diff --git a/mobile/android/chrome/content/aboutAddons.js b/mobile/android/chrome/content/aboutAddons.js
index c2dd0d641399..02081153173b 100644
--- a/mobile/android/chrome/content/aboutAddons.js
+++ b/mobile/android/chrome/content/aboutAddons.js
@@ -25,9 +25,7 @@ var gStringBundle = Services.strings.createBundle(
 );
 
 XPCOMUtils.defineLazyGetter(window, "gChromeWin", function() {
-  return window.docShell.rootTreeItem.domWindow.QueryInterface(
-    Ci.nsIDOMChromeWindow
-  );
+  return window.docShell.rootTreeItem.domWindow;
 });
 ChromeUtils.defineModuleGetter(
   window,
diff --git a/mobile/android/chrome/content/aboutLogins.js b/mobile/android/chrome/content/aboutLogins.js
index e7eae6a91265..f78acc3e582e 100644
--- a/mobile/android/chrome/content/aboutLogins.js
+++ b/mobile/android/chrome/content/aboutLogins.js
@@ -11,8 +11,10 @@ const { XPCOMUtils } = ChromeUtils.import(
 );
 const { Accounts } = ChromeUtils.import("resource://gre/modules/Accounts.jsm");
 
-XPCOMUtils.defineLazyGetter(window, "gChromeWin", () =>
-  window.docShell.rootTreeItem.domWindow.QueryInterface(Ci.nsIDOMChromeWindow)
+XPCOMUtils.defineLazyGetter(
+  window,
+  "gChromeWin",
+  () => window.docShell.rootTreeItem.domWindow
 );
 
 ChromeUtils.defineModuleGetter(
diff --git a/mobile/android/chrome/content/aboutPrivateBrowsing.js b/mobile/android/chrome/content/aboutPrivateBrowsing.js
index 13007b1b5e4a..ab0ee11c854a 100644
--- a/mobile/android/chrome/content/aboutPrivateBrowsing.js
+++ b/mobile/android/chrome/content/aboutPrivateBrowsing.js
@@ -12,8 +12,10 @@ const { PrivateBrowsingUtils } = ChromeUtils.import(
   "resource://gre/modules/PrivateBrowsingUtils.jsm"
 );
 
-XPCOMUtils.defineLazyGetter(window, "gChromeWin", () =>
-  window.docShell.rootTreeItem.domWindow.QueryInterface(Ci.nsIDOMChromeWindow)
+XPCOMUtils.defineLazyGetter(
+  window,
+  "gChromeWin",
+  () => window.docShell.rootTreeItem.domWindow
 );
 
 document.addEventListener("DOMContentLoaded", function() {
diff --git a/mobile/android/components/ContentPermissionPrompt.js b/mobile/android/components/ContentPermissionPrompt.js
index d5e7673c5d83..8b23fce9f19f 100644
--- a/mobile/android/components/ContentPermissionPrompt.js
+++ b/mobile/android/components/ContentPermissionPrompt.js
@@ -61,10 +61,7 @@ ContentPermissionPrompt.prototype = {
   },
 
   getChromeWindow: function getChromeWindow(aWindow) {
-    let chromeWin = aWindow.docShell.rootTreeItem.domWindow.QueryInterface(
-      Ci.nsIDOMChromeWindow
-    );
-    return chromeWin;
+    return aWindow.docShell.rootTreeItem.domWindow;
   },
 
   getChromeForRequest: function getChromeForRequest(request) {
diff --git a/mobile/android/modules/ActionBarHandler.jsm b/mobile/android/modules/ActionBarHandler.jsm
index 7d57b822f392..3a77696f728b 100644
--- a/mobile/android/modules/ActionBarHandler.jsm
+++ b/mobile/android/modules/ActionBarHandler.jsm
@@ -587,8 +587,7 @@ var ActionBarHandler = {
         if (chrome.BrowserApp && chrome.BrowserApp.loadURI) {
           chrome.BrowserApp.loadURI(uri);
         } else {
-          let bwin = chrome.QueryInterface(Ci.nsIDOMChromeWindow)
-            .browserDOMWindow;
+          let bwin = chrome.browserDOMWindow;
           if (bwin) {
             bwin.openURI(
               Services.io.newURI(uri),
@@ -647,8 +646,7 @@ var ActionBarHandler = {
             isPrivate: isPrivate,
           });
         } else {
-          let bwin = chrome.QueryInterface(Ci.nsIDOMChromeWindow)
-            .browserDOMWindow;
+          let bwin = chrome.browserDOMWindow;
           if (bwin) {
             bwin.openURI(
               searchSubmission.uri,
diff --git a/mobile/android/modules/WebrtcUI.jsm b/mobile/android/modules/WebrtcUI.jsm
index d65af31e99f5..a05746ff2ef7 100644
--- a/mobile/android/modules/WebrtcUI.jsm
+++ b/mobile/android/modules/WebrtcUI.jsm
@@ -365,10 +365,7 @@ var WebrtcUI = {
   },
 
   getChromeWindow: function getChromeWindow(aWindow) {
-    let chromeWin = aWindow.docShell.rootTreeItem.domWindow.QueryInterface(
-      Ci.nsIDOMChromeWindow
-    );
-    return chromeWin;
+    return aWindow.docShell.rootTreeItem.domWindow;
   },
 
   prompt: function prompt(
diff --git a/testing/specialpowers/content/SpecialPowersAPI.jsm b/testing/specialpowers/content/SpecialPowersAPI.jsm
index 8d388ae18c8c..fd93bdd4615e 100644
--- a/testing/specialpowers/content/SpecialPowersAPI.jsm
+++ b/testing/specialpowers/content/SpecialPowersAPI.jsm
@@ -1036,9 +1036,7 @@ class SpecialPowersAPI extends JSWindowActorChild {
   // XXX: these APIs really ought to be removed, they're not e10s-safe.
   // (also they're pretty Firefox-specific)
   _getTopChromeWindow(window) {
-    return window.docShell.rootTreeItem.domWindow.QueryInterface(
-      Ci.nsIDOMChromeWindow
-    );
+    return window.docShell.rootTreeItem.domWindow;
   }
   _getAutoCompletePopup(window) {
     return this._getTopChromeWindow(window).document.getElementById(