diff --git a/toolkit/components/remotepagemanager/RemotePageManagerChild.jsm b/toolkit/components/remotepagemanager/RemotePageManagerChild.jsm
index 4b77e77eb950..ea798a4b6301 100644
--- a/toolkit/components/remotepagemanager/RemotePageManagerChild.jsm
+++ b/toolkit/components/remotepagemanager/RemotePageManagerChild.jsm
@@ -13,10 +13,10 @@ const { MessagePort } = ChromeUtils.import(
 
 // The content side of a message port
 class ChildMessagePort extends MessagePort {
-  constructor(actor, window) {
+  constructor(window) {
     let portID =
       Services.appinfo.processID + ":" + ChildMessagePort.nextPortID++;
-    super(actor, portID);
+    super(window.docShell.messageManager, portID);
 
     this.window = window;
 
diff --git a/toolkit/content/process-content.js b/toolkit/content/process-content.js
index 458f5be38045..3f4ec0d3ba90 100644
--- a/toolkit/content/process-content.js
+++ b/toolkit/content/process-content.js
@@ -1,7 +1,6 @@
 /* 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";
 
 // Creates a new PageListener for this process. This will listen for page loads
@@ -9,37 +8,18 @@
 // a dedicated message port and notify the parent process.
 const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
 
-const gInContentProcess =
-  Services.appinfo.processType == Ci.nsIXULRuntime.PROCESS_TYPE_CONTENT;
-
-Services.cpmm.addMessageListener("gmp-plugin-crash", msg => {
-  let gmpservice = Cc["@mozilla.org/gecko-media-plugin-service;1"].getService(
-    Ci.mozIGeckoMediaPluginService
-  );
-
-  gmpservice.RunPluginCrashCallbacks(msg.data.pluginID, msg.data.pluginName);
+Services.cpmm.addMessageListener("gmp-plugin-crash", ({ data }) => {
+  Cc["@mozilla.org/gecko-media-plugin-service;1"]
+    .getService(Ci.mozIGeckoMediaPluginService)
+    .RunPluginCrashCallbacks(data.pluginID, data.pluginName);
 });
 
-let TOPICS = [
-  "chrome-document-global-created",
-  "content-document-global-created",
-];
-
-if (gInContentProcess) {
-  TOPICS.push("inner-window-destroyed");
-  TOPICS.push("xpcom-shutdown");
-}
-
 let ProcessObserver = {
   init() {
-    for (let topic of TOPICS) {
-      Services.obs.addObserver(this, topic);
-    }
-  },
-
-  uninit() {
-    for (let topic of TOPICS) {
-      Services.obs.removeObserver(this, topic);
+    Services.obs.addObserver(this, "chrome-document-global-created");
+    Services.obs.addObserver(this, "content-document-global-created");
+    if (Services.appinfo.processType == Ci.nsIXULRuntime.PROCESS_TYPE_CONTENT) {
+      Services.obs.addObserver(this, "inner-window-destroyed");
     }
   },
 
@@ -49,44 +29,33 @@ let ProcessObserver = {
       case "content-document-global-created": {
         // Strip the hash from the URL, because it's not part of the origin.
         let window = subject;
-        let url = window.document.documentURI.replace(/[\#|\?].*$/, "");
+        let url = window.document.documentURI.replace(/[#?].*$/, "");
 
         let registeredURLs = Services.cpmm.sharedData.get(
           "RemotePageManager:urls"
         );
-
-        if (!registeredURLs || !registeredURLs.has(url)) {
-          return;
+        if (registeredURLs && registeredURLs.has(url)) {
+          let { ChildMessagePort } = ChromeUtils.import(
+            "resource://gre/modules/remotepagemanager/RemotePageManagerChild.jsm"
+          );
+          // Set up the child side of the message port
+          new ChildMessagePort(window);
         }
-
-        // Get the frame message manager for this window so we can associate this
-        // page with a browser element
-        let messageManager = window.docShell.messageManager;
-
-        let { ChildMessagePort } = ChromeUtils.import(
-          "resource://gre/modules/remotepagemanager/RemotePageManagerChild.jsm"
-        );
-        // Set up the child side of the message port
-        new ChildMessagePort(messageManager, window);
         break;
       }
-      case "inner-window-destroyed": {
+      case "inner-window-destroyed":
         // Forward inner-window-destroyed notifications with the
         // inner window ID, so that code in the parent that should
         // do something when content windows go away can do it
-        let innerWindowID = subject.QueryInterface(Ci.nsISupportsPRUint64).data;
         Services.cpmm.sendAsyncMessage(
           "Toolkit:inner-window-destroyed",
-          innerWindowID
+          subject.nsISupportsPRUint64.data
         );
         break;
-      }
-      case "xpcom-shutdown": {
-        this.uninit();
-        break;
-      }
     }
   },
 };
 
 ProcessObserver.init();
+// Drop the reference so it can be GCed.
+ProcessObserver.init = null;