rename from browser/modules/LightWeightThemeWebInstallListener.jsm
rename to browser/actors/LightWeightThemeInstallChild.jsm
--- a/browser/modules/LightWeightThemeWebInstallListener.jsm
+++ b/browser/actors/LightWeightThemeInstallChild.jsm
@@ -1,19 +1,19 @@
 /* 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/. */
 
-var EXPORTED_SYMBOLS = ["LightWeightThemeWebInstallListener"];
+var EXPORTED_SYMBOLS = ["LightWeightThemeInstallChild"];
+
+ChromeUtils.import("resource://gre/modules/ActorChild.jsm");
 
-var LightWeightThemeWebInstallListener = {
-  _previewWindow: null,
-
+class LightWeightThemeInstallChild extends ActorChild {
   handleEvent(event) {
-    let mm = getMessageManagerForContent(event.target.ownerGlobal);
+    let {mm} = this;
     switch (event.type) {
       case "InstallBrowserTheme": {
         mm.sendAsyncMessage("LightWeightThemeWebInstaller:Install", {
           baseURI: event.target.baseURI,
           principal: event.target.nodePrincipal,
           themeData: event.target.getAttribute("data-browsertheme"),
         });
         break;
@@ -37,19 +37,15 @@ var LightWeightThemeWebInstallListener =
         if (this._previewWindow) {
           mm.sendAsyncMessage("LightWeightThemeWebInstaller:ResetPreview",
                            {principal: event.target.nodePrincipal});
           this._resetPreviewWindow();
         }
         break;
       }
     }
-  },
+  }
 
   _resetPreviewWindow() {
     this._previewWindow.removeEventListener("pagehide", this, true);
     this._previewWindow = null;
   }
-};
-
-function getMessageManagerForContent(content) {
-  return content.docShell.messageManager;
 }

--- a/browser/actors/moz.build
+++ b/browser/actors/moz.build
@@ -1,21 +1,25 @@
 # -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
 # vim: set filetype=python:
 # 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/.
 
+with Files("LightWeightThemeInstallChild.jsm"):
+    BUG_COMPONENT = ("Firefox", "Theme")
+
 with Files("PageInfoChild.jsm"):
     BUG_COMPONENT = ("Firefox", "Page Info Window")
 
 with Files("PageStyleChild.jsm"):
     BUG_COMPONENT = ("Firefox", "Menus")
 
 FINAL_TARGET_FILES.actors += [
     'AboutReaderChild.jsm',
     'BrowserTabChild.jsm',
     'ClickHandlerChild.jsm',
     'ContentSearchChild.jsm',
     'ContextMenuChild.jsm',
+    'LightWeightThemeInstallChild.jsm',
     'PageInfoChild.jsm',
     'PageStyleChild.jsm',
 ]

--- a/browser/base/content/content.js
+++ b/browser/base/content/content.js
@@ -39,19 +39,16 @@ XPCOMUtils.defineLazyGetter(this, "Login
 
 XPCOMUtils.defineLazyProxy(this, "formSubmitObserver", () => {
   return new FormSubmitObserver(content, this);
 }, {
   // stub QI
   QueryInterface: ChromeUtils.generateQI([Ci.nsIFormSubmitObserver, Ci.nsISupportsWeakReference])
 });
 
-XPCOMUtils.defineLazyProxy(this, "LightWeightThemeWebInstallListener",
-                           "resource:///modules/LightWeightThemeWebInstallListener.jsm");
-
 Services.obs.addObserver(formSubmitObserver, "invalidformsubmit", true);
 
 // NOTE: Much of this logic is duplicated in BrowserCLH.js for Android.
 addMessageListener("RemoteLogins:fillForm", function(message) {
   // intercept if ContextMenu.jsm had sent a plain object for remote targets
   message.objects.inputElement = ContextMenuChild.getTarget(global, message, "inputElement");
   LoginManagerContent.receiveMessage(message, content);
 });
@@ -261,20 +258,16 @@ var PageMetadataMessenger = {
         sendAsyncMessage("PageMetadata:MicroformatsResult", result);
         break;
       }
     }
   }
 };
 PageMetadataMessenger.init();
 
-addEventListener("InstallBrowserTheme", LightWeightThemeWebInstallListener, false, true);
-addEventListener("PreviewBrowserTheme", LightWeightThemeWebInstallListener, false, true);
-addEventListener("ResetBrowserThemePreview", LightWeightThemeWebInstallListener, false, true);
-
 let OfflineApps = {
   _docId: 0,
   _docIdMap: new Map(),
 
   _docManifestSet: new Set(),
 
   _observerAdded: false,
   registerWindow(aWindow) {

--- a/browser/components/nsBrowserGlue.js
+++ b/browser/components/nsBrowserGlue.js
@@ -82,16 +82,27 @@ let ACTORS = {
         "ContentSearchClient": {capture: true, wantUntrusted: true},
       },
       messages: [
         "ContentSearch",
       ]
     },
   },
 
+  LightWeightThemeInstall: {
+    child: {
+      module: "resource:///actors/LightWeightThemeInstallChild.jsm",
+      events: {
+        "InstallBrowserTheme": {wantUntrusted: true},
+        "PreviewBrowserTheme": {wantUntrusted: true},
+        "ResetBrowserThemePreview": {wantUntrusted: true},
+      },
+    },
+  },
+
   PageInfo: {
     child: {
       module: "resource:///actors/PageInfoChild.jsm",
       messages: ["PageInfo:getData"],
     },
   },
 
   PageStyle: {

--- a/browser/modules/moz.build
+++ b/browser/modules/moz.build
@@ -62,19 +62,16 @@ with Files("ExtensionsUI.jsm"):
     BUG_COMPONENT = ("WebExtensions", "General")
 
 with Files("LaterRun.jsm"):
     BUG_COMPONENT = ("Firefox", "Tours")
 
 with Files("LightweightThemeChildHelper.jsm"):
     BUG_COMPONENT = ("WebExtensions", "Themes")
 
-with Files("LightWeightThemeWebInstallListener.jsm"):
-    BUG_COMPONENT = ("Firefox", "Theme")
-
 with Files("OpenInTabsUtils.jsm"):
     BUG_COMPONENT = ("Firefox", "Tabbed Browser")
 
 with Files("PermissionUI.jsm"):
    BUG_COMPONENT = ("Firefox", "Site Identity and Permission Panels")
 
 with Files("PluginContent.jsm"):
     BUG_COMPONENT = ("Core", "Plug-ins")
@@ -141,17 +138,16 @@ EXTRA_JS_MODULES += [
     'ContentWebRTC.jsm',
     'ExtensionsUI.jsm',
     'Feeds.jsm',
     'FormSubmitObserver.jsm',
     'FormValidationHandler.jsm',
     'HomePage.jsm',
     'LaterRun.jsm',
     'LightweightThemeChildHelper.jsm',
-    'LightWeightThemeWebInstallListener.jsm',
     'NetErrorContent.jsm',
     'OpenInTabsUtils.jsm',
     'PageActions.jsm',
     'PermissionUI.jsm',
     'PingCentre.jsm',
     'PluginContent.jsm',
     'ProcessHangMonitor.jsm',
     'ReaderParent.jsm',