--- a/.eslintignore
+++ b/.eslintignore
@@ -93,17 +93,16 @@ devtools/client/framework/**
 !devtools/client/framework/toolbox*
 devtools/client/inspector/markup/test/doc_markup_events_*.html
 devtools/client/inspector/rules/test/doc_media_queries.html
 devtools/client/memory/test/chrome/*.html
 devtools/client/performance/components/test/test_jit_optimizations_01.html
 devtools/client/projecteditor/**
 devtools/client/responsive.html/test/browser/touch.html
 devtools/client/responsivedesign/**
-!devtools/client/responsivedesign/responsivedesign.jsm
 devtools/client/scratchpad/**
 devtools/client/shadereditor/**
 devtools/client/shared/*.jsm
 devtools/client/shared/components/reps/reps.js
 devtools/client/shared/components/reps/test/mochitest/*.html
 !devtools/client/shared/components/reps/test/mochitest/test_reps_infinity.html
 !devtools/client/shared/components/reps/test/mochitest/test_reps_nan.html
 !devtools/client/shared/components/reps/test/mochitest/test_reps_promise.html

--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -8465,22 +8465,16 @@ XPCOMUtils.defineLazyGetter(Scratchpad, 
 });
 
 var ResponsiveUI = {
   toggle: function RUI_toggle() {
     this.ResponsiveUIManager.toggle(window, gBrowser.selectedTab);
   }
 };
 
-XPCOMUtils.defineLazyGetter(ResponsiveUI, "ResponsiveUIManager", function() {
-  let tmp = {};
-  Cu.import("resource://devtools/client/responsivedesign/responsivedesign.jsm", tmp);
-  return tmp.ResponsiveUIManager;
-});
-
 var MousePosTracker = {
   _listeners: new Set(),
   _x: 0,
   _y: 0,
   get _windowUtils() {
     delete this._windowUtils;
     return this._windowUtils = window.getInterface(Ci.nsIDOMWindowUtils);
   },

--- a/devtools/bootstrap.js
+++ b/devtools/bootstrap.js
@@ -205,17 +205,16 @@ function unload(reason) {
   // to be converted into regular modules
   Cu.unload("resource://devtools/client/shared/browser-loader.js");
   Cu.unload("resource://devtools/client/framework/ToolboxProcess.jsm");
   Cu.unload("resource://devtools/shared/apps/Devices.jsm");
   Cu.unload("resource://devtools/client/scratchpad/scratchpad-manager.jsm");
   Cu.unload("resource://devtools/shared/Parser.jsm");
   Cu.unload("resource://devtools/client/shared/DOMHelpers.jsm");
   Cu.unload("resource://devtools/client/shared/widgets/VariablesView.jsm");
-  Cu.unload("resource://devtools/client/responsivedesign/responsivedesign.jsm");
   Cu.unload("resource://devtools/client/shared/widgets/AbstractTreeItem.jsm");
   Cu.unload("resource://devtools/shared/deprecated-sync-thenables.js");
 }
 
 function reload(event) {
   // We automatically reload the toolbox if we are on a browser tab
   // with a toolbox already opened
   let reloadToolbox = false;

--- a/devtools/client/definitions.js
+++ b/devtools/client/definitions.js
@@ -22,17 +22,17 @@ loader.lazyGetter(this, "PerformancePane
 loader.lazyGetter(this, "NetMonitorPanel", () => require("devtools/client/netmonitor/panel").NetMonitorPanel);
 loader.lazyGetter(this, "StoragePanel", () => require("devtools/client/storage/panel").StoragePanel);
 loader.lazyGetter(this, "ScratchpadPanel", () => require("devtools/client/scratchpad/scratchpad-panel").ScratchpadPanel);
 loader.lazyGetter(this, "DomPanel", () => require("devtools/client/dom/dom-panel").DomPanel);
 
 // Other dependencies
 loader.lazyRequireGetter(this, "CommandUtils", "devtools/client/shared/developer-toolbar", true);
 loader.lazyRequireGetter(this, "CommandState", "devtools/shared/gcli/command-state", true);
-loader.lazyImporter(this, "ResponsiveUIManager", "resource://devtools/client/responsivedesign/responsivedesign.jsm");
+loader.lazyRequireGetter(this, "ResponsiveUIManager", "devtools/client/responsivedesign/responsivedesign");
 loader.lazyImporter(this, "ScratchpadManager", "resource://devtools/client/scratchpad/scratchpad-manager.jsm");
 
 const {MultiLocalizationHelper} = require("devtools/shared/l10n");
 const L10N = new MultiLocalizationHelper(
   "devtools/client/locales/startup.properties",
   "devtools/shim/locales/key-shortcuts.properties"
 );
 

--- a/devtools/client/framework/devtools-browser.js
+++ b/devtools/client/framework/devtools-browser.js
@@ -20,18 +20,18 @@ const {gDevTools} = require("./devtools"
 // Load target and toolbox lazily as they need gDevTools to be fully initialized
 loader.lazyRequireGetter(this, "TargetFactory", "devtools/client/framework/target", true);
 loader.lazyRequireGetter(this, "Toolbox", "devtools/client/framework/toolbox", true);
 loader.lazyRequireGetter(this, "DebuggerServer", "devtools/server/main", true);
 loader.lazyRequireGetter(this, "DebuggerClient", "devtools/shared/client/main", true);
 loader.lazyRequireGetter(this, "BrowserMenus", "devtools/client/framework/browser-menus");
 loader.lazyRequireGetter(this, "appendStyleSheet", "devtools/client/shared/stylesheet-utils", true);
 loader.lazyRequireGetter(this, "DeveloperToolbar", "devtools/client/shared/developer-toolbar", true);
+loader.lazyRequireGetter(this, "ResponsiveUIManager", "devtools/client/responsivedesign/responsivedesign");
 loader.lazyImporter(this, "BrowserToolboxProcess", "resource://devtools/client/framework/ToolboxProcess.jsm");
-loader.lazyImporter(this, "ResponsiveUIManager", "resource://devtools/client/responsivedesign/responsivedesign.jsm");
 loader.lazyImporter(this, "ScratchpadManager", "resource://devtools/client/scratchpad/scratchpad-manager.jsm");
 
 loader.lazyImporter(this, "CustomizableUI", "resource:///modules/CustomizableUI.jsm");
 loader.lazyImporter(this, "CustomizableWidgets", "resource:///modules/CustomizableWidgets.jsm");
 loader.lazyImporter(this, "AppConstants", "resource://gre/modules/AppConstants.jsm");
 
 const {LocalizationHelper} = require("devtools/shared/l10n");
 const L10N = new LocalizationHelper("devtools/client/locales/toolbox.properties");

--- a/devtools/client/menus.js
+++ b/devtools/client/menus.js
@@ -26,19 +26,19 @@
  * - checkbox:
  *   If true, the menuitem is prefixed by a checkbox and runtime code can
  *   toggle it.
  */
 
 loader.lazyRequireGetter(this, "gDevToolsBrowser", "devtools/client/framework/devtools-browser", true);
 loader.lazyRequireGetter(this, "CommandUtils", "devtools/client/shared/developer-toolbar", true);
 loader.lazyRequireGetter(this, "TargetFactory", "devtools/client/framework/target", true);
+loader.lazyRequireGetter(this, "ResponsiveUIManager", "devtools/client/responsivedesign/responsivedesign");
 
 loader.lazyImporter(this, "BrowserToolboxProcess", "resource://devtools/client/framework/ToolboxProcess.jsm");
-loader.lazyImporter(this, "ResponsiveUIManager", "resource://devtools/client/responsivedesign/responsivedesign.jsm");
 loader.lazyImporter(this, "ScratchpadManager", "resource://devtools/client/scratchpad/scratchpad-manager.jsm");
 
 exports.menuitems = [
   { id: "menu_devToolbox",
     l10nKey: "devToolboxMenuItem",
     oncommand(event) {
       let window = event.target.ownerDocument.defaultView;
       gDevToolsBrowser.toggleToolboxCommand(window.gBrowser);

--- a/devtools/client/responsive.html/test/browser/head.js
+++ b/devtools/client/responsive.html/test/browser/head.js
@@ -58,17 +58,17 @@ registerCleanupFunction(() => {
   Services.prefs.clearUserPref("devtools.devices.url");
   Services.prefs.clearUserPref("devtools.responsive.html.enabled");
   Services.prefs.clearUserPref("devtools.responsive.html.displayedDeviceList");
   asyncStorage.removeItem("devtools.devices.url_cache");
   asyncStorage.removeItem("devtools.devices.local");
 });
 
 // This depends on the "devtools.responsive.html.enabled" pref
-const { ResponsiveUIManager } = require("resource://devtools/client/responsivedesign/responsivedesign.jsm");
+loader.lazyRequireGetter(this, "ResponsiveUIManager", "devtools/client/responsivedesign/responsivedesign");
 
 /**
  * Open responsive design mode for the given tab.
  */
 var openRDM = Task.async(function* (tab) {
   info("Opening responsive design mode");
   let manager = ResponsiveUIManager;
   let ui = yield manager.openIfNeeded(tab.ownerGlobal, tab);

--- a/devtools/client/responsivedesign/moz.build
+++ b/devtools/client/responsivedesign/moz.build
@@ -3,13 +3,13 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
 
 DevToolsModules(
     'resize-commands.js',
     'responsivedesign-child.js',
     'responsivedesign-old.js',
-    'responsivedesign.jsm',
+    'responsivedesign.js',
 )
 
 with Files('**'):
     BUG_COMPONENT = ('Firefox', 'Developer Tools: Responsive Design Mode')

--- a/devtools/client/responsivedesign/resize-commands.js
+++ b/devtools/client/responsivedesign/resize-commands.js
@@ -1,17 +1,17 @@
 /* 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";
 
 const { Cc, Ci, Cu } = require("chrome");
 
-loader.lazyImporter(this, "ResponsiveUIManager", "resource://devtools/client/responsivedesign/responsivedesign.jsm");
+loader.lazyRequireGetter(this, "ResponsiveUIManager", "devtools/client/responsivedesign/responsivedesign");
 
 const BRAND_SHORT_NAME = Cc["@mozilla.org/intl/stringbundle;1"].
                          getService(Ci.nsIStringBundleService).
                          createBundle("chrome://branding/locale/brand.properties").
                          GetStringFromName("brandShortName");
 
 const Services = require("Services");
 const osString = Services.appinfo.OS;

rename from devtools/client/responsivedesign/responsivedesign.jsm
rename to devtools/client/responsivedesign/responsivedesign.js
--- a/devtools/client/responsivedesign/responsivedesign.jsm
+++ b/devtools/client/responsivedesign/responsivedesign.js
@@ -1,27 +1,22 @@
 /* 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";
 
-const Cu = Components.utils;
-
-const { require } = Cu.import("resource://devtools/shared/Loader.jsm", {});
 const Services = require("Services");
 
 const NEW_RDM_ENABLED = "devtools.responsive.html.enabled";
 
-this.EXPORTED_SYMBOLS = ["ResponsiveUIManager"];
-
 // If the new HTML RDM UI is enabled and e10s is enabled by default (e10s is required for
 // the new HTML RDM UI to function), delegate the ResponsiveUIManager API over to that
 // tool instead.  Performing this delegation here allows us to contain the pref check to a
 // single place.
 if (Services.prefs.getBoolPref(NEW_RDM_ENABLED) &&
     Services.appinfo.browserTabsRemoteAutostart) {
   let { ResponsiveUIManager } = require("devtools/client/responsive.html/manager");
-  this.ResponsiveUIManager = ResponsiveUIManager;
+  module.exports = ResponsiveUIManager;
 } else {
   let { ResponsiveUIManager } = require("devtools/client/responsivedesign/responsivedesign-old");
-  this.ResponsiveUIManager = ResponsiveUIManager;
+  module.exports = ResponsiveUIManager;
 }

--- a/devtools/client/responsivedesign/test/head.js
+++ b/devtools/client/responsivedesign/test/head.js
@@ -22,17 +22,17 @@ registerCleanupFunction(() => {
   Services.prefs.clearUserPref("devtools.responsiveUI.customHeight");
   Services.prefs.clearUserPref("devtools.responsiveUI.customWidth");
   Services.prefs.clearUserPref("devtools.responsiveUI.presets");
   Services.prefs.clearUserPref("devtools.responsiveUI.rotate");
 });
 
 SimpleTest.requestCompleteLog();
 
-const { ResponsiveUIManager } = Cu.import("resource://devtools/client/responsivedesign/responsivedesign.jsm", {});
+loader.lazyRequireGetter(this, "ResponsiveUIManager", "devtools/client/responsivedesign/responsivedesign");
 
 /**
  * Open the Responsive Design Mode
  * @param {Tab} The browser tab to open it into (defaults to the selected tab).
  * @param {method} The method to use to open the RDM (values: menu, keyboard)
  * @return {rdm, manager} Returns the RUI instance and the manager
  */
 var openRDM = Task.async(function* (tab = gBrowser.selectedTab,

--- a/devtools/client/shared/test/browser_telemetry_button_responsive.js
+++ b/devtools/client/shared/test/browser_telemetry_button_responsive.js
@@ -5,17 +5,17 @@
 
 const TEST_URI = "data:text/html;charset=utf-8," +
   "<p>browser_telemetry_button_responsive.js</p>";
 
 // Because we need to gather stats for the period of time that a tool has been
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-const { ResponsiveUIManager } = Cu.import("resource://devtools/client/responsivedesign/responsivedesign.jsm", {});
+loader.lazyRequireGetter(this, "ResponsiveUIManager", "devtools/client/responsivedesign/responsivedesign");
 
 add_task(function* () {
   yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
   let target = TargetFactory.forTab(gBrowser.selectedTab);
   let toolbox = yield gDevTools.showToolbox(target, "inspector");
   info("inspector opened");

--- a/devtools/client/styleeditor/StyleEditorUI.jsm
+++ b/devtools/client/styleeditor/StyleEditorUI.jsm
@@ -5,17 +5,17 @@
 
 "use strict";
 
 this.EXPORTED_SYMBOLS = ["StyleEditorUI"];
 
 const Ci = Components.interfaces;
 const Cu = Components.utils;
 
-const {require} = Cu.import("resource://devtools/shared/Loader.jsm", {});
+const {loader, require} = Cu.import("resource://devtools/shared/Loader.jsm", {});
 const Services = require("Services");
 const {NetUtil} = require("resource://gre/modules/NetUtil.jsm");
 const {OS} = require("resource://gre/modules/osfile.jsm");
 const {Task} = require("devtools/shared/task");
 const EventEmitter = require("devtools/shared/old-event-emitter");
 const {gDevTools} = require("devtools/client/framework/devtools");
 const {
   getString,
@@ -24,20 +24,20 @@ const {
   showFilePicker,
 } = require("resource://devtools/client/styleeditor/StyleEditorUtil.jsm");
 const {SplitView} = require("resource://devtools/client/shared/SplitView.jsm");
 const {StyleSheetEditor} = require("resource://devtools/client/styleeditor/StyleSheetEditor.jsm");
 const {PluralForm} = require("devtools/shared/plural-form");
 const {PrefObserver} = require("devtools/client/shared/prefs");
 const csscoverage = require("devtools/shared/fronts/csscoverage");
 const {console} = require("resource://gre/modules/Console.jsm");
-const {ResponsiveUIManager} =
-  require("resource://devtools/client/responsivedesign/responsivedesign.jsm");
 const {KeyCodes} = require("devtools/client/shared/keycodes");
 
+loader.lazyRequireGetter(this, "ResponsiveUIManager", "devtools/client/responsivedesign/responsivedesign");
+
 const LOAD_ERROR = "error-load";
 const STYLE_EDITOR_TEMPLATE = "stylesheet";
 const SELECTOR_HIGHLIGHTER_TYPE = "SelectorHighlighter";
 const PREF_MEDIA_SIDEBAR = "devtools.styleeditor.showMediaSidebar";
 const PREF_SIDEBAR_WIDTH = "devtools.styleeditor.mediaSidebarWidth";
 const PREF_NAV_WIDTH = "devtools.styleeditor.navSidebarWidth";
 const PREF_ORIG_SOURCES = "devtools.styleeditor.source-maps-enabled";
 

--- a/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar_links.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar_links.js
@@ -11,18 +11,18 @@ const asyncStorage = require("devtools/s
 Services.prefs.setCharPref("devtools.devices.url",
   "http://example.com/browser/devtools/client/responsive.html/test/browser/devices.json");
 
 registerCleanupFunction(() => {
   Services.prefs.clearUserPref("devtools.devices.url");
   asyncStorage.removeItem("devtools.devices.url_cache");
 });
 
-const mgr = "resource://devtools/client/responsivedesign/responsivedesign.jsm";
-const {ResponsiveUIManager} = Cu.import(mgr, {});
+loader.lazyRequireGetter(this, "ResponsiveUIManager", "devtools/client/responsivedesign/responsivedesign");
+
 const TESTCASE_URI = TEST_BASE_HTTPS + "media-rules.html";
 const responsiveModeToggleClass = ".media-responsive-mode-toggle";
 
 add_task(function* () {
   let {ui} = yield openStyleEditorForURL(TESTCASE_URI);
 
   let editor = ui.editors[1];
   yield openEditor(editor);

--- a/tools/lint/eslint/modules.json
+++ b/tools/lint/eslint/modules.json
@@ -180,17 +180,16 @@
   "record.js": ["WBORecord", "RecordManager", "CryptoWrapper", "CollectionKeyManager", "Collection"],
   "recursive_importA.jsm": ["foo", "bar"],
   "recursive_importB.jsm": ["baz", "qux"],
   "reflect.jsm": ["Reflect"],
   "RemoteFinder.jsm": ["RemoteFinder", "RemoteFinderListener"],
   "RemotePageManager.jsm": ["RemotePages", "RemotePageManager", "PageListener"],
   "RemoteWebProgress.jsm": ["RemoteWebProgressManager"],
   "resource.js": ["AsyncResource", "Resource"],
-  "responsivedesign.jsm": ["ResponsiveUIManager"],
   "rest.js": ["RESTRequest", "RESTResponse", "TokenAuthenticatedRESTRequest", "SyncStorageRequest"],
   "rotaryengine.js": ["RotaryEngine", "RotaryRecord", "RotaryStore", "RotaryTracker"],
   "require.js": ["require"],
   "RTCStatsReport.jsm": ["convertToRTCStatsReport"],
   "scratchpad-manager.jsm": ["ScratchpadManager"],
   "server.js": ["server"],
   "service.js": ["Service"],
   "SharedPromptUtils.jsm": ["PromptUtils", "EnableDelayHelper"],