diff -r 000000000000 -r 6474c204b198 toolkit/modules/DirectoryLinksProvider.jsm
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/modules/DirectoryLinksProvider.jsm	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,204 @@
+/* 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 = ["DirectoryLinksProvider"];
+
+const Ci = Components.interfaces;
+const Cc = Components.classes;
+const Cu = Components.utils;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+
+XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
+  "resource://gre/modules/NetUtil.jsm");
+
+/**
+ * Gets the currently selected locale for display.
+ * @return  the selected locale or "en-US" if none is selected
+ */
+function getLocale() {
+  let matchOS;
+  try {
+    matchOS = Services.prefs.getBoolPref(PREF_MATCH_OS_LOCALE);
+  }
+  catch (e) {}
+
+  if (matchOS) {
+    return Services.locale.getLocaleComponentForUserAgent();
+  }
+
+  try {
+    let locale = Services.prefs.getComplexValue(PREF_SELECTED_LOCALE,
+                                                Ci.nsIPrefLocalizedString);
+    if (locale) {
+      return locale.data;
+    }
+  }
+  catch (e) {}
+
+  try {
+    return Services.prefs.getCharPref(PREF_SELECTED_LOCALE);
+  }
+  catch (e) {}
+
+  return "en-US";
+}
+
+// The preference that tells whether to match the OS locale
+const PREF_MATCH_OS_LOCALE = "intl.locale.matchOS";
+
+// The preference that tells what locale the user selected
+const PREF_SELECTED_LOCALE = "general.useragent.locale";
+
+// The preference that tells where to obtain directory links
+const PREF_DIRECTORY_SOURCE = "browser.newtabpage.directorySource";
+
+// The frecency of a directory link
+const DIRECTORY_FRECENCY = 1000;
+
+const LINK_TYPES = Object.freeze([
+  "sponsored",
+  "affiliate",
+  "organic",
+]);
+
+/**
+ * Singleton that serves as the provider of directory links.
+ * Directory links are a hard-coded set of links shown if a user's link
+ * inventory is empty.
+ */
+let DirectoryLinksProvider = {
+
+  __linksURL: null,
+
+  _observers: [],
+
+  get _prefs() Object.freeze({
+    linksURL: PREF_DIRECTORY_SOURCE,
+    matchOSLocale: PREF_MATCH_OS_LOCALE,
+    prefSelectedLocale: PREF_SELECTED_LOCALE,
+  }),
+
+  get _linksURL() {
+    if (!this.__linksURL) {
+      try {
+        this.__linksURL = Services.prefs.getCharPref(this._prefs["linksURL"]);
+      }
+      catch (e) {
+        Cu.reportError("Error fetching directory links url from prefs: " + e);
+      }
+    }
+    return this.__linksURL;
+  },
+
+  get linkTypes() LINK_TYPES,
+
+  observe: function DirectoryLinksProvider_observe(aSubject, aTopic, aData) {
+    if (aTopic == "nsPref:changed") {
+      if (aData == this._prefs["linksURL"]) {
+        delete this.__linksURL;
+      }
+      this._callObservers("onManyLinksChanged");
+    }
+  },
+
+  _addPrefsObserver: function DirectoryLinksProvider_addObserver() {
+    for (let pref in this._prefs) {
+      let prefName = this._prefs[pref];
+      Services.prefs.addObserver(prefName, this, false);
+    }
+  },
+
+  _removePrefsObserver: function DirectoryLinksProvider_removeObserver() {
+    for (let pref in this._prefs) {
+      let prefName = this._prefs[pref];
+      Services.prefs.removeObserver(prefName, this);
+    }
+  },
+
+  /**
+   * Fetches the current set of directory links.
+   * @param aCallback a callback that is provided a set of links.
+   */
+  _fetchLinks: function DirectoryLinksProvider_fetchLinks(aCallback) {
+    try {
+      NetUtil.asyncFetch(this._linksURL, (aInputStream, aResult, aRequest) => {
+        let output;
+        if (Components.isSuccessCode(aResult)) {
+          try {
+            let json = NetUtil.readInputStreamToString(aInputStream,
+                                                       aInputStream.available(),
+                                                       {charset: "UTF-8"});
+            let locale = getLocale();
+            output = JSON.parse(json)[locale];
+          }
+          catch (e) {
+            Cu.reportError(e);
+          }
+        }
+        else {
+          Cu.reportError(new Error("the fetch of " + this._linksURL + "was unsuccessful"));
+        }
+        aCallback(output || []);
+      });
+    }
+    catch (e) {
+      Cu.reportError(e);
+      aCallback([]);
+    }
+  },
+
+  /**
+   * Gets the current set of directory links.
+   * @param aCallback The function that the array of links is passed to.
+   */
+  getLinks: function DirectoryLinksProvider_getLinks(aCallback) {
+    this._fetchLinks(rawLinks => {
+      // all directory links have a frecency of DIRECTORY_FRECENCY
+      aCallback(rawLinks.map((link, position) => {
+        link.frecency = DIRECTORY_FRECENCY;
+        link.lastVisitDate = rawLinks.length - position;
+        return link;
+      }));
+    });
+  },
+
+  init: function DirectoryLinksProvider_init() {
+    this._addPrefsObserver();
+  },
+
+  /**
+   * Return the object to its pre-init state
+   */
+  reset: function DirectoryLinksProvider_reset() {
+    delete this.__linksURL;
+    this._removePrefsObserver();
+    this._removeObservers();
+  },
+
+  addObserver: function DirectoryLinksProvider_addObserver(aObserver) {
+    this._observers.push(aObserver);
+  },
+
+  _callObservers: function DirectoryLinksProvider__callObservers(aMethodName, aArg) {
+    for (let obs of this._observers) {
+      if (typeof(obs[aMethodName]) == "function") {
+        try {
+          obs[aMethodName](this, aArg);
+        } catch (err) {
+          Cu.reportError(err);
+        }
+      }
+    }
+  },
+
+  _removeObservers: function() {
+    while (this._observers.length) {
+      this._observers.pop();
+    }
+  }
+};