *
+   * The listener function may optionally return a Promise which
+   * resolves when it has completed all operations which event
+   * dispatchers may need to block on.
+   *
+   * @param {string} event
+   *       The name of the event to listen for.
+   * @param {function(string, ...any)} listener
+   *        The listener to call when events are emitted.
+   */
+  on(event, listener) {
+    let listeners = this[LISTENERS].get(event);
+    if (!listeners) {
+      listeners = new Set();
+      this[LISTENERS].set(event, listeners);
+    }
+
+    listeners.add(listener);
+  }
+
+  /**
+   * Removes the given function as a listener for the given event.
+   *
+   * @param {string} event
+   *       The name of the event to stop listening for.
+   * @param {function(string, ...any)} listener
+   *        The listener function to remove.
+   */
+  off(event, listener) {
+    let set = this[LISTENERS].get(event);
+    if (set) {
+      set.delete(listener);
+      set.delete(this[ONCE_MAP].get(listener));
+      if (!set.size) {
+        this[LISTENERS].delete(event);
+      }
+    }
+  }
+
+  /**
+   * Adds the given function as a listener for the given event once.
+   *
+   * @param {string} event
+   *       The name of the event to listen for.
+   * @param {function(string, ...any)} listener
+   *        The listener to call when events are emitted.
+   */
+  once(event, listener) {
+    let wrapper = (...args) => {
+      this.off(event, wrapper);
+      this[ONCE_MAP].delete(listener);
+
+      return listener(...args);
+    };
+    this[ONCE_MAP].set(listener, wrapper);
+
+    this.on(event, wrapper);
+  }
+
+
+  /**
+   * Triggers all listeners for the given event. If any listeners return
+   * a value, returns a promise which resolves when all returned
+   * promises have resolved. Otherwise, returns undefined.
+   *
+   * @param {string} event
+   *       The name of the event to emit.
+   * @param {any} args
+   *        Arbitrary arguments to pass to the listener functions, after
+   *        the event name.
+   * @returns {Promise?}
+   */
+  emit(event, ...args) {
+    let listeners = this[LISTENERS].get(event);
+
+    if (listeners) {
+      let promises = [];
+
+      for (let listener of listeners) {
+        try {
+          let result = listener(event, ...args);
+          if (result !== undefined) {
+            promises.push(result);
+          }
+        } catch (e) {
+          Cu.reportError(e);
+        }
+      }
+
+      if (promises.length) {
+        return Promise.all(promises);
+      }
+    }
+  }
+}
+
 /**
  * Base class for WebExtension APIs.  Each API creates a new class
  * that inherits from this class, the derived class is instantiated
  * once for each extension that uses the API.
  */
-class ExtensionAPI extends ExtensionUtils.EventEmitter {
+class ExtensionAPI extends EventEmitter {
   constructor(extension) {
     super();
 
@@ -246,7 +473,7 @@ class BaseContext {
       return true;
     }
 
-    return ExtensionUtils.checkLoadURL(url, this.principal, options);
+    return checkLoadURL(url, this.principal, options);
   }
 
   /**
@@ -2074,14 +2301,23 @@ ExtensionCommon = {
   CanOfAPIs,
   EventManager,
   ExtensionAPI,
+  EventEmitter,
   LocalAPIImplementation,
   LocaleData,
   NoCloneSpreadArgs,
   SchemaAPIInterface,
   SchemaAPIManager,
   SpreadArgs,
+  checkLoadURL,
+  defineLazyGetter,
+  getConsole,
   ignoreEvent,
+  instanceOf,
+  makeWidgetId,
+  normalizeTime,
+  runSafeSyncWithoutClone,
   stylesheetMap,
+  withHandlingUserInput,
 
   MultiAPIManager,
   LazyAPIManager,
diff --git a/toolkit/components/extensions/ExtensionContent.jsm b/toolkit/components/extensions/ExtensionContent.jsm
index 8320621bf6e8..a249136f4ebe 100644
--- a/toolkit/components/extensions/ExtensionContent.jsm
+++ b/toolkit/components/extensions/ExtensionContent.jsm
@@ -39,19 +39,19 @@ XPCOMUtils.defineLazyGlobalGetters(this, ["crypto", "TextEncoder"]);
 const {
   DefaultMap,
   DefaultWeakMap,
-  defineLazyGetter,
   getInnerWindowID,
   getWinUtils,
   promiseDocumentIdle,
   promiseDocumentLoaded,
   promiseDocumentReady,
-  runSafeSyncWithoutClone,
 } = ExtensionUtils;
 
 const {
   BaseContext,
   CanOfAPIs,
   SchemaAPIManager,
+  defineLazyGetter,
+  runSafeSyncWithoutClone,
 } = ExtensionCommon;
 
 const {
@@ -60,7 +60,7 @@ const {
   Messenger,
 } = ExtensionChild;
 
-XPCOMUtils.defineLazyGetter(this, "console", ExtensionUtils.getConsole);
+XPCOMUtils.defineLazyGetter(this, "console", ExtensionCommon.getConsole);
 
 
 var DocumentManager;
diff --git a/toolkit/components/extensions/ExtensionPageChild.jsm b/toolkit/components/extensions/ExtensionPageChild.jsm
index a45eac9a6ee5..2493f525e135 100644
--- a/toolkit/components/extensions/ExtensionPageChild.jsm
+++ b/toolkit/components/extensions/ExtensionPageChild.jsm
@@ -37,7 +37,6 @@ ChromeUtils.import("resource://gre/modules/ExtensionChild.jsm");
 ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
 
 const {
-  defineLazyGetter,
   getInnerWindowID,
   promiseEvent,
 } = ExtensionUtils;
@@ -46,6 +45,7 @@ const {
   BaseContext,
   CanOfAPIs,
   SchemaAPIManager,
+  defineLazyGetter,
 } = ExtensionCommon;
 
 const {
diff --git a/toolkit/components/extensions/ExtensionParent.jsm b/toolkit/components/extensions/ExtensionParent.jsm
index 0d0bb575f756..1a3647b9e2a4 100644
--- a/toolkit/components/extensions/ExtensionParent.jsm
+++ b/toolkit/components/extensions/ExtensionParent.jsm
@@ -25,8 +25,9 @@ XPCOMUtils.defineLazyModuleGetters(this, {
   E10SUtils: "resource://gre/modules/E10SUtils.jsm",
   ExtensionData: "resource://gre/modules/Extension.jsm",
   MessageChannel: "resource://gre/modules/MessageChannel.jsm",
-  OS: "resource://gre/modules/osfile.jsm",
+  MessageManagerProxy: "resource://gre/modules/MessageManagerProxy.jsm",
   NativeApp: "resource://gre/modules/NativeMessaging.jsm",
+  OS: "resource://gre/modules/osfile.jsm",
   PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.jsm",
   Schemas: "resource://gre/modules/Schemas.jsm",
 });
@@ -43,14 +44,13 @@ var {
   CanOfAPIs,
   SchemaAPIManager,
   SpreadArgs,
+  defineLazyGetter,
 } = ExtensionCommon;
 
 var {
   DefaultMap,
   DefaultWeakMap,
   ExtensionError,
-  MessageManagerProxy,
-  defineLazyGetter,
   promiseDocumentLoaded,
   promiseEvent,
   promiseObserved,
diff --git a/toolkit/components/extensions/ExtensionStorageSync.jsm b/toolkit/components/extensions/ExtensionStorageSync.jsm
index d7404ab94b84..02c8c05e1874 100644
--- a/toolkit/components/extensions/ExtensionStorageSync.jsm
+++ b/toolkit/components/extensions/ExtensionStorageSync.jsm
@@ -48,6 +48,7 @@ XPCOMUtils.defineLazyModuleGetters(this, {
   CollectionKeyManager: "resource://services-sync/record.js",
   CommonUtils: "resource://services-common/utils.js",
   CryptoUtils: "resource://services-crypto/utils.js",
+  ExtensionCommon: "resource://gre/modules/ExtensionCommon.jsm",
   fxAccounts: "resource://gre/modules/FxAccounts.jsm",
   KintoHttpClient: "resource://services-common/kinto-http-client.js",
   Kinto: "resource://services-common/kinto-offline-client.js",
@@ -68,7 +69,6 @@ XPCOMUtils.defineLazyGetter(this, "WeaveCrypto", function() {
 
 const {
   DefaultMap,
-  runSafeSyncWithoutClone,
 } = ExtensionUtils;
 
 // Map of Extensions to Set<Contexts> to track contexts that are still
@@ -1249,7 +1249,7 @@ class ExtensionStorageSync {
     let listeners = this.listeners.get(extension) || new Set();
     if (listeners) {
       for (let listener of listeners) {
-        runSafeSyncWithoutClone(listener, changes);
+        ExtensionCommon.runSafeSyncWithoutClone(listener, changes);
       }
     }
   }
diff --git a/toolkit/components/extensions/ExtensionTestCommon.jsm b/toolkit/components/extensions/ExtensionTestCommon.jsm
index 770c585cc692..8810d36c5070 100644
--- a/toolkit/components/extensions/ExtensionTestCommon.jsm
+++ b/toolkit/components/extensions/ExtensionTestCommon.jsm
@@ -33,6 +33,7 @@ ChromeUtils.defineModuleGetter(this, "OS",
 XPCOMUtils.defineLazyGetter(this, "apiManager",
                             () => ExtensionParent.apiManager);
 
+ChromeUtils.import("resource://gre/modules/ExtensionCommon.jsm");
 ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
 
 XPCOMUtils.defineLazyServiceGetter(this, "uuidGen",
@@ -41,10 +42,13 @@ XPCOMUtils.defineLazyServiceGetter(this, "uuidGen",
 
 const {
   flushJarCache,
-  instanceOf,
 } = ExtensionUtils;
 
-XPCOMUtils.defineLazyGetter(this, "console", ExtensionUtils.getConsole);
+const {
+  instanceOf,
+} = ExtensionCommon;
+
+XPCOMUtils.defineLazyGetter(this, "console", () => ExtensionCommon.getConsole());
 
 
 /**
diff --git a/toolkit/components/extensions/ExtensionUtils.jsm b/toolkit/components/extensions/ExtensionUtils.jsm
index 9ad1776175b7..3d00a4490052 100644
--- a/toolkit/components/extensions/ExtensionUtils.jsm
+++ b/toolkit/components/extensions/ExtensionUtils.jsm
@@ -10,20 +10,9 @@ var EXPORTED_SYMBOLS = ["ExtensionUtils"];
 ChromeUtils.import("resource://gre/modules/Services.jsm");
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
 
-ChromeUtils.defineModuleGetter(this, "ConsoleAPI",
-                               "resource://gre/modules/Console.jsm");
 ChromeUtils.defineModuleGetter(this, "setTimeout",
                                "resource://gre/modules/Timer.jsm");
 
-function getConsole() {
-  return new ConsoleAPI({
-    maxLogLevelPref: "extensions.webextensions.log.level",
-    prefix: "WebExtensions",
-  });
-}
-
-XPCOMUtils.defineLazyGetter(this, "console", getConsole);
-
 // xpcshell doesn't handle idle callbacks well.
 XPCOMUtils.defineLazyGetter(this, "idleTimeout",
                             () => Services.appinfo.name === "XPCShell" ? 500 : undefined);
@@ -62,23 +51,6 @@ function filterStack(error) {
   return String(error.stack).replace(/(^.*(Task\.jsm|Promise-backend\.js).*\n)+/gm, "<Promise Chain>\n");
 }
 
-// Run a function and report exceptions.
-function runSafeSyncWithoutClone(f, ...args) {
-  try {
-    return f(...args);
-  } catch (e) {
-    dump(`Extension error: ${e} ${e.fileName} ${e.lineNumber}\n[[Exception stack\n${filterStack(e)}Current stack\n${filterStack(Error())}]]\n`);
-    Cu.reportError(e);
-  }
-}
-
-// Return true if the given value is an instance of the given
-// native type.
-function instanceOf(value, type) {
-  return (value && typeof value === "object" &&
-          ChromeUtils.getClassName(value) === type);
-}
-
 /**
  * Similar to a WeakMap, but creates a new key with the given
  * constructor if one is not present.
@@ -129,122 +101,6 @@ function getInnerWindowID(window) {
   return getWinUtils(window).currentInnerWindowID;
 }
 
-function withHandlingUserInput(window, callable) {
-  let handle = getWinUtils(window).setHandlingUserInput(true);
-  try {
-    return callable();
-  } finally {
-    handle.destruct();
-  }
-}
-
-const LISTENERS = Symbol("listeners");
-const ONCE_MAP = Symbol("onceMap");
-
-class EventEmitter {
-  constructor() {
-    this[LISTENERS] = new Map();
-    this[ONCE_MAP] = new WeakMap();
-  }
-
-  /**
-   * Adds the given function as a listener for the given event.
-   *
-   * The listener function may optionally return a Promise which
-   * resolves when it has completed all operations which event
-   * dispatchers may need to block on.
-   *
-   * @param {string} event
-   *       The name of the event to listen for.
-   * @param {function(string, ...any)} listener
-   *        The listener to call when events are emitted.
-   */
-  on(event, listener) {
-    let listeners = this[LISTENERS].get(event);
-    if (!listeners) {
-      listeners = new Set();
-      this[LISTENERS].set(event, listeners);
-    }
-
-    listeners.add(listener);
-  }
-
-  /**
-   * Removes the given function as a listener for the given event.
-   *
-   * @param {string} event
-   *       The name of the event to stop listening for.
-   * @param {function(string, ...any)} listener
-   *        The listener function to remove.
-   */
-  off(event, listener) {
-    let set = this[LISTENERS].get(event);
-    if (set) {
-      set.delete(listener);
-      set.delete(this[ONCE_MAP].get(listener));
-      if (!set.size) {
-        this[LISTENERS].delete(event);
-      }
-    }
-  }
-
-  /**
-   * Adds the given function as a listener for the given event once.
-   *
-   * @param {string} event
-   *       The name of the event to listen for.
-   * @param {function(string, ...any)} listener
-   *        The listener to call when events are emitted.
-   */
-  once(event, listener) {
-    let wrapper = (...args) => {
-      this.off(event, wrapper);
-      this[ONCE_MAP].delete(listener);
-
-      return listener(...args);
-    };
-    this[ONCE_MAP].set(listener, wrapper);
-
-    this.on(event, wrapper);
-  }
-
-
-  /**
-   * Triggers all listeners for the given event. If any listeners return
-   * a value, returns a promise which resolves when all returned
-   * promises have resolved. Otherwise, returns undefined.
-   *
-   * @param {string} event
-   *       The name of the event to emit.
-   * @param {any} args
-   *        Arbitrary arguments to pass to the listener functions, after
-   *        the event name.
-   * @returns {Promise?}
-   */
-  emit(event, ...args) {
-    let listeners = this[LISTENERS].get(event);
-
-    if (listeners) {
-      let promises = [];
-
-      for (let listener of listeners) {
-        try {
-          let result = listener(event, ...args);
-          if (result !== undefined) {
-            promises.push(result);
-          }
-        } catch (e) {
-          Cu.reportError(e);
-        }
-      }
-
-      if (promises.length) {
-        return Promise.all(promises);
-      }
-    }
-  }
-}
-
 /**
  * A set with a limited number of slots, which flushes older entries as
  * newer ones are added.
@@ -404,303 +260,21 @@ function flushJarCache(jarPath) {
   Services.obs.notifyObservers(null, "flush-cache-entry", jarPath);
 }
 
-/**
- * Convert any of several different representations of a date/time to a Date object.
- * Accepts several formats:
- * a Date object, an ISO8601 string, or a number of milliseconds since the epoch as
- * either a number or a string.
- *
- * @param {Date|string|number} date
- *      The date to convert.
- * @returns {Date}
- *      A Date object
- */
-function normalizeTime(date) {
-  // Of all the formats we accept the "number of milliseconds since the epoch as a string"
-  // is an outlier, everything else can just be passed directly to the Date constructor.
-  return new Date((typeof date == "string" && /^\d+$/.test(date))
-                        ? parseInt(date, 10) : date);
-}
-
-/**
- * Defines a lazy getter for the given property on the given object. The
- * first time the property is accessed, the return value of the getter
- * is defined on the current `this` object with the given property name.
- * Importantly, this means that a lazy getter defined on an object
- * prototype will be invoked separately for each object instance that
- * it's accessed on.
- *
- * @param {object} object
- *        The prototype object on which to define the getter.
- * @param {string|Symbol} prop
- *        The property name for which to define the getter.
- * @param {function} getter
- *        The function to call in order to generate the final property
- *        value.
- */
-function defineLazyGetter(object, prop, getter) {
-  let redefine = (obj, value) => {
-    Object.defineProperty(obj, prop, {
-      enumerable: true,
-      configurable: true,
-      writable: true,
-      value,
-    });
-    return value;
-  };
-
-  Object.defineProperty(object, prop, {
-    enumerable: true,
-    configurable: true,
-
-    get() {
-      return redefine(this, getter.call(this));
-    },
-
-    set(value) {
-      redefine(this, value);
-    },
-  });
-}
-
-/**
- * Acts as a proxy for a message manager or message manager owner, and
- * tracks docShell swaps so that messages are always sent to the same
- * receiver, even if it is moved to a different <browser>.
- *
- * @param {nsIMessageSender|Element} target
- *        The target message manager on which to send messages, or the
- *        <browser> element which owns it.
- */
-class MessageManagerProxy {
-  constructor(target) {
-    this.listeners = new DefaultMap(() => new Map());
-    this.closed = false;
-
-    if (target instanceof Ci.nsIMessageSender) {
-      this.messageManager = target;
-    } else {
-      this.addListeners(target);
-    }
-
-    Services.obs.addObserver(this, "message-manager-close");
-  }
-
-  /**
-   * Disposes of the proxy object, removes event listeners, and drops
-   * all references to the underlying message manager.
-   *
-   * Must be called before the last reference to the proxy is dropped,
-   * unless the underlying message manager or <browser> is also being
-   * destroyed.
-   */
-  dispose() {
-    if (this.eventTarget) {
-      this.removeListeners(this.eventTarget);
-      this.eventTarget = null;
-    }
-    this.messageManager = null;
-
-    Services.obs.removeObserver(this, "message-manager-close");
-  }
-
-  observe(subject, topic, data) {
-    if (topic === "message-manager-close") {
-      if (subject === this.messageManager) {
-        this.closed = true;
-      }
-    }
-  }
-
-  /**
-   * Returns true if the given target is the same as, or owns, the given
-   * message manager.
-   *
-   * @param {nsIMessageSender|MessageManagerProxy|Element} target
-   *        The message manager, MessageManagerProxy, or <browser>
-   *        element against which to match.
-   * @param {nsIMessageSender} messageManager
-   *        The message manager against which to match `target`.
-   *
-   * @returns {boolean}
-   *        True if `messageManager` is the same object as `target`, or
-   *        `target` is a MessageManagerProxy or <browser> element that
-   *        is tied to it.
-   */
-  static matches(target, messageManager) {
-    return target === messageManager || target.messageManager === messageManager;
-  }
-
-  /**
-   * @property {nsIMessageSender|null} messageManager
-   *        The message manager that is currently being proxied. This
-   *        may change during the life of the proxy object, so should
-   *        not be stored elsewhere.
-   */
-
-  /**
-   * Sends a message on the proxied message manager.
-   *
-   * @param {array} args
-   *        Arguments to be passed verbatim to the underlying
-   *        sendAsyncMessage method.
-   * @returns {undefined}
-   */
-  sendAsyncMessage(...args) {
-    if (this.messageManager) {
-      return this.messageManager.sendAsyncMessage(...args);
-    }
-
-    Cu.reportError(`Cannot send message: Other side disconnected: ${uneval(args)}`);
-  }
-
-  get isDisconnected() {
-    return this.closed || !this.messageManager;
-  }
-
-  /**
-   * Adds a message listener to the current message manager, and
-   * transfers it to the new message manager after a docShell swap.
-   *
-   * @param {string} message
-   *        The name of the message to listen for.
-   * @param {nsIMessageListener} listener
-   *        The listener to add.
-   * @param {boolean} [listenWhenClosed = false]
-   *        If true, the listener will receive messages which were sent
-   *        after the remote side of the listener began closing.
-   */
-  addMessageListener(message, listener, listenWhenClosed = false) {
-    this.messageManager.addMessageListener(message, listener, listenWhenClosed);
-    this.listeners.get(message).set(listener, listenWhenClosed);
-  }
-
-  /**
-   * Adds a message listener from the current message manager.
-   *
-   * @param {string} message
-   *        The name of the message to stop listening for.
-   * @param {nsIMessageListener} listener
-   *        The listener to remove.
-   */
-  removeMessageListener(message, listener) {
-    this.messageManager.removeMessageListener(message, listener);
-
-    let listeners = this.listeners.get(message);
-    listeners.delete(listener);
-    if (!listeners.size) {
-      this.listeners.delete(message);
-    }
-  }
-
-  /**
-   * @private
-   * Iterates over all of the currently registered message listeners.
-   */
-  * iterListeners() {
-    for (let [message, listeners] of this.listeners) {
-      for (let [listener, listenWhenClosed] of listeners) {
-        yield {message, listener, listenWhenClosed};
-      }
-    }
-  }
-
-  /**
-   * @private
-   * Adds docShell swap listeners to the message manager owner.
-   *
-   * @param {Element} target
-   *        The target element.
-   */
-  addListeners(target) {
-    target.addEventListener("SwapDocShells", this);
-
-    this.eventTarget = target;
-    this.messageManager = target.messageManager;
-
-    for (let {message, listener, listenWhenClosed} of this.iterListeners()) {
-      this.messageManager.addMessageListener(message, listener, listenWhenClosed);
-    }
-  }
-
-  /**
-   * @private
-   * Removes docShell swap listeners to the message manager owner.
-   *
-   * @param {Element} target
-   *        The target element.
-   */
-  removeListeners(target) {
-    target.removeEventListener("SwapDocShells", this);
-
-    for (let {message, listener} of this.iterListeners()) {
-      this.messageManager.removeMessageListener(message, listener);
-    }
-  }
-
-  handleEvent(event) {
-    if (event.type == "SwapDocShells") {
-      this.removeListeners(this.eventTarget);
-      this.addListeners(event.detail);
-    }
-  }
-}
-
-function checkLoadURL(url, principal, options) {
-  let ssm = Services.scriptSecurityManager;
-
-  let flags = ssm.STANDARD;
-  if (!options.allowScript) {
-    flags |= ssm.DISALLOW_SCRIPT;
-  }
-  if (!options.allowInheritsPrincipal) {
-    flags |= ssm.DISALLOW_INHERIT_PRINCIPAL;
-  }
-  if (options.dontReportErrors) {
-    flags |= ssm.DONT_REPORT_ERRORS;
-  }
-
-  try {
-    ssm.checkLoadURIWithPrincipal(principal,
-                                  Services.io.newURI(url),
-                                  flags);
-  } catch (e) {
-    return false;
-  }
-  return true;
-}
-
-function makeWidgetId(id) {
-  id = id.toLowerCase();
-  // FIXME: This allows for collisions.
-  return id.replace(/[^a-z0-9_-]/g, "_");
-}
-
 var ExtensionUtils = {
-  checkLoadURL,
-  defineLazyGetter,
   flushJarCache,
-  getConsole,
   getInnerWindowID,
   getMessageManager,
   getUniqueId,
   filterStack,
   getWinUtils,
-  instanceOf,
-  makeWidgetId,
-  normalizeTime,
   promiseDocumentIdle,
   promiseDocumentLoaded,
   promiseDocumentReady,
   promiseEvent,
   promiseObserved,
   promiseTimeout,
-  runSafeSyncWithoutClone,
-  withHandlingUserInput,
   DefaultMap,
   DefaultWeakMap,
-  EventEmitter,
   ExtensionError,
   LimitedSet,
-  MessageManagerProxy,
 };
diff --git a/toolkit/components/extensions/MessageChannel.jsm b/toolkit/components/extensions/MessageChannel.jsm
index f6bdb9413c67..49e1ce63329e 100644
--- a/toolkit/components/extensions/MessageChannel.jsm
+++ b/toolkit/components/extensions/MessageChannel.jsm
@@ -105,9 +105,19 @@ ChromeUtils.import("resource://gre/modules/AppConstants.jsm");
 ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
 ChromeUtils.import("resource://gre/modules/Services.jsm");
 
-const {
-  MessageManagerProxy,
-} = ExtensionUtils;
+ChromeUtils.defineModuleGetter(this, "MessageManagerProxy",
+                               "resource://gre/modules/MessageManagerProxy.jsm");
+
+function getMessageManager(target) {
+  if (typeof target.sendAsyncMessage === "function") {
+    return target;
+  }
+  return new MessageManagerProxy(target);
+}
+
+function matches(target, messageManager) {
+  return target === messageManager || target.messageManager === messageManager;
+}
 
 const {DEBUG} = AppConstants;
 
@@ -919,7 +929,7 @@ this.MessageChannel = {
       return;
     }
 
-    let target = new MessageManagerProxy(data.target);
+    let target = getMessageManager(data.target);
 
     let deferred = {
       sender: data.sender,
@@ -930,7 +940,9 @@ this.MessageChannel = {
 
     let cleanup = () => {
       this.pendingResponses.delete(deferred);
-      target.dispose();
+      if (target.dispose) {
+        target.dispose();
+      }
     };
     this.pendingResponses.add(deferred);
 
@@ -1078,7 +1090,7 @@ this.MessageChannel = {
    */
   abortMessageManager(target, reason) {
     for (let response of this.pendingResponses) {
-      if (MessageManagerProxy.matches(response.messageManager, target)) {
+      if (matches(response.messageManager, target)) {
         this.abortedResponses.add(response.channelId);
         response.reject(reason);
       }
diff --git a/toolkit/components/extensions/MessageManagerProxy.jsm b/toolkit/components/extensions/MessageManagerProxy.jsm
new file mode 100644
index 000000000000..e35b96b64746
--- /dev/null
+++ b/toolkit/components/extensions/MessageManagerProxy.jsm
@@ -0,0 +1,198 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+/* 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";
+
+var EXPORTED_SYMBOLS = ["MessageManagerProxy"];
+
+ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+const {
+  DefaultMap,
+} = ExtensionUtils;
+
+/**
+ * Acts as a proxy for a message manager or message manager owner, and
+ * tracks docShell swaps so that messages are always sent to the same
+ * receiver, even if it is moved to a different <browser>.
+ *
+ * @param {nsIMessageSender|Element} target
+ *        The target message manager on which to send messages, or the
+ *        <browser> element which owns it.
+ */
+class MessageManagerProxy {
+  constructor(target) {
+    this.listeners = new DefaultMap(() => new Map());
+    this.closed = false;
+
+    if (target instanceof Ci.nsIMessageSender) {
+      this.messageManager = target;
+    } else {
+      this.addListeners(target);
+    }
+
+    Services.obs.addObserver(this, "message-manager-close");
+  }
+
+  /**
+   * Disposes of the proxy object, removes event listeners, and drops
+   * all references to the underlying message manager.
+   *
+   * Must be called before the last reference to the proxy is dropped,
+   * unless the underlying message manager or <browser> is also being
+   * destroyed.
+   */
+  dispose() {
+    if (this.eventTarget) {
+      this.removeListeners(this.eventTarget);
+      this.eventTarget = null;
+    }
+    this.messageManager = null;
+
+    Services.obs.removeObserver(this, "message-manager-close");
+  }
+
+  observe(subject, topic, data) {
+    if (topic === "message-manager-close") {
+      if (subject === this.messageManager) {
+        this.closed = true;
+      }
+    }
+  }
+
+  /**
+   * Returns true if the given target is the same as, or owns, the given
+   * message manager.
+   *
+   * @param {nsIMessageSender|MessageManagerProxy|Element} target
+   *        The message manager, MessageManagerProxy, or <browser>
+   *        element against which to match.
+   * @param {nsIMessageSender} messageManager
+   *        The message manager against which to match `target`.
+   *
+   * @returns {boolean}
+   *        True if `messageManager` is the same object as `target`, or
+   *        `target` is a MessageManagerProxy or <browser> element that
+   *        is tied to it.
+   */
+  static matches(target, messageManager) {
+    return target === messageManager || target.messageManager === messageManager;
+  }
+
+  /**
+   * @property {nsIMessageSender|null} messageManager
+   *        The message manager that is currently being proxied. This
+   *        may change during the life of the proxy object, so should
+   *        not be stored elsewhere.
+   */
+
+  /**
+   * Sends a message on the proxied message manager.
+   *
+   * @param {array} args
+   *        Arguments to be passed verbatim to the underlying
+   *        sendAsyncMessage method.
+   * @returns {undefined}
+   */
+  sendAsyncMessage(...args) {
+    if (this.messageManager) {
+      return this.messageManager.sendAsyncMessage(...args);
+    }
+
+    Cu.reportError(`Cannot send message: Other side disconnected: ${uneval(args)}`);
+  }
+
+  get isDisconnected() {
+    return this.closed || !this.messageManager;
+  }
+
+  /**
+   * Adds a message listener to the current message manager, and
+   * transfers it to the new message manager after a docShell swap.
+   *
+   * @param {string} message
+   *        The name of the message to listen for.
+   * @param {nsIMessageListener} listener
+   *        The listener to add.
+   * @param {boolean} [listenWhenClosed = false]
+   *        If true, the listener will receive messages which were sent
+   *        after the remote side of the listener began closing.
+   */
+  addMessageListener(message, listener, listenWhenClosed = false) {
+    this.messageManager.addMessageListener(message, listener, listenWhenClosed);
+    this.listeners.get(message).set(listener, listenWhenClosed);
+  }
+
+  /**
+   * Adds a message listener from the current message manager.
+   *
+   * @param {string} message
+   *        The name of the message to stop listening for.
+   * @param {nsIMessageListener} listener
+   *        The listener to remove.
+   */
+  removeMessageListener(message, listener) {
+    this.messageManager.removeMessageListener(message, listener);
+
+    let listeners = this.listeners.get(message);
+    listeners.delete(listener);
+    if (!listeners.size) {
+      this.listeners.delete(message);
+    }
+  }
+
+  /**
+   * @private
+   * Iterates over all of the currently registered message listeners.
+   */
+  * iterListeners() {
+    for (let [message, listeners] of this.listeners) {
+      for (let [listener, listenWhenClosed] of listeners) {
+        yield {message, listener, listenWhenClosed};
+      }
+    }
+  }
+
+  /**
+   * @private
+   * Adds docShell swap listeners to the message manager owner.
+   *
+   * @param {Element} target
+   *        The target element.
+   */
+  addListeners(target) {
+    target.addEventListener("SwapDocShells", this);
+
+    this.eventTarget = target;
+    this.messageManager = target.messageManager;
+
+    for (let {message, listener, listenWhenClosed} of this.iterListeners()) {
+      this.messageManager.addMessageListener(message, listener, listenWhenClosed);
+    }
+  }
+
+  /**
+   * @private
+   * Removes docShell swap listeners to the message manager owner.
+   *
+   * @param {Element} target
+   *        The target element.
+   */
+  removeListeners(target) {
+    target.removeEventListener("SwapDocShells", this);
+
+    for (let {message, listener} of this.iterListeners()) {
+      this.messageManager.removeMessageListener(message, listener);
+    }
+  }
+
+  handleEvent(event) {
+    if (event.type == "SwapDocShells") {
+      this.removeListeners(this.eventTarget);
+      this.addListeners(event.detail);
+    }
+  }
+}
diff --git a/toolkit/components/extensions/ProxyScriptContext.jsm b/toolkit/components/extensions/ProxyScriptContext.jsm
index 8a483c148856..748870528251 100644
--- a/toolkit/components/extensions/ProxyScriptContext.jsm
+++ b/toolkit/components/extensions/ProxyScriptContext.jsm
@@ -38,7 +38,6 @@ const PROXY_TIMEOUT_SEC = 10;
 
 const {
   ExtensionError,
-  defineLazyGetter,
 } = ExtensionUtils;
 
 const {
@@ -46,6 +45,7 @@ const {
   CanOfAPIs,
   LocalAPIImplementation,
   SchemaAPIManager,
+  defineLazyGetter,
 } = ExtensionCommon;
 
 const PROXY_TYPES = Object.freeze({
diff --git a/toolkit/components/extensions/extension-process-script.js b/toolkit/components/extensions/extension-process-script.js
index 8fc3309f9873..53d1e44e0eeb 100644
--- a/toolkit/components/extensions/extension-process-script.js
+++ b/toolkit/components/extensions/extension-process-script.js
@@ -16,13 +16,14 @@ ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
 
 XPCOMUtils.defineLazyModuleGetters(this, {
   ExtensionChild: "resource://gre/modules/ExtensionChild.jsm",
+  ExtensionCommon: "resource://gre/modules/ExtensionCommon.jsm",
   ExtensionContent: "resource://gre/modules/ExtensionContent.jsm",
   ExtensionPageChild: "resource://gre/modules/ExtensionPageChild.jsm",
 });
 
 ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
 
-XPCOMUtils.defineLazyGetter(this, "console", () => ExtensionUtils.getConsole());
+XPCOMUtils.defineLazyGetter(this, "console", () => ExtensionCommon.getConsole());
 
 const {
   DefaultWeakMap,
diff --git a/toolkit/components/extensions/moz.build b/toolkit/components/extensions/moz.build
index 692821ab0e73..ccdfb4c206b7 100644
--- a/toolkit/components/extensions/moz.build
+++ b/toolkit/components/extensions/moz.build
@@ -26,6 +26,7 @@ EXTRA_JS_MODULES += [
     'FindContent.jsm',
     'LegacyExtensionsUtils.jsm',
     'MessageChannel.jsm',
+    'MessageManagerProxy.jsm',
     'NativeManifests.jsm',
     'NativeMessaging.jsm',
     'ProxyScriptContext.jsm',
diff --git a/toolkit/components/extensions/parent/ext-downloads.js b/toolkit/components/extensions/parent/ext-downloads.js
index 650c9effdc00..5d800eac5799 100644
--- a/toolkit/components/extensions/parent/ext-downloads.js
+++ b/toolkit/components/extensions/parent/ext-downloads.js
@@ -13,10 +13,6 @@ ChromeUtils.defineModuleGetter(this, "FileUtils",
 
 var {
   EventEmitter,
-  normalizeTime,
-} = ExtensionUtils;
-
-var {
   ignoreEvent,
 } = ExtensionCommon;
 
@@ -262,7 +258,7 @@ const downloadQuery = query => {
     if (arg == null) {
       return before ? Number.MAX_VALUE : 0;
     }
-    return normalizeTime(arg).getTime();
+    return ExtensionCommon.normalizeTime(arg).getTime();
   }
 
   const startedBefore = normalizeDownloadTime(query.startedBefore, true);
diff --git a/toolkit/components/extensions/parent/ext-idle.js b/toolkit/components/extensions/parent/ext-idle.js
index 5dcb2aaee507..b28f0a02fb9b 100644
--- a/toolkit/components/extensions/parent/ext-idle.js
+++ b/toolkit/components/extensions/parent/ext-idle.js
@@ -32,7 +32,7 @@ const getIdleObserver = (extension, context) => {
   let observerInfo = getIdleObserverInfo(extension, context);
   let {observer, detectionInterval} = observerInfo;
   if (!observer) {
-    observer = new class extends ExtensionUtils.EventEmitter {
+    observer = new class extends ExtensionCommon.EventEmitter {
       observe(subject, topic, data) {
         if (topic == "idle" || topic == "active") {
           this.emit("stateChanged", topic);
diff --git a/toolkit/components/extensions/parent/ext-management.js b/toolkit/components/extensions/parent/ext-management.js
index 620ab036956d..420240b6baf6 100644
--- a/toolkit/components/extensions/parent/ext-management.js
+++ b/toolkit/components/extensions/parent/ext-management.js
@@ -95,7 +95,7 @@ function checkAllowedAddon(addon) {
   return allowedTypes.includes(addon.type);
 }
 
-class AddonListener extends ExtensionUtils.EventEmitter {
+class AddonListener extends ExtensionCommon.EventEmitter {
   constructor() {
     super();
     AddonManager.addAddonListener(this);
diff --git a/toolkit/components/extensions/parent/ext-tabs-base.js b/toolkit/components/extensions/parent/ext-tabs-base.js
index 6891b8299be5..e632a92b29c5 100644
--- a/toolkit/components/extensions/parent/ext-tabs-base.js
+++ b/toolkit/components/extensions/parent/ext-tabs-base.js
@@ -18,10 +18,13 @@ var {
   DefaultMap,
   DefaultWeakMap,
   ExtensionError,
-  defineLazyGetter,
   getWinUtils,
 } = ExtensionUtils;
 
+var {
+  defineLazyGetter,
+} = ExtensionCommon;
+
 /**
  * The platform-specific type of native tab objects, which are wrapped by
  * TabBase instances.
diff --git a/toolkit/components/extensions/parent/ext-toolkit.js b/toolkit/components/extensions/parent/ext-toolkit.js
index 9b1494f5ad8c..5a4c943f9c40 100644
--- a/toolkit/components/extensions/parent/ext-toolkit.js
+++ b/toolkit/components/extensions/parent/ext-toolkit.js
@@ -19,7 +19,7 @@ XPCOMUtils.defineLazyGlobalGetters(this, ["URL"]);
 
 ChromeUtils.import("resource://gre/modules/ExtensionCommon.jsm");
 
-global.EventEmitter = ExtensionUtils.EventEmitter;
+global.EventEmitter = ExtensionCommon.EventEmitter;
 global.EventManager = ExtensionCommon.EventManager;
 
 /* globals DEFAULT_STORE, PRIVATE_STORE, CONTAINER_STORE */