--- a/browser/components/preferences/connection.js
+++ b/browser/components/preferences/connection.js
@@ -1,16 +1,15 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 4 -*- */
 /* 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/. */
 
 /* import-globals-from ../../base/content/utilityOverlay.js */
 /* import-globals-from ../../../toolkit/content/preferencesBindings.js */
-/* import-globals-from in-content/extensionControlled.js */
 
 Preferences.addAll([
   { id: "network.proxy.type", type: "int" },
   { id: "network.proxy.http", type: "string" },
   { id: "network.proxy.http_port", type: "int" },
   { id: "network.proxy.ftp", type: "string" },
   { id: "network.proxy.ftp_port", type: "int" },
   { id: "network.proxy.ssl", type: "string" },
@@ -32,24 +31,16 @@ Preferences.addAll([
   { id: "network.proxy.backup.socks_port", type: "int" },
 ]);
 
 window.addEventListener("DOMContentLoaded", () => {
   Preferences.get("network.proxy.type").on("change",
     gConnectionsDialog.proxyTypeChanged.bind(gConnectionsDialog));
   Preferences.get("network.proxy.socks_version").on("change",
     gConnectionsDialog.updateDNSPref.bind(gConnectionsDialog));
-
-  document
-    .getElementById("disableProxyExtension")
-    .addEventListener(
-      "command", makeDisableControllingExtension(
-        PREF_SETTING_TYPE, PROXY_KEY).bind(gConnectionsDialog));
-  gConnectionsDialog.updateProxySettingsUI();
-  initializeProxyUI(gConnectionsDialog);
 }, { once: true, capture: true });
 
 var gConnectionsDialog = {
   beforeAccept() {
     var proxyTypePref = Preferences.get("network.proxy.type");
     if (proxyTypePref.value == 2) {
       this.doAutoconfigURLFixup();
       return true;
@@ -231,45 +222,10 @@ var gConnectionsDialog = {
     return undefined;
   },
 
   readHTTPProxyPort() {
     var shareProxiesPref = Preferences.get("network.proxy.share_proxy_settings");
     if (shareProxiesPref.value)
       this.updateProtocolPrefs();
     return undefined;
-  },
-
-  getProxyControls() {
-    let controlGroup = document.getElementById("networkProxyType");
-    return [
-      ...controlGroup.querySelectorAll(":scope > radio"),
-      ...controlGroup.querySelectorAll("label"),
-      ...controlGroup.querySelectorAll("textbox"),
-      ...controlGroup.querySelectorAll("checkbox"),
-      ...document.querySelectorAll("#networkProxySOCKSVersion > radio"),
-      ...document.querySelectorAll("#ConnectionsDialogPane > checkbox"),
-    ];
-  },
-
-  // Update the UI to show/hide the extension controlled message for
-  // proxy settings.
-  async updateProxySettingsUI() {
-    let isLocked = API_PROXY_PREFS.some(
-      pref => Services.prefs.prefIsLocked(pref));
-
-    function setInputsDisabledState(isControlled) {
-      let disabled = isLocked || isControlled;
-      for (let element of gConnectionsDialog.getProxyControls()) {
-        element.disabled = disabled;
-      }
-    }
-
-    if (isLocked) {
-      // An extension can't control this setting if any pref is locked.
-      hideControllingExtension(PROXY_KEY);
-      setInputsDisabledState(false);
-    } else {
-      handleControllingExtension(PREF_SETTING_TYPE, PROXY_KEY)
-        .then(setInputsDisabledState);
-    }
   }
 };

--- a/browser/components/preferences/connection.xul
+++ b/browser/components/preferences/connection.xul
@@ -4,18 +4,16 @@
    - 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/. -->
 
 <!DOCTYPE dialog [
   <!ENTITY % preferencesDTD SYSTEM "chrome://global/locale/preferences.dtd">
   %preferencesDTD;
   <!ENTITY % connectionDTD SYSTEM "chrome://browser/locale/preferences/connection.dtd">
   %connectionDTD;
-  <!ENTITY % mainDTD SYSTEM "chrome://browser/locale/preferences/main.dtd">
-  %mainDTD;
 ]>
 
 <?xml-stylesheet href="chrome://global/skin/"?>
 <?xml-stylesheet href="chrome://browser/skin/preferences/preferences.css"?>
 
 <dialog id="ConnectionsDialog" type="child" class="prefwindow"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         title="&connectionsDialog.title;"
@@ -32,37 +30,28 @@
 #ifdef XP_MACOSX
         style="width: &window.macWidth2; !important;">
 #else
         style="width: &window.width2; !important;">
 #endif
 
   <script type="application/javascript" src="chrome://browser/content/utilityOverlay.js"/>
   <script type="application/javascript" src="chrome://global/content/preferencesBindings.js"/>
-  <script type="application/javascript" src="chrome://browser/content/preferences/in-content/extensionControlled.js"/>
 
   <keyset>
     <key key="&windowClose.key;" modifiers="accel" oncommand="Preferences.close(event)"/>
   </keyset>
 
   <vbox id="ConnectionsDialogPane" class="prefpane largeDialogContainer">
 
-    <stringbundle id="bundlePreferences" src="chrome://browser/locale/preferences/preferences.properties"/>
-    <stringbundle id="bundleBrand" src="chrome://branding/locale/brand.properties"/>
+    <stringbundle id="preferencesBundle" src="chrome://browser/locale/preferences/preferences.properties"/>
     <script type="application/javascript" src="chrome://browser/content/preferences/connection.js"/>
 
-    <hbox id="proxyExtensionContent" align="top" hidden="true">
-      <description control="disableProxyExtension" flex="1" />
-      <button id="disableProxyExtension"
-              class="extension-controlled-button accessory-button"
-              label="&disableExtension.label;" />
-    </hbox>
-
     <groupbox>
-      <caption><label>&proxyTitle.label2;</label></caption>
+      <caption><label>&proxyTitle.label;</label></caption>
 
       <radiogroup id="networkProxyType" preference="network.proxy.type"
                   onsyncfrompreference="return gConnectionsDialog.readProxyType();">
         <radio value="0" label="&noProxyTypeRadio.label;" accesskey="&noProxyTypeRadio.accesskey;"/>
         <radio value="4" label="&WPADTypeRadio.label;" accesskey="&WPADTypeRadio.accesskey;"/>
         <radio value="5" label="&systemTypeRadio.label;" accesskey="&systemTypeRadio.accesskey;" id="systemPref" hidden="true"/>
         <radio value="1" label="&manualTypeRadio2.label;" accesskey="&manualTypeRadio2.accesskey;"/>
         <grid class="indent" flex="1">

deleted file mode 100644
--- a/browser/components/preferences/in-content/extensionControlled.js
+++ /dev/null
@@ -1,221 +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/. */
-
-/* import-globals-from preferences.js */
-
-"use strict";
-
-ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
-
-ChromeUtils.defineModuleGetter(this, "AddonManager",
-                                  "resource://gre/modules/AddonManager.jsm");
-ChromeUtils.defineModuleGetter(this, "BrowserUtils",
-                                  "resource://gre/modules/BrowserUtils.jsm");
-ChromeUtils.defineModuleGetter(this, "DeferredTask",
-                                  "resource://gre/modules/DeferredTask.jsm");
-ChromeUtils.defineModuleGetter(this, "ExtensionSettingsStore",
-                                  "resource://gre/modules/ExtensionSettingsStore.jsm");
-
-XPCOMUtils.defineLazyPreferenceGetter(this, "trackingprotectionUiEnabled",
-                                      "privacy.trackingprotection.ui.enabled");
-
-const PREF_SETTING_TYPE = "prefs";
-const PROXY_KEY = "proxyConfig";
-const API_PROXY_PREFS = [
-  "network.proxy.type",
-  "network.proxy.http",
-  "network.proxy.http_port",
-  "network.proxy.share_proxy_settings",
-  "network.proxy.ftp",
-  "network.proxy.ftp_port",
-  "network.proxy.ssl",
-  "network.proxy.ssl_port",
-  "network.proxy.socks",
-  "network.proxy.socks_port",
-  "network.proxy.socks_version",
-  "network.proxy.socks_remote_dns",
-  "network.proxy.no_proxies_on",
-  "network.proxy.autoconfig_url",
-  "signon.autologin.proxy",
-];
-
-let extensionControlledContentIds = {
-  "privacy.containers": "browserContainersExtensionContent",
-  "homepage_override": "browserHomePageExtensionContent",
-  "newTabURL": "browserNewTabExtensionContent",
-  "defaultSearch": "browserDefaultSearchExtensionContent",
-  "proxyConfig": "proxyExtensionContent",
-  get "websites.trackingProtectionMode"() {
-    return {
-      button: "trackingProtectionExtensionContentButton",
-      section:
-        trackingprotectionUiEnabled ?
-          "trackingProtectionExtensionContentLabel" :
-          "trackingProtectionPBMExtensionContentLabel",
-    };
-  }
-};
-
-function getExtensionControlledArgs(settingName) {
-  switch (settingName) {
-    case "proxyConfig":
-      return [document.getElementById("bundleBrand").getString("brandShortName")];
-    default:
-      return [];
-  }
-}
-
-let extensionControlledIds = {};
-
-/**
-  * Check if a pref is being managed by an extension.
-  */
-async function getControllingExtensionInfo(type, settingName) {
-  await ExtensionSettingsStore.initialize();
-  return ExtensionSettingsStore.getSetting(type, settingName);
-}
-
-function getControllingExtensionEls(settingName) {
-  let idInfo = extensionControlledContentIds[settingName];
-  let section = document.getElementById(idInfo.section || idInfo);
-  let button = idInfo.button ?
-    document.getElementById(idInfo.button) :
-    section.querySelector("button");
-  return {
-    section,
-    button,
-    description: section.querySelector("description"),
-  };
-}
-
-async function getControllingExtension(type, settingName) {
-  let info = await getControllingExtensionInfo(type, settingName);
-  let addon = info && info.id
-    && await AddonManager.getAddonByID(info.id);
-  return addon;
-}
-
-async function handleControllingExtension(type, settingName) {
-  let addon = await getControllingExtension(type, settingName);
-
-  // Sometimes the ExtensionSettingsStore gets in a bad state where it thinks
-  // an extension is controlling a setting but the extension has been uninstalled
-  // outside of the regular lifecycle. If the extension isn't currently installed
-  // then we should treat the setting as not being controlled.
-  // See https://bugzilla.mozilla.org/show_bug.cgi?id=1411046 for an example.
-  if (addon) {
-    extensionControlledIds[settingName] = addon.id;
-    showControllingExtension(settingName, addon);
-  } else {
-    let elements = getControllingExtensionEls(settingName);
-    if (extensionControlledIds[settingName]
-        && !document.hidden
-        && elements.button) {
-      showEnableExtensionMessage(settingName);
-    } else {
-      hideControllingExtension(settingName);
-    }
-    delete extensionControlledIds[settingName];
-  }
-
-  return !!addon;
-}
-
-function getControllingExtensionFragment(settingName, addon, ...extraArgs) {
-  let msg = document.getElementById("bundlePreferences")
-                    .getString(`extensionControlled.${settingName}`);
-  let image = document.createElement("image");
-  const defaultIcon = "chrome://mozapps/skin/extensions/extensionGeneric.svg";
-  image.setAttribute("src", addon.iconURL || defaultIcon);
-  image.classList.add("extension-controlled-icon");
-  let addonBit = document.createDocumentFragment();
-  addonBit.appendChild(image);
-  addonBit.appendChild(document.createTextNode(" " + addon.name));
-  return BrowserUtils.getLocalizedFragment(document, msg, addonBit, ...extraArgs);
-}
-
-async function showControllingExtension(settingName, addon) {
-  // Tell the user what extension is controlling the setting.
-  let elements = getControllingExtensionEls(settingName);
-  let extraArgs = getExtensionControlledArgs(settingName);
-
-  elements.section.classList.remove("extension-controlled-disabled");
-  let description = elements.description;
-
-  // Remove the old content from the description.
-  while (description.firstChild) {
-    description.firstChild.remove();
-  }
-
-  let fragment = getControllingExtensionFragment(
-    settingName, addon, ...extraArgs);
-  description.appendChild(fragment);
-
-  if (elements.button) {
-    elements.button.hidden = false;
-  }
-
-  // Show the controlling extension row and hide the old label.
-  elements.section.hidden = false;
-}
-
-function hideControllingExtension(settingName) {
-  let elements = getControllingExtensionEls(settingName);
-  elements.section.hidden = true;
-  if (elements.button) {
-    elements.button.hidden = true;
-  }
-}
-
-function showEnableExtensionMessage(settingName) {
-  let elements = getControllingExtensionEls(settingName);
-
-  elements.button.hidden = true;
-  elements.section.classList.add("extension-controlled-disabled");
-  let icon = url => {
-    let img = document.createElement("image");
-    img.src = url;
-    img.className = "extension-controlled-icon";
-    return img;
-  };
-  let addonIcon = icon("chrome://mozapps/skin/extensions/extensionGeneric-16.svg");
-  let toolbarIcon = icon("chrome://browser/skin/menu.svg");
-  let message = document.getElementById("bundlePreferences")
-                        .getString("extensionControlled.enable");
-  let frag = BrowserUtils.getLocalizedFragment(document, message, addonIcon, toolbarIcon);
-  elements.description.innerHTML = "";
-  elements.description.appendChild(frag);
-  let dismissButton = document.createElement("image");
-  dismissButton.setAttribute("class", "extension-controlled-icon close-icon");
-  dismissButton.addEventListener("click", function dismissHandler() {
-    hideControllingExtension(settingName);
-    dismissButton.removeEventListener("click", dismissHandler);
-  });
-  elements.description.appendChild(dismissButton);
-}
-
-function makeDisableControllingExtension(type, settingName) {
-  return async function disableExtension() {
-    let {id} = await getControllingExtensionInfo(type, settingName);
-    let addon = await AddonManager.getAddonByID(id);
-    addon.userDisabled = true;
-  };
-}
-
-function initializeProxyUI(container) {
-  let deferredUpdate = new DeferredTask(() => {
-    container.updateProxySettingsUI();
-  }, 10);
-  let proxyObserver = {
-    observe: (subject, topic, data) => {
-      if (API_PROXY_PREFS.includes(data)) {
-        deferredUpdate.arm();
-      }
-    },
-  };
-  Services.prefs.addObserver("", proxyObserver);
-  window.addEventListener("unload", () => {
-    Services.prefs.removeObserver("", proxyObserver);
-  });
-}

--- a/browser/components/preferences/in-content/findInPage.js
+++ b/browser/components/preferences/in-content/findInPage.js
@@ -1,13 +1,12 @@
 /* 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/. */
 
-/* import-globals-from extensionControlled.js */
 /* import-globals-from preferences.js */
 
 var gSearchResultsPane = {
   listSearchTooltips: new Set(),
   listSearchMenuitemIndicators: new Set(),
   searchInput: null,
   inited: false,
 

--- a/browser/components/preferences/in-content/jar.mn
+++ b/browser/components/preferences/in-content/jar.mn
@@ -1,15 +1,14 @@
 # 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/.
 
 browser.jar:
    content/browser/preferences/in-content/preferences.js
-   content/browser/preferences/in-content/extensionControlled.js
 *  content/browser/preferences/in-content/preferences.xul
    content/browser/preferences/in-content/subdialogs.js
 
    content/browser/preferences/in-content/main.js
    content/browser/preferences/in-content/search.js
    content/browser/preferences/in-content/privacy.js
    content/browser/preferences/in-content/containers.js
    content/browser/preferences/in-content/sync.js

--- a/browser/components/preferences/in-content/main.js
+++ b/browser/components/preferences/in-content/main.js
@@ -1,13 +1,12 @@
 /* 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/. */
 
-/* import-globals-from extensionControlled.js */
 /* import-globals-from preferences.js */
 /* import-globals-from ../../../../toolkit/mozapps/preferences/fontbuilder.js */
 /* import-globals-from ../../../base/content/aboutDialog-appUpdater.js */
 
 ChromeUtils.import("resource://gre/modules/Services.jsm");
 ChromeUtils.import("resource://gre/modules/Downloads.jsm");
 ChromeUtils.import("resource://gre/modules/FileUtils.jsm");
 ChromeUtils.import("resource:///modules/ShellService.jsm");
@@ -363,23 +362,16 @@ var gMainPane = {
           handleControllingExtension(URL_OVERRIDES_TYPE, NEW_TAB_KEY);
       },
     };
     Services.obs.addObserver(newTabObserver, "newtab-url-changed");
     window.addEventListener("unload", () => {
       Services.obs.removeObserver(newTabObserver, "newtab-url-changed");
     });
 
-    let connectionSettingsLink = document.getElementById("connectionSettingsLearnMore");
-    let connectionSettingsUrl = Services.urlFormatter.formatURLPref("app.support.baseURL") +
-                                "prefs-connection-settings";
-    connectionSettingsLink.setAttribute("href", connectionSettingsUrl);
-    this.updateProxySettingsUI();
-    initializeProxyUI(gMainPane);
-
     if (AppConstants.platform == "win") {
       // Functionality for "Show tabs in taskbar" on Windows 7 and up.
       try {
         let ver = parseFloat(Services.sysinfo.getProperty("version"));
         let showTabsInTaskbar = document.getElementById("showTabsInTaskbar");
         showTabsInTaskbar.hidden = ver < 6.1;
       } catch (ex) { }
     }
@@ -1093,38 +1085,17 @@ var gMainPane = {
     gSubDialog.open("chrome://browser/content/preferences/colors.xul", "resizable=no");
   },
 
   // NETWORK
   /**
    * Displays a dialog in which proxy settings may be changed.
    */
   showConnections() {
-    gSubDialog.open("chrome://browser/content/preferences/connection.xul",
-                    null, null, this.updateProxySettingsUI.bind(this));
-  },
-
-  // Update the UI to show the proper description depending on whether an
-  // extension is in control or not.
-  async updateProxySettingsUI() {
-    let controllingExtension = await getControllingExtension(PREF_SETTING_TYPE, PROXY_KEY);
-    let fragment = controllingExtension ?
-      getControllingExtensionFragment(PROXY_KEY, controllingExtension, this._brandShortName) :
-      BrowserUtils.getLocalizedFragment(
-        document,
-        this._prefsBundle.getString("connectionDesc.label"),
-        this._brandShortName);
-    let description = document.getElementById("connectionSettingsDescription");
-
-    // Remove the old content from the description.
-    while (description.firstChild) {
-      description.firstChild.remove();
-    }
-
-    description.appendChild(fragment);
+    gSubDialog.open("chrome://browser/content/preferences/connection.xul");
   },
 
   checkBrowserContainers(event) {
     let checkbox = document.getElementById("browserContainersCheckbox");
     if (checkbox.checked) {
       Services.prefs.setBoolPref("privacy.userContext.enabled", true);
       return;
     }

--- a/browser/components/preferences/in-content/main.xul
+++ b/browser/components/preferences/in-content/main.xul
@@ -744,25 +744,17 @@
   <label class="header-name" flex="1">&networkProxy.label;</label>
 </hbox>
 
 <!-- Network Proxy-->
 <groupbox id="connectionGroup" data-category="paneGeneral" hidden="true">
   <caption class="search-header" hidden="true"><label>&networkProxy.label;</label></caption>
 
   <hbox align="center">
-    <hbox align="center" flex="1">
-      <description id="connectionSettingsDescription" control="connectionSettings"></description>
-      <spacer width="5"/>
-      <label id="connectionSettingsLearnMore" class="learnMore text-link">
-        &connectionSettingsLearnMore.label;
-      </label>
-      <separator orient="vertical"/>
-    </hbox>
-
+    <description flex="1" control="connectionSettings">&connectionDesc.label;</description>
     <!-- Please don't remove the wrapping hbox/vbox/box for these elements. It's used to properly compute the search tooltip position. -->
     <hbox>
       <button id="connectionSettings"
               class="accessory-button"
               icon="network"
               label="&connectionSettings.label;"
               accesskey="&connectionSettings.accesskey;"
               searchkeywords="&connectionsDialog.title;

--- a/browser/components/preferences/in-content/preferences.js
+++ b/browser/components/preferences/in-content/preferences.js
@@ -15,22 +15,32 @@
 
 "use strict";
 
 var Cc = Components.classes;
 var Ci = Components.interfaces;
 var Cu = Components.utils;
 var Cr = Components.results;
 
+ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
 ChromeUtils.import("resource://gre/modules/Services.jsm");
 ChromeUtils.import("resource://gre/modules/AppConstants.jsm");
 
+ChromeUtils.defineModuleGetter(this, "AddonManager",
+                               "resource://gre/modules/AddonManager.jsm");
+ChromeUtils.defineModuleGetter(this, "BrowserUtils",
+                               "resource://gre/modules/BrowserUtils.jsm");
+ChromeUtils.defineModuleGetter(this, "ExtensionSettingsStore",
+                               "resource://gre/modules/ExtensionSettingsStore.jsm");
 ChromeUtils.defineModuleGetter(this, "formAutofillParent",
                                "resource://formautofill/FormAutofillParent.jsm");
 
+XPCOMUtils.defineLazyPreferenceGetter(this, "trackingprotectionUiEnabled",
+                                      "privacy.trackingprotection.ui.enabled");
+
 var gLastHash = "";
 
 var gCategoryInits = new Map();
 function init_category_if_required(category) {
   let categoryInfo = gCategoryInits.get(category);
   if (!categoryInfo) {
     throw "Unknown in-content prefs category! Can't init " + category;
   }
@@ -407,8 +417,153 @@ function confirmRestartPrompt(aRestartTo
 function appendSearchKeywords(aId, keywords) {
   let element = document.getElementById(aId);
   let searchKeywords = element.getAttribute("searchkeywords");
   if (searchKeywords) {
     keywords.push(searchKeywords);
   }
   element.setAttribute("searchkeywords", keywords.join(" "));
 }
+
+const PREF_SETTING_TYPE = "prefs";
+
+let extensionControlledContentIds = {
+  "privacy.containers": "browserContainersExtensionContent",
+  "homepage_override": "browserHomePageExtensionContent",
+  "newTabURL": "browserNewTabExtensionContent",
+  "defaultSearch": "browserDefaultSearchExtensionContent",
+  get "websites.trackingProtectionMode"() {
+    return {
+      button: "trackingProtectionExtensionContentButton",
+      section:
+        trackingprotectionUiEnabled ?
+          "trackingProtectionExtensionContentLabel" :
+          "trackingProtectionPBMExtensionContentLabel",
+    };
+  }
+};
+
+let extensionControlledIds = {};
+
+/**
+  * Check if a pref is being managed by an extension.
+  */
+async function getControllingExtensionInfo(type, settingName) {
+  await ExtensionSettingsStore.initialize();
+  return ExtensionSettingsStore.getSetting(type, settingName);
+}
+
+function getControllingExtensionEls(settingName) {
+  let idInfo = extensionControlledContentIds[settingName];
+  let section = document.getElementById(idInfo.section || idInfo);
+  let button = idInfo.button ?
+    document.getElementById(idInfo.button) :
+    section.querySelector("button");
+  return {
+    section,
+    button,
+    description: section.querySelector("description"),
+  };
+}
+
+async function handleControllingExtension(type, settingName) {
+  let info = await getControllingExtensionInfo(type, settingName);
+  let addon = info && info.id
+    && await AddonManager.getAddonByID(info.id);
+
+  // Sometimes the ExtensionSettingsStore gets in a bad state where it thinks
+  // an extension is controlling a setting but the extension has been uninstalled
+  // outside of the regular lifecycle. If the extension isn't currently installed
+  // then we should treat the setting as not being controlled.
+  // See https://bugzilla.mozilla.org/show_bug.cgi?id=1411046 for an example.
+  if (addon) {
+    extensionControlledIds[settingName] = info.id;
+    showControllingExtension(settingName, addon);
+  } else {
+    let elements = getControllingExtensionEls(settingName);
+    if (extensionControlledIds[settingName]
+        && !document.hidden
+        && elements.button) {
+      showEnableExtensionMessage(settingName);
+    } else {
+      hideControllingExtension(settingName);
+    }
+    delete extensionControlledIds[settingName];
+  }
+
+  return !!addon;
+}
+
+async function showControllingExtension(settingName, addon) {
+  // Tell the user what extension is controlling the setting.
+  let elements = getControllingExtensionEls(settingName);
+
+  elements.section.classList.remove("extension-controlled-disabled");
+  let description = elements.description;
+
+  // Remove the old content from the description.
+  while (description.firstChild) {
+    description.firstChild.remove();
+  }
+
+  // Populate the description.
+  let msg = document.getElementById("bundlePreferences")
+                    .getString(`extensionControlled.${settingName}`);
+  let image = document.createElement("image");
+  const defaultIcon = "chrome://mozapps/skin/extensions/extensionGeneric.svg";
+  image.setAttribute("src", addon.iconURL || defaultIcon);
+  image.classList.add("extension-controlled-icon");
+  let addonBit = document.createDocumentFragment();
+  addonBit.appendChild(image);
+  addonBit.appendChild(document.createTextNode(" " + addon.name));
+  let fragment = BrowserUtils.getLocalizedFragment(document, msg, addonBit);
+  description.appendChild(fragment);
+
+  if (elements.button) {
+    elements.button.hidden = false;
+  }
+
+  // Show the controlling extension row and hide the old label.
+  elements.section.hidden = false;
+}
+
+function hideControllingExtension(settingName) {
+  let elements = getControllingExtensionEls(settingName);
+  elements.section.hidden = true;
+  if (elements.button) {
+    elements.button.hidden = true;
+  }
+}
+
+function showEnableExtensionMessage(settingName) {
+  let elements = getControllingExtensionEls(settingName);
+
+  elements.button.hidden = true;
+  elements.section.classList.add("extension-controlled-disabled");
+  let icon = url => {
+    let img = document.createElement("image");
+    img.src = url;
+    img.className = "extension-controlled-icon";
+    return img;
+  };
+  let addonIcon = icon("chrome://mozapps/skin/extensions/extensionGeneric-16.svg");
+  let toolbarIcon = icon("chrome://browser/skin/menu.svg");
+  let message = document.getElementById("bundlePreferences")
+                        .getString("extensionControlled.enable");
+  let frag = BrowserUtils.getLocalizedFragment(document, message, addonIcon, toolbarIcon);
+  elements.description.innerHTML = "";
+  elements.description.appendChild(frag);
+  let dismissButton = document.createElement("image");
+  dismissButton.setAttribute("class", "extension-controlled-icon close-icon");
+  dismissButton.addEventListener("click", function dismissHandler() {
+    hideControllingExtension(settingName);
+    dismissButton.removeEventListener("click", dismissHandler);
+  });
+  elements.description.appendChild(dismissButton);
+}
+
+function makeDisableControllingExtension(type, settingName) {
+  return async function disableExtension() {
+    let {id} = await getControllingExtensionInfo(type, settingName);
+    let addon = await AddonManager.getAddonByID(id);
+    addon.userDisabled = true;
+  };
+}

--- a/browser/components/preferences/in-content/preferences.xul
+++ b/browser/components/preferences/in-content/preferences.xul
@@ -103,18 +103,16 @@
               href="chrome://browser/skin/settings.svg"/>
 
   <script type="application/javascript"
           src="chrome://browser/content/utilityOverlay.js"/>
   <script type="application/javascript"
           src="chrome://global/content/preferencesBindings.js"/>
   <script type="application/javascript"
           src="chrome://browser/content/preferences/in-content/preferences.js"/>
-  <script type="application/javascript"
-          src="chrome://browser/content/preferences/in-content/extensionControlled.js"/>
   <script src="chrome://browser/content/preferences/in-content/findInPage.js"/>
   <script src="chrome://browser/content/preferences/in-content/subdialogs.js"/>
 
   <stringbundle id="bundleBrand"
                 src="chrome://branding/locale/brand.properties"/>
   <stringbundle id="bundlePreferences"
                 src="chrome://browser/locale/preferences/preferences.properties"/>
   <stringbundle id="pkiBundle"

--- a/browser/components/preferences/in-content/privacy.js
+++ b/browser/components/preferences/in-content/privacy.js
@@ -1,13 +1,12 @@
 /* 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/. */
 
-/* import-globals-from extensionControlled.js */
 /* import-globals-from preferences.js */
 
 /* FIXME: ESlint globals workaround should be removed once bug 1395426 gets fixed */
 /* globals DownloadUtils, LoadContextInfo */
 
 ChromeUtils.import("resource://gre/modules/AppConstants.jsm");
 ChromeUtils.import("resource://gre/modules/PluralForm.jsm");
 

--- a/browser/components/preferences/in-content/search.js
+++ b/browser/components/preferences/in-content/search.js
@@ -1,13 +1,12 @@
 /* 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/. */
 
-/* import-globals-from extensionControlled.js */
 /* import-globals-from preferences.js */
 
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
 ChromeUtils.defineModuleGetter(this, "PlacesUtils",
                                "resource://gre/modules/PlacesUtils.jsm");
 ChromeUtils.defineModuleGetter(this, "ExtensionSettingsStore",
                                "resource://gre/modules/ExtensionSettingsStore.jsm");
 

--- a/browser/components/preferences/in-content/tests/browser_extension_controlled.js
+++ b/browser/components/preferences/in-content/tests/browser_extension_controlled.js
@@ -1,18 +1,15 @@
 /* eslint-env webextensions */
 
-const PROXY_PREF = "network.proxy.type";
-
 ChromeUtils.defineModuleGetter(this, "ExtensionSettingsStore",
                                "resource://gre/modules/ExtensionSettingsStore.jsm");
 XPCOMUtils.defineLazyServiceGetter(this, "aboutNewTabService",
                                    "@mozilla.org/browser/aboutnewtab-service;1",
                                    "nsIAboutNewTabService");
-XPCOMUtils.defineLazyPreferenceGetter(this, "proxyType", PROXY_PREF);
 
 const TEST_DIR = gTestPath.substr(0, gTestPath.lastIndexOf("/"));
 const CHROME_URL_ROOT = TEST_DIR + "/";
 
 function getSupportsFile(path) {
   let cr = Cc["@mozilla.org/chrome/chrome-registry;1"]
     .getService(Ci.nsIChromeRegistry);
   let uri = Services.io.newURI(CHROME_URL_ROOT + path);
@@ -46,47 +43,36 @@ function waitForMutation(target, opts, c
         observer.disconnect();
         resolve();
       }
     });
     observer.observe(target, opts);
   });
 }
 
-function waitForMessageChange(element, cb, opts = { attributes: true, attributeFilter: ["hidden"] }) {
-  return waitForMutation(element, opts, cb);
+function waitForMessageChange(id, cb, opts = { attributes: true, attributeFilter: ["hidden"] }) {
+  // eslint-disable-next-line mozilla/no-cpows-in-tests
+  return waitForMutation(gBrowser.contentDocument.getElementById(id), opts, cb);
 }
 
-// eslint-disable-next-line mozilla/no-cpows-in-tests
-function getElement(id, doc = gBrowser.contentDocument) {
-  return doc.getElementById(id);
-}
-
-function waitForMessageHidden(messageId, doc) {
-  return waitForMessageChange(getElement(messageId, doc), target => target.hidden);
+function waitForMessageHidden(messageId) {
+  return waitForMessageChange(messageId, target => target.hidden);
 }
 
-function waitForMessageShown(messageId, doc) {
-  return waitForMessageChange(getElement(messageId, doc), target => !target.hidden);
+function waitForMessageShown(messageId) {
+  return waitForMessageChange(messageId, target => !target.hidden);
 }
 
-function waitForEnableMessage(messageId, doc) {
+function waitForEnableMessage(messageId) {
   return waitForMessageChange(
-    getElement(messageId, doc),
+    messageId,
     target => target.classList.contains("extension-controlled-disabled"),
     { attributeFilter: ["class"], attributes: true });
 }
 
-function waitForMessageContent(messageId, content, doc) {
-  return waitForMessageChange(
-    getElement(messageId, doc),
-    target => target.textContent === content,
-    { childList: true });
-}
-
 add_task(async function testExtensionControlledHomepage() {
   await openPreferencesViaOpenPreferencesAPI("paneGeneral", {leaveOpen: true});
   // eslint-disable-next-line mozilla/no-cpows-in-tests
   let doc = gBrowser.contentDocument;
   is(gBrowser.currentURI.spec, "about:preferences#general",
      "#general should be in the URI for about:preferences");
   let homepagePref = () => Services.prefs.getCharPref("browser.startup.homepage");
   let originalHomepagePref = homepagePref();
@@ -101,17 +87,17 @@ add_task(async function testExtensionCon
   // Install an extension that will set the homepage.
   await installAddon("set_homepage.xpi");
   await waitForMessageShown("browserHomePageExtensionContent");
 
   // The homepage has been set by the extension, the user is notified and it isn't editable.
   let controlledLabel = controlledContent.querySelector("description");
   is(homepagePref(), extensionHomepage, "homepage is set by extension");
   // There are two spaces before "set_homepage" because it's " <image /> set_homepage".
-  is(controlledLabel.textContent, "An extension,  set_homepage, is controlling your home page.",
+  is(controlledLabel.textContent, "An extension,  set_homepage, controls your home page.",
      "The user is notified that an extension is controlling the homepage");
   is(controlledContent.hidden, false, "The extension controlled row is hidden");
   is(doc.getElementById("browserHomePage").disabled, true, "The homepage input is disabled");
 
   // Disable the extension.
   let enableMessageShown = waitForEnableMessage(controlledContent.id);
   doc.getElementById("disableHomePageExtension").click();
   await enableMessageShown;
@@ -291,17 +277,17 @@ add_task(async function testExtensionCon
   await installAddon("set_newtab.xpi");
 
   await waitForMessageShown("browserNewTabExtensionContent");
 
   // The new tab page has been set by the extension and the user is notified.
   let controlledLabel = controlledContent.querySelector("description");
   ok(aboutNewTabService.newTabURL.startsWith("moz-extension:"), "new tab url is set by extension");
   // There are two spaces before "set_newtab" because it's " <image /> set_newtab".
-  is(controlledLabel.textContent, "An extension,  set_newtab, is controlling your New Tab page.",
+  is(controlledLabel.textContent, "An extension,  set_newtab, controls your New Tab page.",
      "The user is notified that an extension is controlling the new tab page");
   is(controlledContent.hidden, false, "The extension controlled row is hidden");
 
   // Disable the extension.
   doc.getElementById("disableNewTabExtension").click();
 
   // Verify the user is notified how to enable the extension.
   await waitForEnableMessage(controlledContent.id);
@@ -613,198 +599,8 @@ add_task(async function testExtensionCon
   // ExtensionPreferencesManager to clean up properly.
   // TODO: BUG 1408226
   await reEnableExtension(addon);
 
   await extension.unload();
 
   await BrowserTestUtils.removeTab(gBrowser.selectedTab);
 });
-
-add_task(async function testExtensionControlledProxyConfig() {
-  const proxySvc = Ci.nsIProtocolProxyService;
-  const PROXY_DEFAULT = proxySvc.PROXYCONFIG_SYSTEM;
-  const EXTENSION_ID = "@set_proxy";
-  const CONTROLLED_SECTION_ID = "proxyExtensionContent";
-  const CONTROLLED_BUTTON_ID = "disableProxyExtension";
-  const CONNECTION_SETTINGS_DESC_ID = "connectionSettingsDescription";
-  const PANEL_URL = "chrome://browser/content/preferences/connection.xul";
-
-  await SpecialPowers.pushPrefEnv({"set": [[PROXY_PREF, PROXY_DEFAULT]]});
-
-  function background() {
-    browser.browserSettings.proxyConfig.set({value: {proxyType: "none"}});
-  }
-
-  function expectedConnectionSettingsMessage(doc, isControlled) {
-    let brandShortName = doc.getElementById("bundleBrand").getString("brandShortName");
-    return isControlled ?
-      `An extension,  set_proxy, is controlling how ${brandShortName} connects to the internet.` :
-      `Configure how ${brandShortName} connects to the internet.`;
-  }
-
-  function connectionSettingsMessagePromise(doc, isControlled) {
-    return waitForMessageContent(
-      CONNECTION_SETTINGS_DESC_ID,
-      expectedConnectionSettingsMessage(doc, isControlled)
-    );
-  }
-
-  function verifyState(doc, isControlled) {
-    let isPanel = doc.getElementById(CONTROLLED_BUTTON_ID);
-    let brandShortName = doc.getElementById("bundleBrand").getString("brandShortName");
-    is(proxyType === proxySvc.PROXYCONFIG_DIRECT, isControlled,
-      "Proxy pref is set to the expected value.");
-
-    if (isPanel) {
-      let controlledSection = doc.getElementById(CONTROLLED_SECTION_ID);
-
-      is(controlledSection.hidden, !isControlled, "The extension controlled row's visibility is as expected.");
-      if (isPanel) {
-        is(doc.getElementById(CONTROLLED_BUTTON_ID).hidden, !isControlled,
-           "The disable extension button's visibility is as expected.");
-      }
-      if (isControlled) {
-        let controlledDesc = controlledSection.querySelector("description");
-        // There are two spaces before "set_proxy" because it's " <image /> set_proxy".
-        is(controlledDesc.textContent, `An extension,  set_proxy, is controlling how ${brandShortName} connects to the internet.`,
-          "The user is notified that an extension is controlling proxy settings.");
-      }
-      function getProxyControls() {
-        let controlGroup = doc.getElementById("networkProxyType");
-        return [
-          ...controlGroup.querySelectorAll(":scope > radio"),
-          ...controlGroup.querySelectorAll("label"),
-          ...controlGroup.querySelectorAll("textbox"),
-          ...controlGroup.querySelectorAll("checkbox"),
-          ...doc.querySelectorAll("#networkProxySOCKSVersion > radio"),
-          ...doc.querySelectorAll("#ConnectionsDialogPane > checkbox"),
-        ];
-      }
-      let controlState = isControlled ? "disabled" : "enabled";
-      for (let element of getProxyControls()) {
-        is(element.disabled, isControlled, `Proxy controls are ${controlState}.`);
-      }
-    } else {
-      is(doc.getElementById(CONNECTION_SETTINGS_DESC_ID).textContent,
-         expectedConnectionSettingsMessage(doc, isControlled),
-         "The connection settings description is as expected.");
-    }
-  }
-
-  async function disableViaClick() {
-    let sectionId = CONTROLLED_SECTION_ID;
-    let controlledSection = panelDoc.getElementById(sectionId);
-
-    let enableMessageShown = waitForEnableMessage(sectionId, panelDoc);
-    panelDoc.getElementById(CONTROLLED_BUTTON_ID).click();
-    await enableMessageShown;
-
-    // The user is notified how to enable the extension.
-    let controlledDesc = controlledSection.querySelector("description");
-    is(controlledDesc.textContent, "To enable the extension go to  Add-ons in the  menu.",
-       "The user is notified of how to enable the extension again");
-
-    // The user can dismiss the enable instructions.
-    let hidden = waitForMessageHidden(sectionId, panelDoc);
-    controlledSection.querySelector("image:last-of-type").click();
-    return hidden;
-  }
-
-  async function reEnableExtension(addon) {
-    let messageChanged = connectionSettingsMessagePromise(mainDoc, true);
-    addon.userDisabled = false;
-    await messageChanged;
-  }
-
-  async function openProxyPanel() {
-    let panel = await openAndLoadSubDialog(PANEL_URL);
-    let closingPromise = waitForEvent(panel.document.documentElement, "dialogclosing");
-    ok(panel, "Proxy panel opened.");
-    return {panel, closingPromise};
-  }
-
-  async function closeProxyPanel(panelObj) {
-    panelObj.panel.document.documentElement.cancelDialog();
-    let panelClosingEvent = await panelObj.closingPromise;
-    ok(panelClosingEvent, "Proxy panel closed.");
-  }
-
-  await openPreferencesViaOpenPreferencesAPI("paneGeneral", {leaveOpen: true});
-  // eslint-disable-next-line mozilla/no-cpows-in-tests
-  let mainDoc = gBrowser.contentDocument;
-
-  is(gBrowser.currentURI.spec, "about:preferences#general",
-   "#general should be in the URI for about:preferences");
-
-  verifyState(mainDoc, false);
-
-  // Open the connections panel.
-  let panelObj = await openProxyPanel();
-  let panelDoc = panelObj.panel.document;
-
-  verifyState(panelDoc, false);
-
-  await closeProxyPanel(panelObj);
-
-  verifyState(mainDoc, false);
-
-  // Install an extension that sets Tracking Protection.
-  let extension = ExtensionTestUtils.loadExtension({
-    useAddonManager: "permanent",
-    manifest: {
-      name: "set_proxy",
-      applications: {gecko: {id: EXTENSION_ID}},
-      permissions: ["browserSettings"],
-    },
-    background,
-  });
-
-  let messageChanged = connectionSettingsMessagePromise(mainDoc, true);
-  await extension.startup();
-  await messageChanged;
-  let addon = await AddonManager.getAddonByID(EXTENSION_ID);
-
-  verifyState(mainDoc, true);
-  messageChanged = connectionSettingsMessagePromise(mainDoc, false);
-
-  panelObj = await openProxyPanel();
-  panelDoc = panelObj.panel.document;
-
-  verifyState(panelDoc, true);
-
-  await disableViaClick();
-
-  verifyState(panelDoc, false);
-
-  await closeProxyPanel(panelObj);
-  await messageChanged;
-
-  verifyState(mainDoc, false);
-
-  await reEnableExtension(addon);
-
-  verifyState(mainDoc, true);
-  messageChanged = connectionSettingsMessagePromise(mainDoc, false);
-
-  panelObj = await openProxyPanel();
-  panelDoc = panelObj.panel.document;
-
-  verifyState(panelDoc, true);
-
-  await disableViaClick();
-
-  verifyState(panelDoc, false);
-
-  await closeProxyPanel(panelObj);
-  await messageChanged;
-
-  verifyState(mainDoc, false);
-
-  // Enable the extension so we get the UNINSTALL event, which is needed by
-  // ExtensionPreferencesManager to clean up properly.
-  // TODO: BUG 1408226
-  await reEnableExtension(addon);
-
-  await extension.unload();
-
-  await BrowserTestUtils.removeTab(gBrowser.selectedTab);
-});

--- a/browser/locales/en-US/chrome/browser/preferences/advanced.dtd
+++ b/browser/locales/en-US/chrome/browser/preferences/advanced.dtd
@@ -40,17 +40,17 @@ available. -->
 <!ENTITY alwaysSubmitCrashReports1.label  "Allow &brandShortName; to send crash reports to Mozilla">
 <!ENTITY alwaysSubmitCrashReports1.accesskey "c">
 <!ENTITY crashReporterLearnMore.label    "Learn more">
 
 <!ENTITY networkTab.label                "Network">
 
 <!ENTITY networkProxy.label              "Network Proxy">
 
-<!ENTITY connectionSettingsLearnMore.label "Learn more">
+<!ENTITY connectionDesc.label            "Configure how &brandShortName; connects to the Internet">
 <!ENTITY connectionSettings.label        "Settings…">
 <!ENTITY connectionSettings.accesskey    "e">
 
 <!ENTITY httpCache.label                 "Cached Web Content">
 
 <!--  Site Data section manages sites using Storage API and is under Network -->
 <!ENTITY siteData.label                  "Site Data">
 <!ENTITY clearSiteData.label             "Clear All Data">

--- a/browser/locales/en-US/chrome/browser/preferences/connection.dtd
+++ b/browser/locales/en-US/chrome/browser/preferences/connection.dtd
@@ -2,17 +2,17 @@
    - 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/. -->
 
 
 <!ENTITY  connectionsDialog.title       "Connection Settings">
 <!ENTITY  window.width2                 "49em">
 <!ENTITY  window.macWidth2              "44em">
 
-<!ENTITY  proxyTitle.label2             "Configure Proxy Access to the Internet">
+<!ENTITY  proxyTitle.label              "Configure Proxies to Access the Internet">
 <!ENTITY  noProxyTypeRadio.label        "No proxy">
 <!ENTITY  noProxyTypeRadio.accesskey    "y">
 <!ENTITY  systemTypeRadio.label         "Use system proxy settings">
 <!ENTITY  systemTypeRadio.accesskey     "u">
 <!ENTITY  WPADTypeRadio.label           "Auto-detect proxy settings for this network">
 <!ENTITY  WPADTypeRadio.accesskey       "w">
 <!ENTITY  manualTypeRadio2.label        "Manual proxy configuration">
 <!ENTITY  manualTypeRadio2.accesskey    "m">

--- a/browser/locales/en-US/chrome/browser/preferences/preferences.properties
+++ b/browser/locales/en-US/chrome/browser/preferences/preferences.properties
@@ -270,43 +270,33 @@ searchResults.needHelp3=Need help? Visit
 # LOCALIZATION NOTE (searchResults.needHelpSupportLink): %S will be replaced with the browser name.
 searchResults.needHelpSupportLink=%S Support
 
 # LOCALIZATION NOTE %S is the default value of the `dom.ipc.processCount` pref.
 defaultContentProcessCount=%S (default)
 
 # LOCALIZATION NOTE (extensionControlled.homepage_override):
 # This string is shown to notify the user that their home page is being controlled by an extension.
-extensionControlled.homepage_override = An extension, %S, is controlling your home page.
+extensionControlled.homepage_override = An extension, %S, controls your home page.
 
 # LOCALIZATION NOTE (extensionControlled.newTabURL):
 # This string is shown to notify the user that their new tab page is being controlled by an extension.
-extensionControlled.newTabURL = An extension, %S, is controlling your New Tab page.
+extensionControlled.newTabURL = An extension, %S, controls your New Tab page.
 
 # LOCALIZATION NOTE (extensionControlled.defaultSearch):
 # This string is shown to notify the user that the default search engine is being controlled
 # by an extension. %S is the icon and name of the extension.
 extensionControlled.defaultSearch = An extension, %S, has set your default search engine.
 
 # LOCALIZATION NOTE (extensionControlled.privacy.containers):
 # This string is shown to notify the user that Container Tabs are being enabled by an extension
 # %S is the container addon controlling it
 extensionControlled.privacy.containers = An extension, %S, requires Container Tabs.
 
 # LOCALIZATION NOTE (extensionControlled.websites.trackingProtectionMode):
 # This string is shown to notify the user that their tracking protection preferences are being controlled by an extension.
 extensionControlled.websites.trackingProtectionMode = An extension, %S, is controlling tracking protection.
 
-# LOCALIZATION NOTE (extensionControlled.proxyConfig):
-# This string is shown to notify the user that their proxy configuration preferences are being controlled by an extension.
-# %1$S is the icon and name of the extension.
-# %2$S is the brandShortName from brand.properties (for example "Nightly")
-extensionControlled.proxyConfig = An extension, %1$S, is controlling how %2$S connects to the internet.
-
 # LOCALIZATION NOTE (extensionControlled.enable):
 # %1$S is replaced with the icon for the add-ons menu.
 # %2$S is replaced with the icon for the toolbar menu.
 # This string is shown to notify the user how to enable an extension that they disabled.
 extensionControlled.enable = To enable the extension go to %1$S Add-ons in the %2$S menu.
-
-# LOCALIZATION NOTE (connectionDesc.label):
-# %S is the brandShortName from brand.properties (for example "Nightly")
-connectionDesc.label = Configure how %S connects to the internet.