--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -27,17 +27,16 @@ module.exports = {
   }, {
     // XXX Bug 1421969. These files/directories are still being fixed,
     // so turn off mozilla/use-services for them for now.
     "files": [
       "accessible/**",
       // Browser: Bug 1421379
       "browser/extensions/shield-recipe-client/test/browser/head.js",
       "browser/modules/offlineAppCache.jsm",
-      "chrome/**",
       "devtools/**",
       "dom/indexedDB/**",
       "dom/media/**",
       "extensions/pref/**",
       "mobile/android/**",
       "security/**",
       "testing/**",
       "tools/profiler/**",

--- a/chrome/test/unit/head_crtestutils.js
+++ b/chrome/test/unit/head_crtestutils.js
@@ -1,13 +1,12 @@
 const XULAPPINFO_CONTRACTID = "@mozilla.org/xre/app-info;1";
 const XULAPPINFO_CID = Components.ID("{4ba645d3-be6f-40d6-a42a-01b2f40091b8}");
 
-var Cc = Components.classes;
-var Ci = Components.interfaces;
-var Cr = Components.results;
+let {classes: Cc, interfaces: Ci, results: Cr, utils: Cu} = Components;
 
+Cu.import("resource://gre/modules/Services.jsm");
 
 function registerManifests(manifests) {
   var reg = Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
   for (var manifest of manifests)
     reg.autoRegister(manifest);
 }

--- a/chrome/test/unit/test_bug292789.js
+++ b/chrome/test/unit/test_bug292789.js
@@ -4,28 +4,25 @@
  */
 
 const MANIFESTS = [
   do_get_file("data/test_bug292789.manifest")
 ];
 
 registerManifests(MANIFESTS);
 
-var gIOS;
 var gCR;
 
 function check_accessibility(spec, desired) {
-  var uri = gIOS.newURI(spec);
+  var uri = Services.io.newURI(spec);
   var actual = gCR.allowContentToAccess(uri);
   do_check_eq(desired, actual);
 }
 
 function run_test() {
-  gIOS = Cc["@mozilla.org/network/io-service;1"].
-    getService(Ci.nsIIOService);
   gCR = Cc["@mozilla.org/chrome/chrome-registry;1"].
     getService(Ci.nsIXULChromeRegistry);
   gCR.checkForNewChrome();
 
   check_accessibility("chrome://test1/content/", false);
   check_accessibility("chrome://test1/content/foo.js", false);
   check_accessibility("chrome://test2/content/", true);
   check_accessibility("chrome://test2/content/foo.js", true);

--- a/chrome/test/unit/test_bug380398.js
+++ b/chrome/test/unit/test_bug380398.js
@@ -13,37 +13,35 @@ registerManifests(MANIFESTS);
 Components.utils.import("resource://testing-common/AppInfo.jsm", this);
 updateAppInfo({
   name: "XPCShell",
   id: "{39885e5f-f6b4-4e2a-87e5-6259ecf79011}",
   version: "5",
   platformVersion: "1.9",
 });
 
-var gIOS = Cc["@mozilla.org/network/io-service;1"]
-            .getService(Ci.nsIIOService);
 var chromeReg = Cc["@mozilla.org/chrome/chrome-registry;1"]
                  .getService(Ci.nsIChromeRegistry);
 chromeReg.checkForNewChrome();
 
-var target = gIOS.newFileURI(do_get_file("data"));
+var target = Services.io.newFileURI(do_get_file("data"));
 target = target.spec + "test/test.xul";
 
 function test_succeeded_mapping(namespace) {
-  var uri = gIOS.newURI("chrome://" + namespace + "/content/test.xul");
+  var uri = Services.io.newURI("chrome://" + namespace + "/content/test.xul");
   try {
     var result = chromeReg.convertChromeURL(uri);
     do_check_eq(result.spec, target);
   } catch (ex) {
     do_throw(namespace);
   }
 }
 
 function test_failed_mapping(namespace) {
-  var uri = gIOS.newURI("chrome://" + namespace + "/content/test.xul");
+  var uri = Services.io.newURI("chrome://" + namespace + "/content/test.xul");
   try {
     chromeReg.convertChromeURL(uri);
     do_throw(namespace);
   } catch (ex) {
   }
 }
 
 function run_test() {

--- a/chrome/test/unit/test_bug397073.js
+++ b/chrome/test/unit/test_bug397073.js
@@ -13,37 +13,35 @@ registerManifests(MANIFESTS);
 Components.utils.import("resource://testing-common/AppInfo.jsm", this);
 updateAppInfo({
   name: "XPCShell",
   ID: "{39885e5f-f6b4-4e2a-87e5-6259ecf79011}",
   version: "5",
   platformVersion: "1.9",
 });
 
-var gIOS = Cc["@mozilla.org/network/io-service;1"]
-            .getService(Ci.nsIIOService);
 var chromeReg = Cc["@mozilla.org/chrome/chrome-registry;1"]
                  .getService(Ci.nsIChromeRegistry);
 chromeReg.checkForNewChrome();
 
-var target = gIOS.newFileURI(do_get_file("data"));
+var target = Services.io.newFileURI(do_get_file("data"));
 target = target.spec + "test/test.xul";
 
 function test_succeeded_mapping(namespace) {
-  var uri = gIOS.newURI("chrome://" + namespace + "/content/test.xul");
+  var uri = Services.io.newURI("chrome://" + namespace + "/content/test.xul");
   try {
     var result = chromeReg.convertChromeURL(uri);
     do_check_eq(result.spec, target);
   } catch (ex) {
     do_throw(namespace);
   }
 }
 
 function test_failed_mapping(namespace) {
-  var uri = gIOS.newURI("chrome://" + namespace + "/content/test.xul");
+  var uri = Services.io.newURI("chrome://" + namespace + "/content/test.xul");
   try {
     chromeReg.convertChromeURL(uri);
     do_throw(namespace);
   } catch (ex) {
   }
 }
 
 function run_test() {

--- a/chrome/test/unit/test_bug399707.js
+++ b/chrome/test/unit/test_bug399707.js
@@ -12,37 +12,35 @@ registerManifests(MANIFESTS);
 Components.utils.import("resource://testing-common/AppInfo.jsm", this);
 updateAppInfo({
   name: "XPCShell",
   ID: "{39885e5f-f6b4-4e2a-87e5-6259ecf79011}",
   version: "5",
   platformVersion: "1.9",
 });
 
-var gIOS = Cc["@mozilla.org/network/io-service;1"]
-            .getService(Ci.nsIIOService);
 var chromeReg = Cc["@mozilla.org/chrome/chrome-registry;1"]
                  .getService(Ci.nsIChromeRegistry);
 chromeReg.checkForNewChrome();
 
-var target = gIOS.newFileURI(do_get_file("data"));
+var target = Services.io.newFileURI(do_get_file("data"));
 target = target.spec + "test/test.xul";
 
 function test_succeeded_mapping(namespace) {
-  var uri = gIOS.newURI("chrome://" + namespace + "/content/test.xul");
+  var uri = Services.io.newURI("chrome://" + namespace + "/content/test.xul");
   try {
     var result = chromeReg.convertChromeURL(uri);
     do_check_eq(result.spec, target);
   } catch (ex) {
     do_throw(namespace);
   }
 }
 
 function test_failed_mapping(namespace) {
-  var uri = gIOS.newURI("chrome://" + namespace + "/content/test.xul");
+  var uri = Services.io.newURI("chrome://" + namespace + "/content/test.xul");
   try {
     chromeReg.convertChromeURL(uri);
     do_throw(namespace);
   } catch (ex) {
   }
 }
 
 function run_test() {

--- a/chrome/test/unit/test_bug401153.js
+++ b/chrome/test/unit/test_bug401153.js
@@ -12,40 +12,38 @@ registerManifests(MANIFESTS);
 Components.utils.import("resource://testing-common/AppInfo.jsm", this);
 updateAppInfo({
   name: "XPCShell",
   ID: "{39885e5f-f6b4-4e2a-87e5-6259ecf79011}",
   version: "5",
   platformVersion: "1.9",
 });
 
-var gIOS = Cc["@mozilla.org/network/io-service;1"]
-            .getService(Ci.nsIIOService);
 var chromeReg = Cc["@mozilla.org/chrome/chrome-registry;1"]
                  .getService(Ci.nsIChromeRegistry);
 chromeReg.checkForNewChrome();
 
-var rph = gIOS.getProtocolHandler("resource")
+var rph = Services.io.getProtocolHandler("resource")
               .QueryInterface(Ci.nsIResProtocolHandler);
 
 function test_succeeded_mapping(namespace, target) {
   try {
     do_check_true(rph.hasSubstitution(namespace));
-    var uri = gIOS.newURI("resource://" + namespace);
+    var uri = Services.io.newURI("resource://" + namespace);
     dump("### checking for " + target + ", getting " + rph.resolveURI(uri) + "\n");
     do_check_eq(rph.resolveURI(uri), target);
   } catch (ex) {
     dump(ex + "\n");
     do_throw(namespace);
   }
 }
 
 function test_failed_mapping(namespace) {
   do_check_false(rph.hasSubstitution(namespace));
 }
 
 function run_test() {
-  var data = gIOS.newFileURI(do_get_file("data")).spec;
+  var data = Services.io.newFileURI(do_get_file("data")).spec;
   test_succeeded_mapping("test1", data + "test1/");
   test_succeeded_mapping("test3", "jar:" + data + "test3.jar!/resources/");
   test_failed_mapping("test4");
   test_succeeded_mapping("test5", data + "test5/");
 }

--- a/chrome/test/unit/test_bug415367.js
+++ b/chrome/test/unit/test_bug415367.js
@@ -1,22 +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 gIOS = Cc["@mozilla.org/network/io-service;1"]
-            .getService(Ci.nsIIOService);
-
 function test_uri(obj) {
   var uri = null;
   var failed = false;
   var message = "";
   try {
-    uri = gIOS.newURI(obj.uri);
+    uri = Services.io.newURI(obj.uri);
     if (!obj.result) {
       failed = true;
       message = obj.uri + " should not be accepted as a valid URI";
     }
   } catch (ex) {
     if (obj.result) {
       failed = true;
       message = obj.uri + " should be accepted as a valid URI";

--- a/chrome/test/unit/test_bug564667.js
+++ b/chrome/test/unit/test_bug564667.js
@@ -1,58 +1,55 @@
 /* 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/.
  */
 
 const UNPACKAGED_ADDON = do_get_file("data/test_bug564667");
 const PACKAGED_ADDON = do_get_file("data/test_bug564667.xpi");
 
-var gIOS = Cc["@mozilla.org/network/io-service;1"].
-           getService(Ci.nsIIOService);
-
 var gCR = Cc["@mozilla.org/chrome/chrome-registry;1"].
           getService(Ci.nsIChromeRegistry).
           QueryInterface(Ci.nsIXULOverlayProvider);
 
 /*
  * Checks that a mapping was added
  */
 function test_mapping(chromeURL, target) {
-  var uri = gIOS.newURI(chromeURL);
+  var uri = Services.io.newURI(chromeURL);
 
   try {
     var result = gCR.convertChromeURL(uri);
     do_check_eq(result.spec, target);
   } catch (ex) {
     do_throw(chromeURL + " not Registered");
   }
 }
 
 /*
  * Checks that a mapping was removed
  */
 function test_removed_mapping(chromeURL, target) {
-  var uri = gIOS.newURI(chromeURL);
+  var uri = Services.io.newURI(chromeURL);
   try {
     gCR.convertChromeURL(uri);
     do_throw(chromeURL + " not removed");
   } catch (ex) {
     // This should throw
   }
 }
 
 /*
  * Checks if any overlay was added after loading
  * the manifest files
  *
  * @param type The type of overlay: overlay|style
  */
 function test_no_overlays(chromeURL, target, type = "overlay") {
-  var uri = gIOS.newURI(chromeURL);
+  var uri = Services.io.newURI(chromeURL);
   var overlays = (type == "overlay") ?
       gCR.getXULOverlays(uri) : gCR.getStyleOverlays(uri);
 
   // We shouldn't be allowed to register overlays nor styles
   if (overlays.hasMoreElements()) {
     if (type == "styles")
       do_throw("Style Registered: " + chromeURL);
     else
@@ -104,13 +101,13 @@ function testManifest(manifestPath, base
 
   // Test Removing Manifest URL
   test_removed_mapping("chrome://test2/content", baseURI + "test/test2.xul");
   test_removed_mapping("chrome://test2/locale", baseURI + "test/test2.dtd");
 }
 
 function run_test() {
   // Test an unpackaged addon
-  testManifest(UNPACKAGED_ADDON, gIOS.newFileURI(UNPACKAGED_ADDON).spec);
+  testManifest(UNPACKAGED_ADDON, Services.io.newFileURI(UNPACKAGED_ADDON).spec);
 
   // Test a packaged addon
-  testManifest(PACKAGED_ADDON, "jar:" + gIOS.newFileURI(PACKAGED_ADDON).spec + "!/");
+  testManifest(PACKAGED_ADDON, "jar:" + Services.io.newFileURI(PACKAGED_ADDON).spec + "!/");
 }

--- a/chrome/test/unit/test_bug848297.js
+++ b/chrome/test/unit/test_bug848297.js
@@ -13,20 +13,16 @@ Components.utils.import("resource://gre/
 
 registerManifests(MANIFESTS);
 
 var chromeReg = Cc["@mozilla.org/chrome/chrome-registry;1"]
                 .getService(Ci.nsIXULChromeRegistry)
                 .QueryInterface(Ci.nsIToolkitChromeRegistry);
 chromeReg.checkForNewChrome();
 
-var prefService = Cc["@mozilla.org/preferences-service;1"]
-                  .getService(Ci.nsIPrefService)
-                  .QueryInterface(Ci.nsIPrefBranch);
-
 function enum_to_array(strings) {
   let rv = [];
   while (strings.hasMore()) {
     rv.push(strings.getNext());
   }
   rv.sort();
   return rv;
 }
@@ -36,14 +32,14 @@ function run_test() {
   // without override
   Services.locale.setRequestedLocales(["de"]);
   do_check_eq(chromeReg.getSelectedLocale("basepack"), "en-US");
   do_check_eq(chromeReg.getSelectedLocale("overpack"), "de");
   do_check_matches(enum_to_array(chromeReg.getLocalesForPackage("basepack")),
                    ["en-US", "fr"]);
 
   // with override
-  prefService.setCharPref("chrome.override_package.basepack", "overpack");
+  Services.prefs.setCharPref("chrome.override_package.basepack", "overpack");
   do_check_eq(chromeReg.getSelectedLocale("basepack"), "de");
   do_check_matches(enum_to_array(chromeReg.getLocalesForPackage("basepack")),
                    ["de", "en-US"]);
 
 }

--- a/chrome/test/unit/test_crlf.js
+++ b/chrome/test/unit/test_crlf.js
@@ -1,14 +1,12 @@
 registerManifests([do_get_file("data/test_crlf.manifest")]);
 
 function run_test() {
   let cr = Cc["@mozilla.org/chrome/chrome-registry;1"].
     getService(Ci.nsIChromeRegistry);
 
-  let ios = Cc["@mozilla.org/network/io-service;1"].
-    getService(Ci.nsIIOService);
-  let sourceURI = ios.newURI("chrome://test_crlf/content/");
+  let sourceURI = Services.io.newURI("chrome://test_crlf/content/");
   // this throws for packages that are not registered
   let file = cr.convertChromeURL(sourceURI).QueryInterface(Ci.nsIFileURL).file;
 
   do_check_true(file.equals(do_get_file("data/test_crlf.xul", true)));
 }

--- a/chrome/test/unit/test_data_protocol_registration.js
+++ b/chrome/test/unit/test_data_protocol_registration.js
@@ -73,19 +73,17 @@ function run_test() {
   let cr = Cc["@mozilla.org/chrome/chrome-registry;1"].
            getService(Ci.nsIChromeRegistry);
   cr.checkForNewChrome();
 
   // Check that our override worked
   let expectedURI = "data:application/vnd.mozilla.xul+xml,";
   let sourceURI = "chrome://good-package/content/test.xul";
   try {
-    let ios = Cc["@mozilla.org/network/io-service;1"].
-              getService(Ci.nsIIOService);
-    sourceURI = ios.newURI(sourceURI);
+    sourceURI = Services.io.newURI(sourceURI);
     // this throws for packages that are not registered
     let uri = cr.convertChromeURL(sourceURI).spec;
 
     do_check_eq(expectedURI, uri);
   } catch (e) {
     dump(e + "\n");
     do_throw("Should have registered our URI!");
   }

--- a/chrome/test/unit/test_no_remote_registration.js
+++ b/chrome/test/unit/test_no_remote_registration.js
@@ -173,23 +173,21 @@ function run_test() {
           sourceURI = "chrome://good-package/content/override-" +
                       protocol.scheme + ".xul";
           break;
         case "resource":
           sourceURI = "resource://" + protocol.scheme + "/";
           break;
       }
       try {
-        let ios = Cc["@mozilla.org/network/io-service;1"].
-                  getService(Ci.nsIIOService);
-        sourceURI = ios.newURI(sourceURI);
+        sourceURI = Services.io.newURI(sourceURI);
         let uri;
         if (type == "resource") {
           // resources go about a slightly different way than everything else
-          let rph = ios.getProtocolHandler("resource").
+          let rph = Services.io.getProtocolHandler("resource").
                     QueryInterface(Ci.nsIResProtocolHandler);
           // this throws for packages that are not registered
           uri = rph.resolveURI(sourceURI);
         } else {
           // this throws for packages that are not registered
           uri = cr.convertChromeURL(sourceURI).spec;
         }
 

--- a/chrome/test/unit/test_resolve_uris.js
+++ b/chrome/test/unit/test_resolve_uris.js
@@ -8,27 +8,25 @@ if (typeof registerManifests === "undefi
   load("../unit/head_crtestutils.js");
 }
 
 var manifestFile = do_get_file("../unit/data/test_resolve_uris.manifest");
 
 var manifests = [ manifestFile ];
 registerManifests(manifests);
 
-var ios = Cc["@mozilla.org/network/io-service;1"].
-          getService(Ci.nsIIOService);
-
 function do_run_test() {
   let cr = Cc["@mozilla.org/chrome/chrome-registry;1"].
            getService(Ci.nsIChromeRegistry);
 
   // If we don't have libxul or e10s then we don't have process separation, so
   // we don't need to worry about checking for new chrome.
   var appInfo = Cc["@mozilla.org/xre/app-info;1"];
   if (!appInfo ||
+      // eslint-disable-next-line mozilla/use-services
       (appInfo.getService(Ci.nsIXULRuntime).processType ==
        Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT)) {
     cr.checkForNewChrome();
   }
 
   // See if our various things were able to register
   let registrationTypes = [
       "content",
@@ -53,26 +51,26 @@ function do_run_test() {
       case "skin":
         expectedURI += "foo.css";
         break;
       case "override":
         sourceURI = "chrome://good-package/content/override-me.xul";
         expectedURI += "override-me.xul";
         break;
       case "resource":
-        expectedURI = ios.newFileURI(manifestFile.parent).spec;
+        expectedURI = Services.io.newFileURI(manifestFile.parent).spec;
         sourceURI = "resource://foo/";
         break;
     }
     try {
-      sourceURI = ios.newURI(sourceURI);
+      sourceURI = Services.io.newURI(sourceURI);
       let uri;
       if (type == "resource") {
         // resources go about a slightly different way than everything else
-        let rph = ios.getProtocolHandler("resource").
+        let rph = Services.io.getProtocolHandler("resource").
             QueryInterface(Ci.nsIResProtocolHandler);
         uri = rph.resolveURI(sourceURI);
       } else {
         uri = cr.convertChromeURL(sourceURI).spec;
       }
 
       do_check_eq(expectedURI, uri);
     } catch (e) {