diff -r 000000000000 -r 6474c204b198 browser/metro/base/content/TopSites.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/metro/base/content/TopSites.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,158 @@
+// -*- Mode: js2; tab-width: 2; indent-tabs-mode: nil; js2-basic-offset: 2; js2-skip-preprocessor-directives: t; -*-
+/* 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';
+
+/**
+ * singleton to provide data-level functionality to the views
+ */
+let TopSites = {
+  prepareCache: function(aForce){
+    // front to the NewTabUtils' links cache
+    //  -ensure NewTabUtils.links links are pre-cached
+
+    // avoid re-fetching links data while a fetch is in flight
+    if (this._promisedCache && !aForce) {
+      return this._promisedCache;
+    }
+    let deferred = Promise.defer();
+    this._promisedCache = deferred.promise;
+
+    NewTabUtils.links.populateCache(function () {
+      deferred.resolve();
+      this._promisedCache = null;
+      this._sites = null;  // reset our sites cache so they are built anew
+      this._sitesDirty.clear();
+    }.bind(this), true);
+    return this._promisedCache;
+  },
+
+  _sites: null,
+  _sitesDirty: new Set(),
+  getSites: function() {
+    if (this._sites) {
+      return this._sites;
+    }
+
+    let links = NewTabUtils.links.getLinks();
+    let sites = links.map(function(aLink){
+      let site = new Site(aLink);
+      return site;
+    });
+
+    // reset state
+    this._sites = sites;
+    this._sitesDirty.clear();
+    return this._sites;
+  },
+
+  /**
+   * Get list of top site as in need of update/re-render
+   * @param aSite Optionally add Site arguments to be refreshed/updated
+   */
+  dirty: function() {
+    // add any arguments for more fine-grained updates rather than invalidating the whole collection
+    for (let i=0; i<arguments.length; i++) {
+      this._sitesDirty.add(arguments[i]);
+    }
+    return this._sitesDirty;
+  },
+
+  /**
+   * Cause update of top sites
+   */
+  update: function() {
+    NewTabUtils.allPages.update();
+    // then clear all the dirty flags
+    this._sitesDirty.clear();
+  },
+
+  /**
+   * Pin top site at a given index
+   * @param aSites array of sites to be pinned
+   * @param aSlotIndices indices corresponding to the site to be pinned
+   */
+  pinSites: function(aSites, aSlotIndices) {
+    if (aSites.length !== aSlotIndices.length)
+        throw new Error("TopSites.pinSites: Mismatched sites/indices arguments");
+
+    for (let i=0; i<aSites.length && i<aSlotIndices.length; i++){
+      let site = aSites[i],
+          idx = aSlotIndices[i];
+      if (!(site && site.url)) {
+        throw Cr.NS_ERROR_INVALID_ARG
+      }
+      // pinned state is a pref, using Storage apis therefore sync
+      NewTabUtils.pinnedLinks.pin(site, idx);
+      this.dirty(site);
+    }
+    this.update();
+  },
+
+  /**
+   * Unpin top sites
+   * @param aSites array of sites to be unpinned
+   */
+  unpinSites: function(aSites) {
+    for (let site of aSites) {
+      if (!(site && site.url)) {
+        throw Cr.NS_ERROR_INVALID_ARG
+      }
+      // pinned state is a pref, using Storage apis therefore sync
+      NewTabUtils.pinnedLinks.unpin(site);
+      this.dirty(site);
+    }
+    this.update();
+  },
+
+  /**
+   * Hide (block) top sites
+   * @param aSites array of sites to be unpinned
+   */
+  hideSites: function(aSites) {
+    for (let site of aSites) {
+      if (!(site && site.url)) {
+        throw Cr.NS_ERROR_INVALID_ARG
+      }
+
+      site._restorePinIndex = NewTabUtils.pinnedLinks._indexOfLink(site);
+      // blocked state is a pref, using Storage apis therefore sync
+      NewTabUtils.blockedLinks.block(site);
+    }
+    // clear out the cache, we'll fetch and re-render
+    this._sites = null;
+    this._sitesDirty.clear();
+    this.update();
+  },
+
+  /**
+   * Un-hide (restore) top sites
+   * @param aSites array of sites to be restored
+   */
+  restoreSites: function(aSites) {
+    for (let site of aSites) {
+      if (!(site && site.url)) {
+        throw Cr.NS_ERROR_INVALID_ARG
+      }
+      NewTabUtils.blockedLinks.unblock(site);
+      let pinIndex = site._restorePinIndex;
+
+      if (!isNaN(pinIndex) && pinIndex > -1) {
+        NewTabUtils.pinnedLinks.pin(site, pinIndex);
+      }
+    }
+    // clear out the cache, we'll fetch and re-render
+    this._sites = null;
+    this._sitesDirty.clear();
+    this.update();
+  },
+
+  _linkFromNode: function _linkFromNode(aNode) {
+    return {
+      url: aNode.getAttribute("value"),
+      title: aNode.getAttribute("label")
+    };
+  }
+};
+