diff -r 000000000000 -r 6474c204b198 toolkit/modules/BrowserUtils.jsm
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/modules/BrowserUtils.jsm	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,115 @@
+/* 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";
+
+this.EXPORTED_SYMBOLS = [ "BrowserUtils" ];
+
+const {interfaces: Ci, utils: Cu, classes: Cc} = Components;
+
+Cu.import("resource://gre/modules/Services.jsm");
+
+this.BrowserUtils = {
+
+  /**
+   * urlSecurityCheck: JavaScript wrapper for checkLoadURIWithPrincipal
+   * and checkLoadURIStrWithPrincipal.
+   * If |aPrincipal| is not allowed to link to |aURL|, this function throws with
+   * an error message.
+   *
+   * @param aURL
+   *        The URL a page has linked to. This could be passed either as a string
+   *        or as a nsIURI object.
+   * @param aPrincipal
+   *        The principal of the document from which aURL came.
+   * @param aFlags
+   *        Flags to be passed to checkLoadURIStr. If undefined,
+   *        nsIScriptSecurityManager.STANDARD will be passed.
+   */
+  urlSecurityCheck: function(aURL, aPrincipal, aFlags) {
+    var secMan = Services.scriptSecurityManager;
+    if (aFlags === undefined) {
+      aFlags = secMan.STANDARD;
+    }
+
+    try {
+      if (aURL instanceof Ci.nsIURI)
+        secMan.checkLoadURIWithPrincipal(aPrincipal, aURL, aFlags);
+      else
+        secMan.checkLoadURIStrWithPrincipal(aPrincipal, aURL, aFlags);
+    } catch (e) {
+      let principalStr = "";
+      try {
+        principalStr = " from " + aPrincipal.URI.spec;
+      }
+      catch(e2) { }
+
+      throw "Load of " + aURL + principalStr + " denied.";
+    }
+  },
+
+  /**
+   * Constructs a new URI, using nsIIOService.
+   * @param aURL The URI spec.
+   * @param aOriginCharset The charset of the URI.
+   * @param aBaseURI Base URI to resolve aURL, or null.
+   * @return an nsIURI object based on aURL.
+   */
+  makeURI: function(aURL, aOriginCharset, aBaseURI) {
+    return Services.io.newURI(aURL, aOriginCharset, aBaseURI);
+  },
+
+  makeFileURI: function(aFile) {
+    return Services.io.newFileURI(aFile);
+  },
+
+  /**
+   * Return the current focus element and window. If the current focus
+   * is in a content process, then this function returns CPOWs
+   * (cross-process object wrappers) that refer to the focused
+   * items. Note that calling this function synchronously contacts the
+   * content process, which may block for a long time.
+   *
+   * @param document The document in question.
+   * @return [focusedElement, focusedWindow]
+   */
+  getFocusSync: function(document) {
+    let elt = document.commandDispatcher.focusedElement;
+    var window = document.commandDispatcher.focusedWindow;
+
+    const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+    if (elt instanceof window.XULElement &&
+        elt.localName == "browser" &&
+        elt.namespaceURI == XUL_NS &&
+        elt.getAttribute("remote")) {
+      [elt, window] = elt.syncHandler.getFocusedElementAndWindow();
+    }
+
+    return [elt, window];
+  },
+
+  /**
+   * For a given DOM element, returns its position in "screen"
+   * coordinates. In a content process, the coordinates returned will
+   * be relative to the left/top of the tab. In the chrome process,
+   * the coordinates are relative to the user's screen.
+   */
+  getElementBoundingScreenRect: function(aElement) {
+    let rect = aElement.getBoundingClientRect();
+    let window = aElement.ownerDocument.defaultView;
+
+    // We need to compensate for any iframes that might shift things
+    // over. We also need to compensate for zooming.
+    let fullZoom = window.getInterface(Ci.nsIDOMWindowUtils).fullZoom;
+    rect = {
+      left: (rect.left + window.mozInnerScreenX) * fullZoom,
+      top: (rect.top + window.mozInnerScreenY) * fullZoom,
+      width: rect.width * fullZoom,
+      height: rect.height * fullZoom
+    };
+
+    return rect;
+  },
+
+};