diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 808bf477a774..4ceac25babdf 100644
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -5311,7 +5311,8 @@ var XULBrowserWindow = {
 
     if (aWebProgress.isTopLevel) {
       if (
-        (location == "about:blank" && checkEmptyPageOrigin()) ||
+        (location == "about:blank" &&
+          BrowserUtils.checkEmptyPageOrigin(gBrowser.selectedBrowser)) ||
         location == ""
       ) {
         // Second condition is for new tabs, otherwise
@@ -8240,68 +8241,6 @@ function undoCloseWindow(aIndex) {
   return window;
 }
 
-/**
- * Check whether a page can be considered as 'empty', that its URI
- * reflects its origin, and that if it's loaded in a tab, that tab
- * could be considered 'empty' (e.g. like the result of opening
- * a 'blank' new tab).
- *
- * We have to do more than just check the URI, because especially
- * for things like about:blank, it is possible that the opener or
- * some other page has control over the contents of the page.
- *
- * @param browser {Browser}
- *        The browser whose page we're checking (the selected browser
- *        in this window if omitted).
- * @param uri {nsIURI}
- *        The URI against which we're checking (the browser's currentURI
- *        if omitted).
- *
- * @return false if the page was opened by or is controlled by arbitrary web
- *         content, unless that content corresponds with the URI.
- *         true if the page is blank and controlled by a principal matching
- *         that URI (or the system principal if the principal has no URI)
- */
-function checkEmptyPageOrigin(
-  browser = gBrowser.selectedBrowser,
-  uri = browser.currentURI
-) {
-  // If another page opened this page with e.g. window.open, this page might
-  // be controlled by its opener - return false.
-  if (browser.hasContentOpener) {
-    return false;
-  }
-  let contentPrincipal = browser.contentPrincipal;
-  // Not all principals have URIs...
-  if (contentPrincipal.URI) {
-    // There are two special-cases involving about:blank. One is where
-    // the user has manually loaded it and it got created with a null
-    // principal. The other involves the case where we load
-    // some other empty page in a browser and the current page is the
-    // initial about:blank page (which has that as its principal, not
-    // just URI in which case it could be web-based). Especially in
-    // e10s, we need to tackle that case specifically to avoid race
-    // conditions when updating the URL bar.
-    //
-    // Note that we check the documentURI here, since the currentURI on
-    // the browser might have been set by SessionStore in order to
-    // support switch-to-tab without having actually loaded the content
-    // yet.
-    let uriToCheck = browser.documentURI || uri;
-    if (
-      (uriToCheck.spec == "about:blank" && contentPrincipal.isNullPrincipal) ||
-      contentPrincipal.URI.spec == "about:blank"
-    ) {
-      return true;
-    }
-    return contentPrincipal.URI.equals(uri);
-  }
-  // ... so for those that don't have them, enforce that the page has the
-  // system principal (this matches e.g. on about:newtab).
-
-  return contentPrincipal.isSystemPrincipal;
-}
-
 function ReportFalseDeceptiveSite() {
   let contextsToVisit = [gBrowser.selectedBrowser.browsingContext];
   while (contextsToVisit.length) {
diff --git a/browser/base/content/tabbrowser-tab.js b/browser/base/content/tabbrowser-tab.js
index bed02186d96d..35df9e1595bf 100644
--- a/browser/base/content/tabbrowser-tab.js
+++ b/browser/base/content/tabbrowser-tab.js
@@ -217,7 +217,7 @@
         return false;
       }
 
-      if (!checkEmptyPageOrigin(browser)) {
+      if (!BrowserUtils.checkEmptyPageOrigin(browser)) {
         return false;
       }
 
diff --git a/browser/components/urlbar/UrlbarInput.jsm b/browser/components/urlbar/UrlbarInput.jsm
index db440eac178b..8aff7f7e38ec 100644
--- a/browser/components/urlbar/UrlbarInput.jsm
+++ b/browser/components/urlbar/UrlbarInput.jsm
@@ -278,7 +278,7 @@ class UrlbarInput {
       // only if there's no opener (bug 370555).
       if (
         this.window.isInitialPage(uri) &&
-        this.window.checkEmptyPageOrigin(
+        BrowserUtils.checkEmptyPageOrigin(
           this.window.gBrowser.selectedBrowser,
           uri
         )
@@ -297,7 +297,7 @@ class UrlbarInput {
         !this.window.isBlankPageURL(uri.spec) || uri.schemeIs("moz-extension");
     } else if (
       this.window.isInitialPage(value) &&
-      this.window.checkEmptyPageOrigin(this.window.gBrowser.selectedBrowser)
+      BrowserUtils.checkEmptyPageOrigin(this.window.gBrowser.selectedBrowser)
     ) {
       value = "";
       valid = true;
diff --git a/toolkit/modules/BrowserUtils.jsm b/toolkit/modules/BrowserUtils.jsm
index fe6c376c6db3..aa5791ac526f 100644
--- a/toolkit/modules/BrowserUtils.jsm
+++ b/toolkit/modules/BrowserUtils.jsm
@@ -55,6 +55,64 @@ var BrowserUtils = {
     return undefined;
   },
 
+  /**
+   * Check whether a page can be considered as 'empty', that its URI
+   * reflects its origin, and that if it's loaded in a tab, that tab
+   * could be considered 'empty' (e.g. like the result of opening
+   * a 'blank' new tab).
+   *
+   * We have to do more than just check the URI, because especially
+   * for things like about:blank, it is possible that the opener or
+   * some other page has control over the contents of the page.
+   *
+   * @param {Browser} browser
+   *        The browser whose page we're checking.
+   * @param {nsIURI} [uri]
+   *        The URI against which we're checking (the browser's currentURI
+   *        if omitted).
+   *
+   * @return {boolean} false if the page was opened by or is controlled by
+   *         arbitrary web content, unless that content corresponds with the URI.
+   *         true if the page is blank and controlled by a principal matching
+   *         that URI (or the system principal if the principal has no URI)
+   */
+  checkEmptyPageOrigin(browser, uri = browser.currentURI) {
+    // If another page opened this page with e.g. window.open, this page might
+    // be controlled by its opener.
+    if (browser.hasContentOpener) {
+      return false;
+    }
+    let contentPrincipal = browser.contentPrincipal;
+    // Not all principals have URIs...
+    if (contentPrincipal.URI) {
+      // There are two special-cases involving about:blank. One is where
+      // the user has manually loaded it and it got created with a null
+      // principal. The other involves the case where we load
+      // some other empty page in a browser and the current page is the
+      // initial about:blank page (which has that as its principal, not
+      // just URI in which case it could be web-based). Especially in
+      // e10s, we need to tackle that case specifically to avoid race
+      // conditions when updating the URL bar.
+      //
+      // Note that we check the documentURI here, since the currentURI on
+      // the browser might have been set by SessionStore in order to
+      // support switch-to-tab without having actually loaded the content
+      // yet.
+      let uriToCheck = browser.documentURI || uri;
+      if (
+        (uriToCheck.spec == "about:blank" &&
+          contentPrincipal.isNullPrincipal) ||
+        contentPrincipal.URI.spec == "about:blank"
+      ) {
+        return true;
+      }
+      return contentPrincipal.URI.equals(uri);
+    }
+    // ... so for those that don't have them, enforce that the page has the
+    // system principal (this matches e.g. on about:newtab).
+    return contentPrincipal.isSystemPrincipal;
+  },
+
   /**
    * urlSecurityCheck: JavaScript wrapper for checkLoadURIWithPrincipal
    * and checkLoadURIStrWithPrincipal.