diff -r 000000000000 -r 6474c204b198 browser/components/tabview/favicons.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/tabview/favicons.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,141 @@
+/* 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/. */
+
+let FavIcons = {
+  // Pref that controls whether to display site icons.
+  PREF_CHROME_SITE_ICONS: "browser.chrome.site_icons",
+
+  // Pref that controls whether to display fav icons.
+  PREF_CHROME_FAVICONS: "browser.chrome.favicons",
+
+  // Lazy getter for pref browser.chrome.site_icons.
+  get _prefSiteIcons() {
+    delete this._prefSiteIcons;
+    this._prefSiteIcons = Services.prefs.getBoolPref(this.PREF_CHROME_SITE_ICONS);
+  },
+
+  // Lazy getter for pref browser.chrome.favicons.
+  get _prefFavicons() {
+    delete this._prefFavicons;
+    this._prefFavicons = Services.prefs.getBoolPref(this.PREF_CHROME_FAVICONS);
+  },
+
+  get defaultFavicon() this._favIconService.defaultFavicon.spec,
+
+  init: function FavIcons_init() {
+    XPCOMUtils.defineLazyServiceGetter(this, "_favIconService",
+      "@mozilla.org/browser/favicon-service;1", "nsIFaviconService");
+
+    Services.prefs.addObserver(this.PREF_CHROME_SITE_ICONS, this, false);
+    Services.prefs.addObserver(this.PREF_CHROME_FAVICONS, this, false);
+  },
+
+  uninit: function FavIcons_uninit() {
+    Services.prefs.removeObserver(this.PREF_CHROME_SITE_ICONS, this);
+    Services.prefs.removeObserver(this.PREF_CHROME_FAVICONS, this);
+  },
+
+  observe: function FavIcons_observe(subject, topic, data) {
+    let value = Services.prefs.getBoolPref(data);
+
+    if (data == this.PREF_CHROME_SITE_ICONS)
+      this._prefSiteIcons = value;
+    else if (data == this.PREF_CHROME_FAVICONS)
+      this._prefFavicons = value;
+  },
+
+  // ----------
+  // Function: getFavIconUrlForTab
+  // Gets the "favicon link URI" for the given xul:tab, or null if unavailable.
+  getFavIconUrlForTab: function FavIcons_getFavIconUrlForTab(tab, callback) {
+    this._isImageDocument(tab, function (isImageDoc) {
+      if (isImageDoc) {
+        callback(tab.pinned ? tab.image : null);
+      } else {
+        this._getFavIconForNonImageDocument(tab, callback);
+      }
+    }.bind(this));
+  },
+
+  // ----------
+  // Function: _getFavIconForNonImageDocument
+  // Retrieves the favicon for a tab containing a non-image document.
+  _getFavIconForNonImageDocument:
+    function FavIcons_getFavIconForNonImageDocument(tab, callback) {
+
+    if (tab.image)
+      this._getFavIconFromTabImage(tab, callback);
+    else if (this._shouldLoadFavIcon(tab))
+      this._getFavIconForHttpDocument(tab, callback);
+    else
+      callback(null);
+  },
+
+  // ----------
+  // Function: _getFavIconFromTabImage
+  // Retrieves the favicon for tab with a tab image.
+  _getFavIconFromTabImage:
+    function FavIcons_getFavIconFromTabImage(tab, callback) {
+
+    let tabImage = gBrowser.getIcon(tab);
+
+    // If the tab image's url starts with http(s), fetch icon from favicon
+    // service via the moz-anno protocol.
+    if (/^https?:/.test(tabImage)) {
+      let tabImageURI = gWindow.makeURI(tabImage);
+      tabImage = this._favIconService.getFaviconLinkForIcon(tabImageURI).spec;
+    }
+
+    callback(tabImage);
+  },
+
+  // ----------
+  // Function: _getFavIconForHttpDocument
+  // Retrieves the favicon for tab containg a http(s) document.
+  _getFavIconForHttpDocument:
+    function FavIcons_getFavIconForHttpDocument(tab, callback) {
+
+    let {currentURI} = tab.linkedBrowser;
+    this._favIconService.getFaviconURLForPage(currentURI, function (uri) {
+      if (uri) {
+        callback(this._favIconService.getFaviconLinkForIcon(uri).spec);
+      } else {
+        callback(this.defaultFavicon);
+      }
+    }.bind(this));
+  },
+
+  // ----------
+  // Function: _isImageDocument
+  // Checks whether an image is loaded into the given tab.
+  _isImageDocument: function UI__isImageDocument(tab, callback) {
+    let mm = tab.linkedBrowser.messageManager;
+    let message = "Panorama:isImageDocument";
+
+    mm.addMessageListener(message, function onMessage(cx) {
+      mm.removeMessageListener(cx.name, onMessage);
+      callback(cx.json.isImageDocument);
+    });
+
+    mm.sendAsyncMessage(message);
+  },
+
+  // ----------
+  // Function: _shouldLoadFavIcon
+  // Checks whether fav icon should be loaded for a given tab.
+  _shouldLoadFavIcon: function FavIcons_shouldLoadFavIcon(tab) {
+    // No need to load a favicon if the user doesn't want site or favicons.
+    if (!this._prefSiteIcons || !this._prefFavicons)
+      return false;
+
+    let uri = tab.linkedBrowser.currentURI;
+
+    // Stop here if we don't have a valid nsIURI.
+    if (!uri || !(uri instanceof Ci.nsIURI))
+      return false;
+
+    // Load favicons for http(s) pages only.
+    return uri.schemeIs("http") || uri.schemeIs("https");
+  }
+};