Adding upstream version 127.0.upstream/127.0

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 5626 insertions, 0 deletions

diff --git a/browser/components/topsites/TopSites.sys.mjs b/browser/components/topsites/TopSites.sys.mjs
new file mode 100644
index 0000000000..736a079f34
--- /dev/null
+++ b/browser/components/topsites/TopSites.sys.mjs
@@ -0,0 +1,2039 @@
+/* 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/. */
+
+import {
+  actionCreators as ac,
+  actionTypes as at,
+} from "resource://activity-stream/common/Actions.mjs";
+import { TippyTopProvider } from "resource://activity-stream/lib/TippyTopProvider.sys.mjs";
+import {
+  insertPinned,
+  TOP_SITES_MAX_SITES_PER_ROW,
+} from "resource://activity-stream/common/Reducers.sys.mjs";
+import { Dedupe } from "resource://activity-stream/common/Dedupe.sys.mjs";
+import { shortURL } from "resource://activity-stream/lib/ShortURL.sys.mjs";
+import { getDefaultOptions } from "resource://activity-stream/lib/ActivityStreamStorage.sys.mjs";
+
+import {
+  CUSTOM_SEARCH_SHORTCUTS,
+  SEARCH_SHORTCUTS_EXPERIMENT,
+  SEARCH_SHORTCUTS_SEARCH_ENGINES_PREF,
+  SEARCH_SHORTCUTS_HAVE_PINNED_PREF,
+  checkHasSearchEngine,
+  getSearchProvider,
+  getSearchFormURL,
+} from "resource://activity-stream/lib/SearchShortcuts.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  FilterAdult: "resource://activity-stream/lib/FilterAdult.sys.mjs",
+  LinksCache: "resource://activity-stream/lib/LinksCache.sys.mjs",
+  NewTabUtils: "resource://gre/modules/NewTabUtils.sys.mjs",
+  NimbusFeatures: "resource://nimbus/ExperimentAPI.sys.mjs",
+  PageThumbs: "resource://gre/modules/PageThumbs.sys.mjs",
+  Region: "resource://gre/modules/Region.sys.mjs",
+  RemoteSettings: "resource://services-settings/remote-settings.sys.mjs",
+  Sampling: "resource://gre/modules/components-utils/Sampling.sys.mjs",
+  Screenshots: "resource://activity-stream/lib/Screenshots.sys.mjs",
+});
+
+ChromeUtils.defineLazyGetter(lazy, "log", () => {
+  const { Logger } = ChromeUtils.importESModule(
+    "resource://messaging-system/lib/Logger.sys.mjs"
+  );
+  return new Logger("TopSites");
+});
+
+// `contextId` is a unique identifier used by Contextual Services
+const CONTEXT_ID_PREF = "browser.contextual-services.contextId";
+ChromeUtils.defineLazyGetter(lazy, "contextId", () => {
+  let _contextId = Services.prefs.getStringPref(CONTEXT_ID_PREF, null);
+  if (!_contextId) {
+    _contextId = String(Services.uuid.generateUUID());
+    Services.prefs.setStringPref(CONTEXT_ID_PREF, _contextId);
+  }
+  return _contextId;
+});
+
+const DEFAULT_SITES_PREF = "default.sites";
+const SHOWN_ON_NEWTAB_PREF = "feeds.topsites";
+export const DEFAULT_TOP_SITES = [];
+const FRECENCY_THRESHOLD = 100 + 1; // 1 visit (skip first-run/one-time pages)
+const MIN_FAVICON_SIZE = 96;
+const CACHED_LINK_PROPS_TO_MIGRATE = ["screenshot", "customScreenshot"];
+const PINNED_FAVICON_PROPS_TO_MIGRATE = [
+  "favicon",
+  "faviconRef",
+  "faviconSize",
+];
+const SECTION_ID = "topsites";
+const ROWS_PREF = "topSitesRows";
+const SHOW_SPONSORED_PREF = "showSponsoredTopSites";
+// The default total number of sponsored top sites to fetch from Contile
+// and Pocket.
+const MAX_NUM_SPONSORED = 2;
+// Nimbus variable for the total number of sponsored top sites including
+// both Contile and Pocket sources.
+// The default will be `MAX_NUM_SPONSORED` if this variable is unspecified.
+const NIMBUS_VARIABLE_MAX_SPONSORED = "topSitesMaxSponsored";
+// Nimbus variable to allow more than two sponsored tiles from Contile to be
+//considered for Top Sites.
+const NIMBUS_VARIABLE_ADDITIONAL_TILES =
+  "topSitesUseAdditionalTilesFromContile";
+// Nimbus variable to enable the SOV feature for sponsored tiles.
+const NIMBUS_VARIABLE_CONTILE_SOV_ENABLED = "topSitesContileSovEnabled";
+// Nimbu variable for the total number of sponsor topsite that come from Contile
+// The default will be `CONTILE_MAX_NUM_SPONSORED` if variable is unspecified.
+const NIMBUS_VARIABLE_CONTILE_MAX_NUM_SPONSORED = "topSitesContileMaxSponsored";
+
+// Search experiment stuff
+const FILTER_DEFAULT_SEARCH_PREF = "improvesearch.noDefaultSearchTile";
+const SEARCH_FILTERS = [
+  "google",
+  "search.yahoo",
+  "yahoo",
+  "bing",
+  "ask",
+  "duckduckgo",
+];
+
+const REMOTE_SETTING_DEFAULTS_PREF = "browser.topsites.useRemoteSetting";
+const DEFAULT_SITES_OVERRIDE_PREF =
+  "browser.newtabpage.activity-stream.default.sites";
+const DEFAULT_SITES_EXPERIMENTS_PREF_BRANCH = "browser.topsites.experiment.";
+
+// Mozilla Tiles Service (Contile) prefs
+// Nimbus variable for the Contile integration. It falls back to the pref:
+// `browser.topsites.contile.enabled`.
+const NIMBUS_VARIABLE_CONTILE_ENABLED = "topSitesContileEnabled";
+const NIMBUS_VARIABLE_CONTILE_POSITIONS = "contileTopsitesPositions";
+const CONTILE_ENDPOINT_PREF = "browser.topsites.contile.endpoint";
+const CONTILE_UPDATE_INTERVAL = 15 * 60 * 1000; // 15 minutes
+// The maximum number of sponsored top sites to fetch from Contile.
+const CONTILE_MAX_NUM_SPONSORED = 2;
+const TOP_SITES_BLOCKED_SPONSORS_PREF = "browser.topsites.blockedSponsors";
+const CONTILE_CACHE_PREF = "browser.topsites.contile.cachedTiles";
+const CONTILE_CACHE_VALID_FOR_PREF = "browser.topsites.contile.cacheValidFor";
+const CONTILE_CACHE_LAST_FETCH_PREF = "browser.topsites.contile.lastFetch";
+
+// Partners of sponsored tiles.
+const SPONSORED_TILE_PARTNER_AMP = "amp";
+const SPONSORED_TILE_PARTNER_MOZ_SALES = "moz-sales";
+const SPONSORED_TILE_PARTNERS = new Set([
+  SPONSORED_TILE_PARTNER_AMP,
+  SPONSORED_TILE_PARTNER_MOZ_SALES,
+]);
+
+const DISPLAY_FAIL_REASON_OVERSOLD = "oversold";
+const DISPLAY_FAIL_REASON_DISMISSED = "dismissed";
+const DISPLAY_FAIL_REASON_UNRESOLVED = "unresolved";
+
+function getShortURLForCurrentSearch() {
+  const url = shortURL({ url: Services.search.defaultEngine.searchForm });
+  return url;
+}
+
+class TopSitesTelemetry {
+  constructor() {
+    this.allSponsoredTiles = {};
+    this.sponsoredTilesConfigured = 0;
+  }
+
+  _tileProviderForTiles(tiles) {
+    // Assumption: the list of tiles is from a single provider
+    return tiles && tiles.length ? this._tileProvider(tiles[0]) : null;
+  }
+
+  _tileProvider(tile) {
+    return tile.partner || SPONSORED_TILE_PARTNER_AMP;
+  }
+
+  _buildPropertyKey(tile) {
+    let provider = this._tileProvider(tile);
+    return provider + shortURL(tile);
+  }
+
+  // Returns an array of strings indicating the property name (based on the
+  // provider and brand) of tiles that have been filtered e.g. ["moz-salesbrand1"]
+  // currentTiles: The list of tiles remaining and may be displayed in new tab.
+  // this.allSponsoredTiles: The original list of tiles set via setTiles prior to any filtering
+  // The returned list indicated the difference between these two lists (excluding any previously filtered tiles).
+  _getFilteredTiles(currentTiles) {
+    let notPreviouslyFilteredTiles = Object.assign(
+      {},
+      ...Object.entries(this.allSponsoredTiles)
+        .filter(
+          ([, v]) =>
+            v.display_fail_reason === null ||
+            v.display_fail_reason === undefined
+        )
+        .map(([k, v]) => ({ [k]: v }))
+    );
+
+    // Get the property names of the newly filtered list.
+    let remainingTiles = currentTiles.map(el => {
+      return this._buildPropertyKey(el);
+    });
+
+    // Get the property names of the tiles that were filtered.
+    let tilesToUpdate = Object.keys(notPreviouslyFilteredTiles).filter(
+      element => !remainingTiles.includes(element)
+    );
+    return tilesToUpdate;
+  }
+
+  setSponsoredTilesConfigured() {
+    const maxSponsored =
+      lazy.NimbusFeatures.pocketNewtab.getVariable(
+        NIMBUS_VARIABLE_MAX_SPONSORED
+      ) ?? MAX_NUM_SPONSORED;
+
+    this.sponsoredTilesConfigured = maxSponsored;
+    Glean.topsites.sponsoredTilesConfigured.set(maxSponsored);
+  }
+
+  clearTilesForProvider(provider) {
+    Object.entries(this.allSponsoredTiles)
+      .filter(([k]) => k.startsWith(provider))
+      .map(([k]) => delete this.allSponsoredTiles[k]);
+  }
+
+  _getAdvertiser(tile) {
+    let label = tile.label || null;
+    let title = tile.title || null;
+
+    return label ?? title ?? shortURL(tile);
+  }
+
+  setTiles(tiles) {
+    // Assumption: the list of tiles is from a single provider,
+    // should be called once per tile source.
+    if (tiles && tiles.length) {
+      let tile_provider = this._tileProviderForTiles(tiles);
+      this.clearTilesForProvider(tile_provider);
+
+      for (let sponsoredTile of tiles) {
+        this.allSponsoredTiles[this._buildPropertyKey(sponsoredTile)] = {
+          advertiser: this._getAdvertiser(sponsoredTile).toLowerCase(),
+          provider: tile_provider,
+          display_position: null,
+          display_fail_reason: null,
+        };
+      }
+    }
+  }
+
+  _setDisplayFailReason(filteredTiles, reason) {
+    for (let tile of filteredTiles) {
+      if (tile in this.allSponsoredTiles) {
+        let tileToUpdate = this.allSponsoredTiles[tile];
+        tileToUpdate.display_position = null;
+        tileToUpdate.display_fail_reason = reason;
+      }
+    }
+  }
+
+  determineFilteredTilesAndSetToOversold(nonOversoldTiles) {
+    let filteredTiles = this._getFilteredTiles(nonOversoldTiles);
+    this._setDisplayFailReason(filteredTiles, DISPLAY_FAIL_REASON_OVERSOLD);
+  }
+
+  determineFilteredTilesAndSetToDismissed(nonDismissedTiles) {
+    let filteredTiles = this._getFilteredTiles(nonDismissedTiles);
+    this._setDisplayFailReason(filteredTiles, DISPLAY_FAIL_REASON_DISMISSED);
+  }
+
+  _setTilePositions(currentTiles) {
+    // This function performs many loops over a small dataset.  The size of
+    // dataset is limited by the number of sponsored tiles displayed on
+    // the newtab instance.
+    if (this.allSponsoredTiles) {
+      let tilePositionsAssigned = [];
+      // processing the currentTiles parameter, assigns a position to the
+      // corresponding property in this.allSponsoredTiles
+      currentTiles.forEach(item => {
+        let tile = this.allSponsoredTiles[this._buildPropertyKey(item)];
+        if (
+          tile &&
+          (tile.display_fail_reason === undefined ||
+            tile.display_fail_reason === null)
+        ) {
+          tile.display_position = item.sponsored_position;
+          // Track assigned tile slots.
+          tilePositionsAssigned.push(item.sponsored_position);
+        }
+      });
+
+      // Need to check if any objects in this.allSponsoredTiles do not
+      // have either a display_fail_reason or a display_position set.
+      // This can happen if the tiles list was updated before the
+      // metric is written to Glean.
+      // See https://bugzilla.mozilla.org/show_bug.cgi?id=1877197
+      let tilesMissingPosition = [];
+      Object.keys(this.allSponsoredTiles).forEach(property => {
+        let tile = this.allSponsoredTiles[property];
+        if (!tile.display_fail_reason && !tile.display_position) {
+          tilesMissingPosition.push(property);
+        }
+      });
+
+      if (tilesMissingPosition.length) {
+        // Determine if any available slots exist based on max number of tiles
+        // and the list of tiles already used and assign to a tile with missing
+        // value.
+        for (let i = 1; i <= this.sponsoredTilesConfigured; i++) {
+          if (!tilePositionsAssigned.includes(i)) {
+            let tileProperty = tilesMissingPosition.shift();
+            this.allSponsoredTiles[tileProperty].display_position = i;
+          }
+        }
+      }
+
+      // At this point we might still have a few unresolved states.  These
+      // rows will be tagged with a display_fail_reason `unresolved`.
+      this._detectErrorConditionAndSetUnresolved();
+    }
+  }
+
+  // Checks the data for inconsistent state and updates the display_fail_reason
+  _detectErrorConditionAndSetUnresolved() {
+    Object.keys(this.allSponsoredTiles).forEach(property => {
+      let tile = this.allSponsoredTiles[property];
+      if (
+        (!tile.display_fail_reason && !tile.display_position) ||
+        (tile.display_fail_reason && tile.display_position)
+      ) {
+        tile.display_position = null;
+        tile.display_fail_reason = DISPLAY_FAIL_REASON_UNRESOLVED;
+      }
+    });
+  }
+
+  finalizeNewtabPingFields(currentTiles) {
+    this._setTilePositions(currentTiles);
+    Glean.topsites.sponsoredTilesReceived.set(
+      JSON.stringify({
+        sponsoredTilesReceived: Object.values(this.allSponsoredTiles),
+      })
+    );
+  }
+}
+
+export class ContileIntegration {
+  constructor(topSitesFeed) {
+    this._topSitesFeed = topSitesFeed;
+    this._lastPeriodicUpdate = 0;
+    this._sites = [];
+    // The Share-of-Voice object managed by Shepherd and sent via Contile.
+    this._sov = null;
+  }
+
+  get sites() {
+    return this._sites;
+  }
+
+  get sov() {
+    return this._sov;
+  }
+
+  periodicUpdate() {
+    let now = Date.now();
+    if (now - this._lastPeriodicUpdate >= CONTILE_UPDATE_INTERVAL) {
+      this._lastPeriodicUpdate = now;
+      this.refresh();
+    }
+  }
+
+  async refresh() {
+    let updateDefaultSites = await this._fetchSites();
+    await this._topSitesFeed.allocatePositions();
+    if (updateDefaultSites) {
+      this._topSitesFeed._readDefaults();
+    }
+  }
+
+  /**
+   * Clear Contile Cache Prefs.
+   */
+  _resetContileCachePrefs() {
+    Services.prefs.clearUserPref(CONTILE_CACHE_PREF);
+    Services.prefs.clearUserPref(CONTILE_CACHE_LAST_FETCH_PREF);
+    Services.prefs.clearUserPref(CONTILE_CACHE_VALID_FOR_PREF);
+  }
+
+  /**
+   * Filter the tiles whose sponsor is on the Top Sites sponsor blocklist.
+   *
+   * @param {Array} tiles
+   *   An array of the tile objects
+   */
+  _filterBlockedSponsors(tiles) {
+    const blocklist = JSON.parse(
+      Services.prefs.getStringPref(TOP_SITES_BLOCKED_SPONSORS_PREF, "[]")
+    );
+    return tiles.filter(tile => !blocklist.includes(shortURL(tile)));
+  }
+
+  /**
+   * Calculate the time Contile response is valid for based on cache-control header
+   *
+   * @param {string} cacheHeader
+   *   string value of the Contile resposne cache-control header
+   */
+  _extractCacheValidFor(cacheHeader) {
+    if (!cacheHeader) {
+      lazy.log.warn("Contile response cache control header is empty");
+      return 0;
+    }
+    const [, staleIfError] = cacheHeader.match(/stale-if-error=\s*([0-9]+)/i);
+    const [, maxAge] = cacheHeader.match(/max-age=\s*([0-9]+)/i);
+    const validFor =
+      Number.parseInt(staleIfError, 10) + Number.parseInt(maxAge, 10);
+    return isNaN(validFor) ? 0 : validFor;
+  }
+
+  /**
+   * Load Tiles from Contile Cache Prefs
+   */
+  _loadTilesFromCache() {
+    lazy.log.info("Contile client is trying to load tiles from local cache.");
+    const now = Math.round(Date.now() / 1000);
+    const lastFetch = Services.prefs.getIntPref(
+      CONTILE_CACHE_LAST_FETCH_PREF,
+      0
+    );
+    const validFor = Services.prefs.getIntPref(CONTILE_CACHE_VALID_FOR_PREF, 0);
+    this._topSitesFeed._telemetryUtility.setSponsoredTilesConfigured();
+    if (now <= lastFetch + validFor) {
+      try {
+        let cachedTiles = JSON.parse(
+          Services.prefs.getStringPref(CONTILE_CACHE_PREF)
+        );
+        this._topSitesFeed._telemetryUtility.setTiles(cachedTiles);
+        cachedTiles = this._filterBlockedSponsors(cachedTiles);
+        this._topSitesFeed._telemetryUtility.determineFilteredTilesAndSetToDismissed(
+          cachedTiles
+        );
+        this._sites = cachedTiles;
+        lazy.log.info("Local cache loaded.");
+        return true;
+      } catch (error) {
+        lazy.log.warn(`Failed to load tiles from local cache: ${error}.`);
+        return false;
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * Determine number of Tiles to get from Contile
+   */
+  _getMaxNumFromContile() {
+    return (
+      lazy.NimbusFeatures.pocketNewtab.getVariable(
+        NIMBUS_VARIABLE_CONTILE_MAX_NUM_SPONSORED
+      ) ?? CONTILE_MAX_NUM_SPONSORED
+    );
+  }
+
+  async _fetchSites() {
+    if (
+      !lazy.NimbusFeatures.newtab.getVariable(
+        NIMBUS_VARIABLE_CONTILE_ENABLED
+      ) ||
+      !this._topSitesFeed.store.getState().Prefs.values[SHOW_SPONSORED_PREF]
+    ) {
+      if (this._sites.length) {
+        this._sites = [];
+        return true;
+      }
+      return false;
+    }
+    try {
+      let url = Services.prefs.getStringPref(CONTILE_ENDPOINT_PREF);
+      const response = await this._topSitesFeed.fetch(url, {
+        credentials: "omit",
+      });
+      if (!response.ok) {
+        lazy.log.warn(
+          `Contile endpoint returned unexpected status: ${response.status}`
+        );
+        if (response.status === 304 || response.status >= 500) {
+          return this._loadTilesFromCache();
+        }
+      }
+
+      const lastFetch = Math.round(Date.now() / 1000);
+      Services.prefs.setIntPref(CONTILE_CACHE_LAST_FETCH_PREF, lastFetch);
+      this._topSitesFeed._telemetryUtility.setSponsoredTilesConfigured();
+
+      // Contile returns 204 indicating there is no content at the moment.
+      // If this happens, it will clear `this._sites` reset the cached tiles
+      // to an empty array.
+      if (response.status === 204) {
+        this._topSitesFeed._telemetryUtility.clearTilesForProvider(
+          SPONSORED_TILE_PARTNER_AMP
+        );
+        if (this._sites.length) {
+          this._sites = [];
+          Services.prefs.setStringPref(
+            CONTILE_CACHE_PREF,
+            JSON.stringify(this._sites)
+          );
+          return true;
+        }
+        return false;
+      }
+      const body = await response.json();
+
+      if (body?.sov) {
+        this._sov = JSON.parse(atob(body.sov));
+      }
+      if (body?.tiles && Array.isArray(body.tiles)) {
+        const useAdditionalTiles = lazy.NimbusFeatures.newtab.getVariable(
+          NIMBUS_VARIABLE_ADDITIONAL_TILES
+        );
+
+        const maxNumFromContile = this._getMaxNumFromContile();
+
+        let { tiles } = body;
+        this._topSitesFeed._telemetryUtility.setTiles(tiles);
+        if (
+          useAdditionalTiles !== undefined &&
+          !useAdditionalTiles &&
+          tiles.length > maxNumFromContile
+        ) {
+          tiles.length = maxNumFromContile;
+          this._topSitesFeed._telemetryUtility.determineFilteredTilesAndSetToOversold(
+            tiles
+          );
+        }
+        tiles = this._filterBlockedSponsors(tiles);
+        this._topSitesFeed._telemetryUtility.determineFilteredTilesAndSetToDismissed(
+          tiles
+        );
+        if (tiles.length > maxNumFromContile) {
+          lazy.log.info("Remove unused links from Contile");
+          tiles.length = maxNumFromContile;
+          this._topSitesFeed._telemetryUtility.determineFilteredTilesAndSetToOversold(
+            tiles
+          );
+        }
+        this._sites = tiles;
+        Services.prefs.setStringPref(
+          CONTILE_CACHE_PREF,
+          JSON.stringify(this._sites)
+        );
+        Services.prefs.setIntPref(
+          CONTILE_CACHE_VALID_FOR_PREF,
+          this._extractCacheValidFor(
+            response.headers.get("cache-control") ||
+              response.headers.get("Cache-Control")
+          )
+        );
+
+        return true;
+      }
+    } catch (error) {
+      lazy.log.warn(
+        `Failed to fetch data from Contile server: ${error.message}`
+      );
+      return this._loadTilesFromCache();
+    }
+    return false;
+  }
+}
+
+class _TopSites {
+  constructor() {
+    this._telemetryUtility = new TopSitesTelemetry();
+    this._contile = new ContileIntegration(this);
+    this._tippyTopProvider = new TippyTopProvider();
+    ChromeUtils.defineLazyGetter(
+      this,
+      "_currentSearchHostname",
+      getShortURLForCurrentSearch
+    );
+    this.dedupe = new Dedupe(this._dedupeKey);
+    this.frecentCache = new lazy.LinksCache(
+      lazy.NewTabUtils.activityStreamLinks,
+      "getTopSites",
+      CACHED_LINK_PROPS_TO_MIGRATE,
+      (oldOptions, newOptions) =>
+        // Refresh if no old options or requesting more items
+        !(oldOptions.numItems >= newOptions.numItems)
+    );
+    this.pinnedCache = new lazy.LinksCache(
+      lazy.NewTabUtils.pinnedLinks,
+      "links",
+      [...CACHED_LINK_PROPS_TO_MIGRATE, ...PINNED_FAVICON_PROPS_TO_MIGRATE]
+    );
+    lazy.PageThumbs.addExpirationFilter(this);
+    this._nimbusChangeListener = this._nimbusChangeListener.bind(this);
+  }
+
+  _nimbusChangeListener(event, reason) {
+    // The Nimbus API current doesn't specify the changed variable(s) in the
+    // listener callback, so we have to refresh unconditionally on every change
+    // of the `newtab` feature. It should be a manageable overhead given the
+    // current update cadence (6 hours) of Nimbus.
+    //
+    // Skip the experiment and rollout loading reasons since this feature has
+    // `isEarlyStartup` enabled, the feature variables are already available
+    // before the experiment or rollout loads.
+    if (
+      !["feature-experiment-loaded", "feature-rollout-loaded"].includes(reason)
+    ) {
+      this._contile.refresh();
+    }
+  }
+
+  init() {
+    // If the feed was previously disabled PREFS_INITIAL_VALUES was never received
+    this._readDefaults({ isStartup: true });
+    this._storage = this.store.dbStorage.getDbTable("sectionPrefs");
+    this._contile.refresh();
+    Services.obs.addObserver(this, "browser-search-engine-modified");
+    Services.obs.addObserver(this, "browser-region-updated");
+    Services.prefs.addObserver(REMOTE_SETTING_DEFAULTS_PREF, this);
+    Services.prefs.addObserver(DEFAULT_SITES_OVERRIDE_PREF, this);
+    Services.prefs.addObserver(DEFAULT_SITES_EXPERIMENTS_PREF_BRANCH, this);
+    lazy.NimbusFeatures.newtab.onUpdate(this._nimbusChangeListener);
+  }
+
+  uninit() {
+    lazy.PageThumbs.removeExpirationFilter(this);
+    Services.obs.removeObserver(this, "browser-search-engine-modified");
+    Services.obs.removeObserver(this, "browser-region-updated");
+    Services.prefs.removeObserver(REMOTE_SETTING_DEFAULTS_PREF, this);
+    Services.prefs.removeObserver(DEFAULT_SITES_OVERRIDE_PREF, this);
+    Services.prefs.removeObserver(DEFAULT_SITES_EXPERIMENTS_PREF_BRANCH, this);
+    lazy.NimbusFeatures.newtab.offUpdate(this._nimbusChangeListener);
+  }
+
+  observe(subj, topic, data) {
+    switch (topic) {
+      case "browser-search-engine-modified":
+        // We should update the current top sites if the search engine has been changed since
+        // the search engine that gets filtered out of top sites has changed.
+        // We also need to drop search shortcuts when their engine gets removed / hidden.
+        if (
+          data === "engine-default" &&
+          this.store.getState().Prefs.values[FILTER_DEFAULT_SEARCH_PREF]
+        ) {
+          delete this._currentSearchHostname;
+          this._currentSearchHostname = getShortURLForCurrentSearch();
+        }
+        this.refresh({ broadcast: true });
+        break;
+      case "browser-region-updated":
+        this._readDefaults();
+        break;
+      case "nsPref:changed":
+        if (
+          data === REMOTE_SETTING_DEFAULTS_PREF ||
+          data === DEFAULT_SITES_OVERRIDE_PREF ||
+          data.startsWith(DEFAULT_SITES_EXPERIMENTS_PREF_BRANCH)
+        ) {
+          this._readDefaults();
+        }
+        break;
+    }
+  }
+
+  _dedupeKey(site) {
+    return site && site.hostname;
+  }
+
+  /**
+   * _readDefaults - sets DEFAULT_TOP_SITES
+   */
+  async _readDefaults({ isStartup = false } = {}) {
+    this._useRemoteSetting = false;
+
+    if (!Services.prefs.getBoolPref(REMOTE_SETTING_DEFAULTS_PREF)) {
+      this.refreshDefaults(
+        this.store.getState().Prefs.values[DEFAULT_SITES_PREF],
+        { isStartup }
+      );
+      return;
+    }
+
+    // Try using default top sites from enterprise policies or tests. The pref
+    // is locked when set via enterprise policy. Tests have no default sites
+    // unless they set them via this pref.
+    if (
+      Services.prefs.prefIsLocked(DEFAULT_SITES_OVERRIDE_PREF) ||
+      Cu.isInAutomation
+    ) {
+      let sites = Services.prefs.getStringPref(DEFAULT_SITES_OVERRIDE_PREF, "");
+      this.refreshDefaults(sites, { isStartup });
+      return;
+    }
+
+    // Clear out the array of any previous defaults.
+    DEFAULT_TOP_SITES.length = 0;
+
+    // Read defaults from contile.
+    const contileEnabled = lazy.NimbusFeatures.newtab.getVariable(
+      NIMBUS_VARIABLE_CONTILE_ENABLED
+    );
+
+    // Keep the number of positions in the array in sync with CONTILE_MAX_NUM_SPONSORED.
+    // sponsored_position is a 1-based index, and contilePositions is a 0-based index,
+    // so we need to add 1 to each of these.
+    // Also currently this does not work with SOV.
+    let contilePositions = lazy.NimbusFeatures.pocketNewtab
+      .getVariable(NIMBUS_VARIABLE_CONTILE_POSITIONS)
+      ?.split(",")
+      .map(item => parseInt(item, 10) + 1)
+      .filter(item => !Number.isNaN(item));
+    if (!contilePositions || contilePositions.length === 0) {
+      contilePositions = [1, 2];
+    }
+
+    let hasContileTiles = false;
+    if (contileEnabled) {
+      let contilePositionIndex = 0;
+      // We need to loop through potential spocs and set their positions.
+      // If we run out of spocs or positions, we stop.
+      // First, we need to know which array is shortest. This is our exit condition.
+      const minLength = Math.min(
+        contilePositions.length,
+        this._contile.sites.length
+      );
+      // Loop until we run out of spocs or positions.
+      for (let i = 0; i < minLength; i++) {
+        let site = this._contile.sites[i];
+        let hostname = shortURL(site);
+        let link = {
+          isDefault: true,
+          url: site.url,
+          hostname,
+          sendAttributionRequest: false,
+          label: site.name,
+          show_sponsored_label: hostname !== "yandex",
+          sponsored_position: contilePositions[contilePositionIndex++],
+          sponsored_click_url: site.click_url,
+          sponsored_impression_url: site.impression_url,
+          sponsored_tile_id: site.id,
+          partner: SPONSORED_TILE_PARTNER_AMP,
+        };
+        if (site.image_url && site.image_size >= MIN_FAVICON_SIZE) {
+          // Only use the image from Contile if it's hi-res, otherwise, fallback
+          // to the built-in favicons.
+          link.favicon = site.image_url;
+          link.faviconSize = site.image_size;
+        }
+        DEFAULT_TOP_SITES.push(link);
+      }
+      hasContileTiles = contilePositionIndex > 0;
+      //This is to catch where we receive 3 tiles but reduce to 2 early in the filtering, before blocked list applied.
+      this._telemetryUtility.determineFilteredTilesAndSetToOversold(
+        DEFAULT_TOP_SITES
+      );
+    }
+
+    // Read defaults from remote settings.
+    this._useRemoteSetting = true;
+    let remoteSettingData = await this._getRemoteConfig();
+
+    const sponsoredBlocklist = JSON.parse(
+      Services.prefs.getStringPref(TOP_SITES_BLOCKED_SPONSORS_PREF, "[]")
+    );
+
+    for (let siteData of remoteSettingData) {
+      let hostname = shortURL(siteData);
+      // Drop default sites when Contile already provided a sponsored one with
+      // the same host name.
+      if (
+        contileEnabled &&
+        DEFAULT_TOP_SITES.findIndex(site => site.hostname === hostname) > -1
+      ) {
+        continue;
+      }
+      // Also drop those sponsored sites that were blocked by the user before
+      // with the same hostname.
+      if (
+        siteData.sponsored_position &&
+        sponsoredBlocklist.includes(hostname)
+      ) {
+        continue;
+      }
+      let link = {
+        isDefault: true,
+        url: siteData.url,
+        hostname,
+        sendAttributionRequest: !!siteData.send_attribution_request,
+      };
+      if (siteData.url_urlbar_override) {
+        link.url_urlbar = siteData.url_urlbar_override;
+      }
+      if (siteData.title) {
+        link.label = siteData.title;
+      }
+      if (siteData.search_shortcut) {
+        link = await this.topSiteToSearchTopSite(link);
+      } else if (siteData.sponsored_position) {
+        if (contileEnabled && hasContileTiles) {
+          continue;
+        }
+        const {
+          sponsored_position,
+          sponsored_tile_id,
+          sponsored_impression_url,
+          sponsored_click_url,
+        } = siteData;
+        link = {
+          sponsored_position,
+          sponsored_tile_id,
+          sponsored_impression_url,
+          sponsored_click_url,
+          show_sponsored_label: link.hostname !== "yandex",
+          ...link,
+        };
+      }
+      DEFAULT_TOP_SITES.push(link);
+    }
+
+    this.refresh({ broadcast: true, isStartup });
+  }
+
+  refreshDefaults(sites, { isStartup = false } = {}) {
+    // Clear out the array of any previous defaults
+    DEFAULT_TOP_SITES.length = 0;
+
+    // Add default sites if any based on the pref
+    if (sites) {
+      for (const url of sites.split(",")) {
+        const site = {
+          isDefault: true,
+          url,
+        };
+        site.hostname = shortURL(site);
+        DEFAULT_TOP_SITES.push(site);
+      }
+    }
+
+    this.refresh({ broadcast: true, isStartup });
+  }
+
+  async _getRemoteConfig(firstTime = true) {
+    if (!this._remoteConfig) {
+      this._remoteConfig = await lazy.RemoteSettings("top-sites");
+      this._remoteConfig.on("sync", () => {
+        this._readDefaults();
+      });
+    }
+
+    let result = [];
+    let failed = false;
+    try {
+      result = await this._remoteConfig.get();
+    } catch (ex) {
+      console.error(ex);
+      failed = true;
+    }
+    if (!result.length) {
+      console.error("Received empty top sites configuration!");
+      failed = true;
+    }
+    // If we failed, or the result is empty, try loading from the local dump.
+    if (firstTime && failed) {
+      await this._remoteConfig.db.clear();
+      // Now call this again.
+      return this._getRemoteConfig(false);
+    }
+
+    // Sort sites based on the "order" attribute.
+    result.sort((a, b) => a.order - b.order);
+
+    result = result.filter(topsite => {
+      // Filter by region.
+      if (topsite.exclude_regions?.includes(lazy.Region.home)) {
+        return false;
+      }
+      if (
+        topsite.include_regions?.length &&
+        !topsite.include_regions.includes(lazy.Region.home)
+      ) {
+        return false;
+      }
+
+      // Filter by locale.
+      if (topsite.exclude_locales?.includes(Services.locale.appLocaleAsBCP47)) {
+        return false;
+      }
+      if (
+        topsite.include_locales?.length &&
+        !topsite.include_locales.includes(Services.locale.appLocaleAsBCP47)
+      ) {
+        return false;
+      }
+
+      // Filter by experiment.
+      // Exclude this top site if any of the specified experiments are running.
+      if (
+        topsite.exclude_experiments?.some(experimentID =>
+          Services.prefs.getBoolPref(
+            DEFAULT_SITES_EXPERIMENTS_PREF_BRANCH + experimentID,
+            false
+          )
+        )
+      ) {
+        return false;
+      }
+      // Exclude this top site if none of the specified experiments are running.
+      if (
+        topsite.include_experiments?.length &&
+        topsite.include_experiments.every(
+          experimentID =>
+            !Services.prefs.getBoolPref(
+              DEFAULT_SITES_EXPERIMENTS_PREF_BRANCH + experimentID,
+              false
+            )
+        )
+      ) {
+        return false;
+      }
+
+      return true;
+    });
+
+    return result;
+  }
+
+  filterForThumbnailExpiration(callback) {
+    const { rows } = this.store.getState().TopSites;
+    callback(
+      rows.reduce((acc, site) => {
+        acc.push(site.url);
+        if (site.customScreenshotURL) {
+          acc.push(site.customScreenshotURL);
+        }
+        return acc;
+      }, [])
+    );
+  }
+
+  /**
+   * shouldFilterSearchTile - is default filtering enabled and does a given hostname match the user's default search engine?
+   *
+   * @param {string} hostname a top site hostname, such as "amazon" or "foo"
+   * @returns {bool}
+   */
+  shouldFilterSearchTile(hostname) {
+    if (
+      this.store.getState().Prefs.values[FILTER_DEFAULT_SEARCH_PREF] &&
+      (SEARCH_FILTERS.includes(hostname) ||
+        hostname === this._currentSearchHostname)
+    ) {
+      return true;
+    }
+    return false;
+  }
+
+  /**
+   * _maybeInsertSearchShortcuts - if the search shortcuts experiment is running,
+   *                               insert search shortcuts if needed
+   *
+   * @param {Array} plainPinnedSites (from the pinnedSitesCache)
+   * @returns {boolean} Did we insert any search shortcuts?
+   */
+  async _maybeInsertSearchShortcuts(plainPinnedSites) {
+    // Only insert shortcuts if the experiment is running
+    if (this.store.getState().Prefs.values[SEARCH_SHORTCUTS_EXPERIMENT]) {
+      // We don't want to insert shortcuts we've previously inserted
+      const prevInsertedShortcuts = this.store
+        .getState()
+        .Prefs.values[SEARCH_SHORTCUTS_HAVE_PINNED_PREF].split(",")
+        .filter(s => s); // Filter out empty strings
+      const newInsertedShortcuts = [];
+
+      let shouldPin = this._useRemoteSetting
+        ? DEFAULT_TOP_SITES.filter(s => s.searchTopSite).map(s => s.hostname)
+        : this.store
+            .getState()
+            .Prefs.values[SEARCH_SHORTCUTS_SEARCH_ENGINES_PREF].split(",");
+      shouldPin = shouldPin
+        .map(getSearchProvider)
+        .filter(s => s && s.shortURL !== this._currentSearchHostname);
+
+      // If we've previously inserted all search shortcuts return early
+      if (
+        shouldPin.every(shortcut =>
+          prevInsertedShortcuts.includes(shortcut.shortURL)
+        )
+      ) {
+        return false;
+      }
+
+      const numberOfSlots =
+        this.store.getState().Prefs.values[ROWS_PREF] *
+        TOP_SITES_MAX_SITES_PER_ROW;
+
+      // The plainPinnedSites array is populated with pinned sites at their
+      // respective indices, and null everywhere else, but is not always the
+      // right length
+      const emptySlots = Math.max(numberOfSlots - plainPinnedSites.length, 0);
+      const pinnedSites = [...plainPinnedSites].concat(
+        Array(emptySlots).fill(null)
+      );
+
+      const tryToInsertSearchShortcut = async shortcut => {
+        const nextAvailable = pinnedSites.indexOf(null);
+        // Only add a search shortcut if the site isn't already pinned, we
+        // haven't previously inserted it, there's space to pin it, and the
+        // search engine is available in Firefox
+        if (
+          !pinnedSites.find(s => s && shortURL(s) === shortcut.shortURL) &&
+          !prevInsertedShortcuts.includes(shortcut.shortURL) &&
+          nextAvailable > -1 &&
+          (await checkHasSearchEngine(shortcut.keyword))
+        ) {
+          const site = await this.topSiteToSearchTopSite({ url: shortcut.url });
+          this._pinSiteAt(site, nextAvailable);
+          pinnedSites[nextAvailable] = site;
+          newInsertedShortcuts.push(shortcut.shortURL);
+        }
+      };
+
+      for (let shortcut of shouldPin) {
+        await tryToInsertSearchShortcut(shortcut);
+      }
+
+      if (newInsertedShortcuts.length) {
+        this.store.dispatch(
+          ac.SetPref(
+            SEARCH_SHORTCUTS_HAVE_PINNED_PREF,
+            prevInsertedShortcuts.concat(newInsertedShortcuts).join(",")
+          )
+        );
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * This thin wrapper around global.fetch makes it easier for us to write
+   * automated tests that simulate responses from this fetch.
+   */
+  fetch(...args) {
+    return fetch(...args);
+  }
+
+  /**
+   * Fetch topsites spocs from the DiscoveryStream feed.
+   *
+   * @returns {Array} An array of sponsored tile objects.
+   */
+  fetchDiscoveryStreamSpocs() {
+    let sponsored = [];
+    const { DiscoveryStream } = this.store.getState();
+    if (DiscoveryStream) {
+      const discoveryStreamSpocs =
+        DiscoveryStream.spocs.data["sponsored-topsites"]?.items || [];
+      // Find the first component of a type and remove it from layout
+      const findSponsoredTopsitesPositions = name => {
+        for (const row of DiscoveryStream.layout) {
+          for (const component of row.components) {
+            if (component.placement?.name === name) {
+              return component.spocs.positions;
+            }
+          }
+        }
+        return null;
+      };
+
+      // Get positions from layout for now. This could be improved if we store position data in state.
+      const discoveryStreamSpocPositions =
+        findSponsoredTopsitesPositions("sponsored-topsites");
+
+      if (discoveryStreamSpocPositions?.length) {
+        function reformatImageURL(url, width, height) {
+          // Change the image URL to request a size tailored for the parent container width
+          // Also: force JPEG, quality 60, no upscaling, no EXIF data
+          // Uses Thumbor: https://thumbor.readthedocs.io/en/latest/usage.html
+          // For now we wrap this in single quotes because this is being used in a url() css rule, and otherwise would cause a parsing error.
+          return `'https://img-getpocket.cdn.mozilla.net/${width}x${height}/filters:format(jpeg):quality(60):no_upscale():strip_exif()/${encodeURIComponent(
+            url
+          )}'`;
+        }
+
+        // We need to loop through potential spocs and set their positions.
+        // If we run out of spocs or positions, we stop.
+        // First, we need to know which array is shortest. This is our exit condition.
+        const minLength = Math.min(
+          discoveryStreamSpocPositions.length,
+          discoveryStreamSpocs.length
+        );
+        // Loop until we run out of spocs or positions.
+        for (let i = 0; i < minLength; i++) {
+          const positionIndex = discoveryStreamSpocPositions[i].index;
+          const spoc = discoveryStreamSpocs[i];
+          const link = {
+            favicon: reformatImageURL(spoc.raw_image_src, 96, 96),
+            faviconSize: 96,
+            type: "SPOC",
+            label: spoc.title || spoc.sponsor,
+            title: spoc.title || spoc.sponsor,
+            url: spoc.url,
+            flightId: spoc.flight_id,
+            id: spoc.id,
+            guid: spoc.id,
+            shim: spoc.shim,
+            // For now we are assuming position based on intended position.
+            // Actual position can shift based on other content.
+            // We send the intended position in the ping.
+            pos: positionIndex,
+            // Set this so that SPOC topsites won't be shown in the URL bar.
+            // See Bug 1822027. Note that `sponsored_position` is 1-based.
+            sponsored_position: positionIndex + 1,
+            // This is used for topsites deduping.
+            hostname: shortURL({ url: spoc.url }),
+            partner: SPONSORED_TILE_PARTNER_MOZ_SALES,
+          };
+          sponsored.push(link);
+        }
+      }
+    }
+    return sponsored;
+  }
+
+  // eslint-disable-next-line max-statements
+  async getLinksWithDefaults(isStartup = false) {
+    const prefValues = this.store.getState().Prefs.values;
+    const numItems = prefValues[ROWS_PREF] * TOP_SITES_MAX_SITES_PER_ROW;
+    const searchShortcutsExperiment = prefValues[SEARCH_SHORTCUTS_EXPERIMENT];
+    // We must wait for search services to initialize in order to access default
+    // search engine properties without triggering a synchronous initialization
+    try {
+      await Services.search.init();
+    } catch {
+      // We continue anyway because we want the user to see their sponsored,
+      // saved, or visited shortcut tiles even if search engines are not
+      // available.
+    }
+
+    // Get all frecent sites from history.
+    let frecent = [];
+    let cache;
+    try {
+      // Request can throw if executing the linkGetter inside LinksCache returns
+      // a null object.
+      cache = await this.frecentCache.request({
+        // We need to overquery due to the top 5 alexa search + default search possibly being removed
+        numItems: numItems + SEARCH_FILTERS.length + 1,
+        topsiteFrecency: FRECENCY_THRESHOLD,
+      });
+    } catch (ex) {
+      cache = [];
+    }
+
+    for (let link of cache) {
+      // The cache can contain null values.
+      if (!link) {
+        continue;
+      }
+      const hostname = shortURL(link);
+      if (!this.shouldFilterSearchTile(hostname)) {
+        frecent.push({
+          ...(searchShortcutsExperiment
+            ? await this.topSiteToSearchTopSite(link)
+            : link),
+          hostname,
+        });
+      }
+    }
+
+    // Get defaults.
+    let contileSponsored = [];
+    let notBlockedDefaultSites = [];
+    for (let link of DEFAULT_TOP_SITES) {
+      // For sponsored Yandex links, default filtering is reversed: we only
+      // show them if Yandex is the default search engine.
+      if (link.sponsored_position && link.hostname === "yandex") {
+        if (link.hostname !== this._currentSearchHostname) {
+          continue;
+        }
+      } else if (this.shouldFilterSearchTile(link.hostname)) {
+        continue;
+      }
+      // Drop blocked default sites.
+      if (
+        lazy.NewTabUtils.blockedLinks.isBlocked({
+          url: link.url,
+        })
+      ) {
+        continue;
+      }
+      // If we've previously blocked a search shortcut, remove the default top site
+      // that matches the hostname
+      const searchProvider = getSearchProvider(shortURL(link));
+      if (
+        searchProvider &&
+        lazy.NewTabUtils.blockedLinks.isBlocked({ url: searchProvider.url })
+      ) {
+        continue;
+      }
+      if (link.sponsored_position) {
+        if (!prefValues[SHOW_SPONSORED_PREF]) {
+          continue;
+        }
+        contileSponsored[link.sponsored_position - 1] = link;
+
+        // Unpin search shortcut if present for the sponsored link to be shown
+        // instead.
+        this._unpinSearchShortcut(link.hostname);
+      } else {
+        notBlockedDefaultSites.push(
+          searchShortcutsExperiment
+            ? await this.topSiteToSearchTopSite(link)
+            : link
+        );
+      }
+    }
+    this._telemetryUtility.determineFilteredTilesAndSetToDismissed(
+      contileSponsored
+    );
+
+    const discoverySponsored = this.fetchDiscoveryStreamSpocs();
+    this._telemetryUtility.setTiles(discoverySponsored);
+
+    const sponsored = this._mergeSponsoredLinks({
+      [SPONSORED_TILE_PARTNER_AMP]: contileSponsored,
+      [SPONSORED_TILE_PARTNER_MOZ_SALES]: discoverySponsored,
+    });
+
+    this._maybeCapSponsoredLinks(sponsored);
+
+    // This will set all extra tiles to oversold, including moz-sales.
+    this._telemetryUtility.determineFilteredTilesAndSetToOversold(sponsored);
+
+    // Get pinned links augmented with desired properties
+    let plainPinned = await this.pinnedCache.request();
+
+    // Insert search shortcuts if we need to.
+    // _maybeInsertSearchShortcuts returns true if any search shortcuts are
+    // inserted, meaning we need to expire and refresh the pinnedCache
+    if (await this._maybeInsertSearchShortcuts(plainPinned)) {
+      this.pinnedCache.expire();
+      plainPinned = await this.pinnedCache.request();
+    }
+
+    const pinned = await Promise.all(
+      plainPinned.map(async link => {
+        if (!link) {
+          return link;
+        }
+
+        // Drop pinned search shortcuts when their engine has been removed / hidden.
+        if (link.searchTopSite) {
+          const searchProvider = getSearchProvider(shortURL(link));
+          if (
+            !searchProvider ||
+            !(await checkHasSearchEngine(searchProvider.keyword))
+          ) {
+            return null;
+          }
+        }
+
+        // Copy all properties from a frecent link and add more
+        const finder = other => other.url === link.url;
+
+        // Remove frecent link's screenshot if pinned link has a custom one
+        const frecentSite = frecent.find(finder);
+        if (frecentSite && link.customScreenshotURL) {
+          delete frecentSite.screenshot;
+        }
+        // If the link is a frecent site, do not copy over 'isDefault', else check
+        // if the site is a default site
+        const copy = Object.assign(
+          {},
+          frecentSite || { isDefault: !!notBlockedDefaultSites.find(finder) },
+          link,
+          { hostname: shortURL(link) },
+          { searchTopSite: !!link.searchTopSite }
+        );
+
+        // Add in favicons if we don't already have it
+        if (!copy.favicon) {
+          try {
+            lazy.NewTabUtils.activityStreamProvider._faviconBytesToDataURI(
+              await lazy.NewTabUtils.activityStreamProvider._addFavicons([copy])
+            );
+
+            for (const prop of PINNED_FAVICON_PROPS_TO_MIGRATE) {
+              copy.__sharedCache.updateLink(prop, copy[prop]);
+            }
+          } catch (e) {
+            // Some issue with favicon, so just continue without one
+          }
+        }
+
+        return copy;
+      })
+    );
+
+    // Remove any duplicates from frecent and default sites
+    const [, dedupedSponsored, dedupedFrecent, dedupedDefaults] =
+      this.dedupe.group(pinned, sponsored, frecent, notBlockedDefaultSites);
+    const dedupedUnpinned = [...dedupedFrecent, ...dedupedDefaults];
+
+    // Remove adult sites if we need to
+    const checkedAdult = lazy.FilterAdult.filter(dedupedUnpinned);
+
+    // Insert the original pinned sites into the deduped frecent and defaults.
+    let withPinned = insertPinned(checkedAdult, pinned);
+    // Insert sponsored sites at their desired position.
+    dedupedSponsored.forEach(link => {
+      if (!link) {
+        return;
+      }
+      let index = link.sponsored_position - 1;
+      if (index >= withPinned.length) {
+        withPinned[index] = link;
+      } else if (withPinned[index]?.sponsored_position) {
+        // We currently want DiscoveryStream spocs to replace existing spocs.
+        withPinned[index] = link;
+      } else {
+        withPinned.splice(index, 0, link);
+      }
+    });
+    // Remove excess items after we inserted sponsored ones.
+    withPinned = withPinned.slice(0, numItems);
+
+    // Now, get a tippy top icon, a rich icon, or screenshot for every item
+    for (const link of withPinned) {
+      if (link) {
+        // If there is a custom screenshot this is the only image we display
+        if (link.customScreenshotURL) {
+          this._fetchScreenshot(link, link.customScreenshotURL, isStartup);
+        } else if (link.searchTopSite && !link.isDefault) {
+          await this._attachTippyTopIconForSearchShortcut(link, link.label);
+        } else {
+          this._fetchIcon(link, isStartup);
+        }
+
+        // Remove internal properties that might be updated after dispatch
+        delete link.__sharedCache;
+
+        // Indicate that these links should get a frecency bonus when clicked
+        link.typedBonus = true;
+      }
+    }
+
+    this._linksWithDefaults = withPinned;
+
+    this._telemetryUtility.finalizeNewtabPingFields(dedupedSponsored);
+    return withPinned;
+  }
+
+  /**
+   * Cap sponsored links if they're more than the specified maximum.
+   *
+   * @param {Array} links An array of sponsored links. Capping will be performed in-place.
+   */
+  _maybeCapSponsoredLinks(links) {
+    // Set maximum sponsored top sites
+    const maxSponsored =
+      lazy.NimbusFeatures.pocketNewtab.getVariable(
+        NIMBUS_VARIABLE_MAX_SPONSORED
+      ) ?? MAX_NUM_SPONSORED;
+    if (links.length > maxSponsored) {
+      links.length = maxSponsored;
+    }
+  }
+
+  /**
+   * Merge sponsored links from all the partners using SOV if present.
+   * For each tile position, the user is assigned to one partner via stable sampling.
+   * If the chosen partner doesn't have a tile to serve, another tile from a different
+   * partner is used as the replacement.
+   *
+   * @param {object} sponsoredLinks An object with sponsored links from all the partners.
+   * @returns {Array} An array of merged sponsored links.
+   */
+  _mergeSponsoredLinks(sponsoredLinks) {
+    const { positions: allocatedPositions, ready: sovReady } =
+      this.store.getState().TopSites.sov || {};
+    if (
+      !this._contile.sov ||
+      !sovReady ||
+      !lazy.NimbusFeatures.pocketNewtab.getVariable(
+        NIMBUS_VARIABLE_CONTILE_SOV_ENABLED
+      )
+    ) {
+      return Object.values(sponsoredLinks).flat();
+    }
+
+    // AMP links might have empty slots, remove them as SOV doesn't need those.
+    sponsoredLinks[SPONSORED_TILE_PARTNER_AMP] =
+      sponsoredLinks[SPONSORED_TILE_PARTNER_AMP].filter(Boolean);
+
+    let sponsored = [];
+    let chosenPartners = [];
+
+    for (const allocation of allocatedPositions) {
+      let link = null;
+      const { assignedPartner } = allocation;
+      if (assignedPartner) {
+        // Unknown partners are allowed so that new parters can be added to Shepherd
+        // sooner without waiting for client changes.
+        link = sponsoredLinks[assignedPartner]?.shift();
+      }
+
+      if (!link) {
+        // If the chosen partner doesn't have a tile for this postion, choose any
+        // one from another group. For simplicity, we do _not_ do resampling here
+        // against the remaining partners.
+        for (const partner of SPONSORED_TILE_PARTNERS) {
+          if (
+            partner === assignedPartner ||
+            sponsoredLinks[partner].length === 0
+          ) {
+            continue;
+          }
+          link = sponsoredLinks[partner].shift();
+          break;
+        }
+
+        if (!link) {
+          // No more links to be added across all the partners, just return.
+          if (chosenPartners.length) {
+            Glean.newtab.sovAllocation.set(
+              chosenPartners.map(entry => JSON.stringify(entry))
+            );
+          }
+          return sponsored;
+        }
+      }
+
+      // Update the position fields. Note that postion is also 1-based in SOV.
+      link.sponsored_position = allocation.position;
+      if (link.pos !== undefined) {
+        // Pocket `pos` is 0-based.
+        link.pos = allocation.position - 1;
+      }
+      sponsored.push(link);
+
+      chosenPartners.push({
+        pos: allocation.position,
+        assigned: assignedPartner, // The assigned partner based on SOV
+        chosen: link.partner,
+      });
+    }
+    // Record chosen partners to glean
+    if (chosenPartners.length) {
+      Glean.newtab.sovAllocation.set(
+        chosenPartners.map(entry => JSON.stringify(entry))
+      );
+    }
+
+    // add the remaining contile sponsoredLinks when nimbus variable present
+    if (
+      lazy.NimbusFeatures.pocketNewtab.getVariable(
+        NIMBUS_VARIABLE_CONTILE_MAX_NUM_SPONSORED
+      )
+    ) {
+      return sponsored.concat(sponsoredLinks[SPONSORED_TILE_PARTNER_AMP]);
+    }
+
+    return sponsored;
+  }
+
+  /**
+   * Attach TippyTop icon to the given search shortcut
+   *
+   * Note that it queries the search form URL from search service For Yandex,
+   * and uses it to choose the best icon for its shortcut variants.
+   *
+   * @param {object} link A link object with a `url` property
+   * @param {string} keyword Search keyword
+   */
+  async _attachTippyTopIconForSearchShortcut(link, keyword) {
+    if (
+      ["@\u044F\u043D\u0434\u0435\u043A\u0441", "@yandex"].includes(keyword)
+    ) {
+      let site = { url: link.url };
+      site.url = (await getSearchFormURL(keyword)) || site.url;
+      this._tippyTopProvider.processSite(site);
+      link.tippyTopIcon = site.tippyTopIcon;
+      link.smallFavicon = site.smallFavicon;
+      link.backgroundColor = site.backgroundColor;
+    } else {
+      this._tippyTopProvider.processSite(link);
+    }
+  }
+
+  /**
+   * Refresh the top sites data for content.
+   *
+   * @param {object} options
+   * @param {bool} options.broadcast Should the update be broadcasted.
+   * @param {bool} options.isStartup Being called while TopSitesFeed is initting.
+   */
+  async refresh(options = {}) {
+    // Avoiding refreshing if it's already happening.
+    if (this._refreshing) {
+      return;
+    }
+    if (!this._startedUp && !options.isStartup) {
+      // Initial refresh still pending.
+      return;
+    }
+    this._refreshing = true;
+    this._startedUp = true;
+
+    if (!this._tippyTopProvider.initialized) {
+      await this._tippyTopProvider.init();
+    }
+
+    const links = await this.getLinksWithDefaults({
+      isStartup: options.isStartup,
+    });
+    const newAction = { type: at.TOP_SITES_UPDATED, data: { links } };
+    let storedPrefs;
+    try {
+      storedPrefs = (await this._storage.get(SECTION_ID)) || {};
+    } catch (e) {
+      storedPrefs = {};
+      console.error("Problem getting stored prefs for TopSites");
+    }
+    newAction.data.pref = getDefaultOptions(storedPrefs);
+
+    if (options.isStartup) {
+      newAction.meta = {
+        isStartup: true,
+      };
+    }
+
+    if (options.broadcast) {
+      // Broadcast an update to all open content pages
+      this.store.dispatch(ac.BroadcastToContent(newAction));
+    } else {
+      // Don't broadcast only update the state and update the preloaded tab.
+      this.store.dispatch(ac.AlsoToPreloaded(newAction));
+    }
+    this._refreshing = false;
+    if (Cu.isInAutomation) {
+      Services.obs.notifyObservers(null, "topsites-refreshed");
+    }
+  }
+
+  // Allocate ad positions to partners based on SOV via stable randomization.
+  async allocatePositions() {
+    // If the fetch to get sov fails for whatever reason, we can just return here.
+    // Code that uses this falls back to flattening allocations instead if this has failed.
+    if (!this._contile.sov) {
+      return;
+    }
+    // This sample input should ensure we return the same result for this allocation,
+    // even if called from other parts of the code.
+    const sampleInput = `${lazy.contextId}-${this._contile.sov.name}`;
+    const allocatedPositions = [];
+    for (const allocation of this._contile.sov.allocations) {
+      const allocatedPosition = {
+        position: allocation.position,
+      };
+      allocatedPositions.push(allocatedPosition);
+      const ratios = allocation.allocation.map(alloc => alloc.percentage);
+      if (ratios.length) {
+        const index = await lazy.Sampling.ratioSample(sampleInput, ratios);
+        allocatedPosition.assignedPartner =
+          allocation.allocation[index].partner;
+      }
+    }
+
+    this.store.dispatch(
+      ac.OnlyToMain({
+        type: at.SOV_UPDATED,
+        data: {
+          ready: !!allocatedPositions.length,
+          positions: allocatedPositions,
+        },
+      })
+    );
+  }
+
+  async updateCustomSearchShortcuts(isStartup = false) {
+    if (!this.store.getState().Prefs.values[SEARCH_SHORTCUTS_EXPERIMENT]) {
+      return;
+    }
+
+    if (!this._tippyTopProvider.initialized) {
+      await this._tippyTopProvider.init();
+    }
+
+    // Populate the state with available search shortcuts
+    let searchShortcuts = [];
+    for (const engine of await Services.search.getAppProvidedEngines()) {
+      const shortcut = CUSTOM_SEARCH_SHORTCUTS.find(s =>
+        engine.aliases.includes(s.keyword)
+      );
+      if (shortcut) {
+        let clone = { ...shortcut };
+        await this._attachTippyTopIconForSearchShortcut(clone, clone.keyword);
+        searchShortcuts.push(clone);
+      }
+    }
+
+    this.store.dispatch(
+      ac.BroadcastToContent({
+        type: at.UPDATE_SEARCH_SHORTCUTS,
+        data: { searchShortcuts },
+        meta: {
+          isStartup,
+        },
+      })
+    );
+  }
+
+  async topSiteToSearchTopSite(site) {
+    const searchProvider = getSearchProvider(shortURL(site));
+    if (
+      !searchProvider ||
+      !(await checkHasSearchEngine(searchProvider.keyword))
+    ) {
+      return site;
+    }
+    return {
+      ...site,
+      searchTopSite: true,
+      label: searchProvider.keyword,
+    };
+  }
+
+  /**
+   * Get an image for the link preferring tippy top, rich favicon, screenshots.
+   */
+  async _fetchIcon(link, isStartup = false) {
+    // Nothing to do if we already have a rich icon from the page
+    if (link.favicon && link.faviconSize >= MIN_FAVICON_SIZE) {
+      return;
+    }
+
+    // Nothing more to do if we can use a default tippy top icon
+    this._tippyTopProvider.processSite(link);
+    if (link.tippyTopIcon) {
+      return;
+    }
+
+    // Make a request for a better icon
+    this._requestRichIcon(link.url);
+
+    // Also request a screenshot if we don't have one yet
+    await this._fetchScreenshot(link, link.url, isStartup);
+  }
+
+  /**
+   * Fetch, cache and broadcast a screenshot for a specific topsite.
+   *
+   * @param {object} link cached topsite object
+   * @param {string} url where to fetch the image from
+   * @param {boolean} isStartup Whether the screenshot is fetched while
+   * initting TopSitesFeed.
+   */
+  async _fetchScreenshot(link, url, isStartup = false) {
+    // We shouldn't bother caching screenshots if they won't be shown.
+    if (
+      link.screenshot ||
+      !this.store.getState().Prefs.values[SHOWN_ON_NEWTAB_PREF]
+    ) {
+      return;
+    }
+    await lazy.Screenshots.maybeCacheScreenshot(
+      link,
+      url,
+      "screenshot",
+      screenshot =>
+        this.store.dispatch(
+          ac.BroadcastToContent({
+            data: { screenshot, url: link.url },
+            type: at.SCREENSHOT_UPDATED,
+            meta: {
+              isStartup,
+            },
+          })
+        )
+    );
+  }
+
+  /**
+   * Dispatch screenshot preview to target or notify if request failed.
+   *
+   * @param {string} url The URL used to capture the screenshot
+   * @param {string} target Id of content process where to dispatch the result
+   */
+  async getScreenshotPreview(url, target) {
+    const preview = (await lazy.Screenshots.getScreenshotForURL(url)) || "";
+    this.store.dispatch(
+      ac.OnlyToOneContent(
+        {
+          data: { url, preview },
+          type: at.PREVIEW_RESPONSE,
+        },
+        target
+      )
+    );
+  }
+
+  _requestRichIcon(url) {
+    this.store.dispatch({
+      type: at.RICH_ICON_MISSING,
+      data: { url },
+    });
+  }
+
+  updateSectionPrefs(collapsed) {
+    this.store.dispatch(
+      ac.BroadcastToContent({
+        type: at.TOP_SITES_PREFS_UPDATED,
+        data: { pref: collapsed },
+      })
+    );
+  }
+
+  /**
+   * Inform others that top sites data has been updated due to pinned changes.
+   */
+  _broadcastPinnedSitesUpdated() {
+    // Pinned data changed, so make sure we get latest
+    this.pinnedCache.expire();
+
+    // Refresh to update pinned sites with screenshots, trigger deduping, etc.
+    this.refresh({ broadcast: true });
+  }
+
+  /**
+   * Pin a site at a specific position saving only the desired keys.
+   *
+   * @param customScreenshotURL {string} User set URL of preview image for site
+   * @param label {string} User set string of custom site name
+   */
+  // To refactor in Bug 1891997
+  /* eslint-enable jsdoc/check-param-names */
+  async _pinSiteAt({ customScreenshotURL, label, url, searchTopSite }, index) {
+    const toPin = { url };
+    if (label) {
+      toPin.label = label;
+    }
+    if (customScreenshotURL) {
+      toPin.customScreenshotURL = customScreenshotURL;
+    }
+    if (searchTopSite) {
+      toPin.searchTopSite = searchTopSite;
+    }
+    lazy.NewTabUtils.pinnedLinks.pin(toPin, index);
+
+    await this._clearLinkCustomScreenshot({ customScreenshotURL, url });
+  }
+
+  async _clearLinkCustomScreenshot(site) {
+    // If screenshot url changed or was removed we need to update the cached link obj
+    if (site.customScreenshotURL !== undefined) {
+      const pinned = await this.pinnedCache.request();
+      const link = pinned.find(pin => pin && pin.url === site.url);
+      if (link && link.customScreenshotURL !== site.customScreenshotURL) {
+        link.__sharedCache.updateLink("screenshot", undefined);
+      }
+    }
+  }
+
+  /**
+   * Handle a pin action of a site to a position.
+   */
+  async pin(action) {
+    let { site, index } = action.data;
+    index = this._adjustPinIndexForSponsoredLinks(site, index);
+    // If valid index provided, pin at that position
+    if (index >= 0) {
+      await this._pinSiteAt(site, index);
+      this._broadcastPinnedSitesUpdated();
+    } else {
+      // Bug 1458658. If the top site is being pinned from an 'Add a Top Site' option,
+      // then we want to make sure to unblock that link if it has previously been
+      // blocked. We know if the site has been added because the index will be -1.
+      if (index === -1) {
+        lazy.NewTabUtils.blockedLinks.unblock({ url: site.url });
+        this.frecentCache.expire();
+      }
+      this.insert(action);
+    }
+  }
+
+  /**
+   * Handle an unpin action of a site.
+   */
+  unpin(action) {
+    const { site } = action.data;
+    lazy.NewTabUtils.pinnedLinks.unpin(site);
+    this._broadcastPinnedSitesUpdated();
+  }
+
+  unpinAllSearchShortcuts() {
+    Services.prefs.clearUserPref(
+      `browser.newtabpage.activity-stream.${SEARCH_SHORTCUTS_HAVE_PINNED_PREF}`
+    );
+    for (let pinnedLink of lazy.NewTabUtils.pinnedLinks.links) {
+      if (pinnedLink && pinnedLink.searchTopSite) {
+        lazy.NewTabUtils.pinnedLinks.unpin(pinnedLink);
+      }
+    }
+    this.pinnedCache.expire();
+  }
+
+  _unpinSearchShortcut(vendor) {
+    for (let pinnedLink of lazy.NewTabUtils.pinnedLinks.links) {
+      if (
+        pinnedLink &&
+        pinnedLink.searchTopSite &&
+        shortURL(pinnedLink) === vendor
+      ) {
+        lazy.NewTabUtils.pinnedLinks.unpin(pinnedLink);
+        this.pinnedCache.expire();
+
+        const prevInsertedShortcuts = this.store
+          .getState()
+          .Prefs.values[SEARCH_SHORTCUTS_HAVE_PINNED_PREF].split(",");
+        this.store.dispatch(
+          ac.SetPref(
+            SEARCH_SHORTCUTS_HAVE_PINNED_PREF,
+            prevInsertedShortcuts.filter(s => s !== vendor).join(",")
+          )
+        );
+        break;
+      }
+    }
+  }
+
+  /**
+   * Reduces the given pinning index by the number of preceding sponsored
+   * sites, to accomodate for sponsored sites pushing pinned ones to the side,
+   * effectively increasing their index again.
+   */
+  _adjustPinIndexForSponsoredLinks(site, index) {
+    if (!this._linksWithDefaults) {
+      return index;
+    }
+    // Adjust insertion index for sponsored sites since their position is
+    // fixed.
+    let adjustedIndex = index;
+    for (let i = 0; i < index; i++) {
+      const link = this._linksWithDefaults[i];
+      if (
+        link &&
+        link.sponsored_position &&
+        this._linksWithDefaults[i]?.url !== site.url
+      ) {
+        adjustedIndex--;
+      }
+    }
+    return adjustedIndex;
+  }
+
+  /**
+   * Insert a site to pin at a position shifting over any other pinned sites.
+   */
+  _insertPin(site, originalIndex, draggedFromIndex) {
+    let index = this._adjustPinIndexForSponsoredLinks(site, originalIndex);
+
+    // Don't insert any pins past the end of the visible top sites. Otherwise,
+    // we can end up with a bunch of pinned sites that can never be unpinned again
+    // from the UI.
+    const topSitesCount =
+      this.store.getState().Prefs.values[ROWS_PREF] *
+      TOP_SITES_MAX_SITES_PER_ROW;
+    if (index >= topSitesCount) {
+      return;
+    }
+
+    let pinned = lazy.NewTabUtils.pinnedLinks.links;
+    if (!pinned[index]) {
+      this._pinSiteAt(site, index);
+    } else {
+      pinned[draggedFromIndex] = null;
+      // Find the hole to shift the pinned site(s) towards. We shift towards the
+      // hole left by the site being dragged.
+      let holeIndex = index;
+      const indexStep = index > draggedFromIndex ? -1 : 1;
+      while (pinned[holeIndex]) {
+        holeIndex += indexStep;
+      }
+      if (holeIndex >= topSitesCount || holeIndex < 0) {
+        // There are no holes, so we will effectively unpin the last slot and shifting
+        // towards it. This only happens when adding a new top site to an already
+        // fully pinned grid.
+        holeIndex = topSitesCount - 1;
+      }
+
+      // Shift towards the hole.
+      const shiftingStep = holeIndex > index ? -1 : 1;
+      while (holeIndex !== index) {
+        const nextIndex = holeIndex + shiftingStep;
+        this._pinSiteAt(pinned[nextIndex], holeIndex);
+        holeIndex = nextIndex;
+      }
+      this._pinSiteAt(site, index);
+    }
+  }
+
+  /**
+   * Handle an insert (drop/add) action of a site.
+   */
+  async insert(action) {
+    let { index } = action.data;
+    // Treat invalid pin index values (e.g., -1, undefined) as insert in the first position
+    if (!(index > 0)) {
+      index = 0;
+    }
+
+    // Inserting a top site pins it in the specified slot, pushing over any link already
+    // pinned in the slot (unless it's the last slot, then it replaces).
+    this._insertPin(
+      action.data.site,
+      index,
+      action.data.draggedFromIndex !== undefined
+        ? action.data.draggedFromIndex
+        : this.store.getState().Prefs.values[ROWS_PREF] *
+            TOP_SITES_MAX_SITES_PER_ROW
+    );
+
+    await this._clearLinkCustomScreenshot(action.data.site);
+    this._broadcastPinnedSitesUpdated();
+  }
+
+  updatePinnedSearchShortcuts({ addedShortcuts, deletedShortcuts }) {
+    // Unpin the deletedShortcuts.
+    deletedShortcuts.forEach(({ url }) => {
+      lazy.NewTabUtils.pinnedLinks.unpin({ url });
+    });
+
+    // Pin the addedShortcuts.
+    const numberOfSlots =
+      this.store.getState().Prefs.values[ROWS_PREF] *
+      TOP_SITES_MAX_SITES_PER_ROW;
+    addedShortcuts.forEach(shortcut => {
+      // Find first hole in pinnedLinks.
+      let index = lazy.NewTabUtils.pinnedLinks.links.findIndex(link => !link);
+      if (
+        index < 0 &&
+        lazy.NewTabUtils.pinnedLinks.links.length + 1 < numberOfSlots
+      ) {
+        // pinnedLinks can have less slots than the total available.
+        index = lazy.NewTabUtils.pinnedLinks.links.length;
+      }
+      if (index >= 0) {
+        lazy.NewTabUtils.pinnedLinks.pin(shortcut, index);
+      } else {
+        // No slots available, we need to do an insert in first slot and push over other pinned links.
+        this._insertPin(shortcut, 0, numberOfSlots);
+      }
+    });
+
+    this._broadcastPinnedSitesUpdated();
+  }
+
+  onAction(action) {
+    switch (action.type) {
+      case at.INIT:
+        this.init();
+        this.updateCustomSearchShortcuts(true /* isStartup */);
+        break;
+      case at.SYSTEM_TICK:
+        this.refresh({ broadcast: false });
+        this._contile.periodicUpdate();
+        break;
+      // All these actions mean we need new top sites
+      case at.PLACES_HISTORY_CLEARED:
+      case at.PLACES_LINKS_DELETED:
+        this.frecentCache.expire();
+        this.refresh({ broadcast: true });
+        break;
+      case at.PLACES_LINKS_CHANGED:
+        this.frecentCache.expire();
+        this.refresh({ broadcast: false });
+        break;
+      case at.PLACES_LINK_BLOCKED:
+        this.frecentCache.expire();
+        this.pinnedCache.expire();
+        this.refresh({ broadcast: true });
+        break;
+      case at.PREF_CHANGED:
+        switch (action.data.name) {
+          case DEFAULT_SITES_PREF:
+            if (!this._useRemoteSetting) {
+              this.refreshDefaults(action.data.value);
+            }
+            break;
+          case ROWS_PREF:
+          case FILTER_DEFAULT_SEARCH_PREF:
+          case SEARCH_SHORTCUTS_SEARCH_ENGINES_PREF:
+            this.refresh({ broadcast: true });
+            break;
+          case SHOW_SPONSORED_PREF:
+            if (
+              lazy.NimbusFeatures.newtab.getVariable(
+                NIMBUS_VARIABLE_CONTILE_ENABLED
+              )
+            ) {
+              this._contile.refresh();
+            } else {
+              this.refresh({ broadcast: true });
+            }
+            if (!action.data.value) {
+              this._contile._resetContileCachePrefs();
+            }
+
+            break;
+          case SEARCH_SHORTCUTS_EXPERIMENT:
+            if (action.data.value) {
+              this.updateCustomSearchShortcuts();
+            } else {
+              this.unpinAllSearchShortcuts();
+            }
+            this.refresh({ broadcast: true });
+        }
+        break;
+      case at.UPDATE_SECTION_PREFS:
+        if (action.data.id === SECTION_ID) {
+          this.updateSectionPrefs(action.data.value);
+        }
+        break;
+      case at.PREFS_INITIAL_VALUES:
+        if (!this._useRemoteSetting) {
+          this.refreshDefaults(action.data[DEFAULT_SITES_PREF]);
+        }
+        break;
+      case at.TOP_SITES_PIN:
+        this.pin(action);
+        break;
+      case at.TOP_SITES_UNPIN:
+        this.unpin(action);
+        break;
+      case at.TOP_SITES_INSERT:
+        this.insert(action);
+        break;
+      case at.PREVIEW_REQUEST:
+        this.getScreenshotPreview(action.data.url, action.meta.fromTarget);
+        break;
+      case at.UPDATE_PINNED_SEARCH_SHORTCUTS:
+        this.updatePinnedSearchShortcuts(action.data);
+        break;
+      case at.DISCOVERY_STREAM_SPOCS_UPDATE:
+        // Refresh to update sponsored topsites.
+        this.refresh({ broadcast: true, isStartup: action.meta.isStartup });
+        break;
+      case at.UNINIT:
+        this.uninit();
+        break;
+    }
+  }
+}
+
+export const TopSites = new _TopSites();
diff --git a/browser/components/topsites/moz.build b/browser/components/topsites/moz.build
new file mode 100644
index 0000000000..f8c7a96fa2
--- /dev/null
+++ b/browser/components/topsites/moz.build
@@ -0,0 +1,12 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+EXTRA_JS_MODULES += ["TopSites.sys.mjs"]
+
+XPCSHELL_TESTS_MANIFESTS += ["test/unit/xpcshell.toml"]
+
+with Files("**"):
+    BUG_COMPONENT = ("Firefox", "Top Sites")
diff --git a/browser/components/topsites/test/unit/test_top_sites.js b/browser/components/topsites/test/unit/test_top_sites.js
new file mode 100644
index 0000000000..3de5f43262
--- /dev/null
+++ b/browser/components/topsites/test/unit/test_top_sites.js
@@ -0,0 +1,3571 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { TopSites, DEFAULT_TOP_SITES } = ChromeUtils.importESModule(
+  "resource:///modules/TopSites.sys.mjs"
+);
+
+const { actionCreators: ac, actionTypes: at } = ChromeUtils.importESModule(
+  "resource://activity-stream/common/Actions.mjs"
+);
+
+ChromeUtils.defineESModuleGetters(this, {
+  FilterAdult: "resource://activity-stream/lib/FilterAdult.sys.mjs",
+  NewTabUtils: "resource://gre/modules/NewTabUtils.sys.mjs",
+  NimbusFeatures: "resource://nimbus/ExperimentAPI.sys.mjs",
+  PageThumbs: "resource://gre/modules/PageThumbs.sys.mjs",
+  shortURL: "resource://activity-stream/lib/ShortURL.sys.mjs",
+  sinon: "resource://testing-common/Sinon.sys.mjs",
+  Screenshots: "resource://activity-stream/lib/Screenshots.sys.mjs",
+  Sampling: "resource://gre/modules/components-utils/Sampling.sys.mjs",
+  SearchService: "resource://gre/modules/SearchService.sys.mjs",
+  TestUtils: "resource://testing-common/TestUtils.sys.mjs",
+  TOP_SITES_DEFAULT_ROWS: "resource://activity-stream/common/Reducers.sys.mjs",
+  TOP_SITES_MAX_SITES_PER_ROW:
+    "resource://activity-stream/common/Reducers.sys.mjs",
+});
+
+const FAKE_FAVICON = "data987";
+const FAKE_FAVICON_SIZE = 128;
+const FAKE_FRECENCY = 200;
+const FAKE_LINKS = new Array(2 * TOP_SITES_MAX_SITES_PER_ROW)
+  .fill(null)
+  .map((v, i) => ({
+    frecency: FAKE_FRECENCY,
+    url: `http://www.site${i}.com`,
+  }));
+const FAKE_SCREENSHOT = "data123";
+const SEARCH_SHORTCUTS_EXPERIMENT_PREF = "improvesearch.topSiteSearchShortcuts";
+const SEARCH_SHORTCUTS_SEARCH_ENGINES_PREF =
+  "improvesearch.topSiteSearchShortcuts.searchEngines";
+const SEARCH_SHORTCUTS_HAVE_PINNED_PREF =
+  "improvesearch.topSiteSearchShortcuts.havePinned";
+const SHOWN_ON_NEWTAB_PREF = "feeds.topsites";
+const SHOW_SPONSORED_PREF = "showSponsoredTopSites";
+const TOP_SITES_BLOCKED_SPONSORS_PREF = "browser.topsites.blockedSponsors";
+const CONTILE_CACHE_PREF = "browser.topsites.contile.cachedTiles";
+
+// This pref controls how long the contile cache is valid for in seconds.
+const CONTILE_CACHE_VALID_FOR_SECONDS_PREF =
+  "browser.topsites.contile.cacheValidFor";
+// This pref records when the last contile fetch occurred, as a UNIX timestamp
+// in seconds.
+const CONTILE_CACHE_LAST_FETCH_PREF = "browser.topsites.contile.lastFetch";
+
+function FakeTippyTopProvider() {}
+FakeTippyTopProvider.prototype = {
+  async init() {
+    this.initialized = true;
+  },
+  processSite(site) {
+    return site;
+  },
+};
+
+let gSearchServiceInitStub;
+let gGetTopSitesStub;
+
+function stubTopSites(sandbox) {
+  let cachedStorage = TopSites._storage;
+  let cachedStore = TopSites.store;
+
+  async function cleanup() {
+    if (TopSites._refreshing) {
+      info("Wait for refresh to finish.");
+      // Wait for refresh to finish or else removing the store while a process
+      // is running will result in errors.
+      await TestUtils.topicObserved("topsites-refreshed");
+    }
+    TopSites._tippyTopProvider.initialized = false;
+    TopSites._storage = cachedStorage;
+    TopSites.store = cachedStore;
+    TopSites.pinnedCache.clear();
+    TopSites.frecentCache.clear();
+    info("Finished cleaning up TopSites.");
+  }
+
+  const storage = {
+    init: sandbox.stub().resolves(),
+    get: sandbox.stub().resolves(),
+    set: sandbox.stub().resolves(),
+  };
+
+  // Setup for tests that don't call `init` but require feed.storage
+  TopSites._storage = storage;
+  TopSites.store = {
+    dispatch: sinon.spy(),
+    getState() {
+      return this.state;
+    },
+    state: {
+      Prefs: { values: { topSitesRows: 2 } },
+      TopSites: { rows: Array(12).fill("site") },
+    },
+    dbStorage: { getDbTable: sandbox.stub().returns(storage) },
+  };
+  info("Created mock store for TopSites.");
+  return cleanup;
+}
+
+add_setup(async () => {
+  let sandbox = sinon.createSandbox();
+  sandbox.stub(SearchService.prototype, "defaultEngine").get(() => {
+    return { identifier: "ddg", searchForm: "https://duckduckgo.com" };
+  });
+
+  gGetTopSitesStub = sandbox
+    .stub(NewTabUtils.activityStreamLinks, "getTopSites")
+    .resolves(FAKE_LINKS);
+
+  gSearchServiceInitStub = sandbox
+    .stub(SearchService.prototype, "init")
+    .resolves();
+
+  sandbox.stub(NewTabUtils.activityStreamProvider, "_faviconBytesToDataURI");
+
+  sandbox
+    .stub(NewTabUtils.activityStreamProvider, "_addFavicons")
+    .callsFake(l => {
+      return Promise.resolve(
+        l.map(link => {
+          link.favicon = FAKE_FAVICON;
+          link.faviconSize = FAKE_FAVICON_SIZE;
+          return link;
+        })
+      );
+    });
+
+  sandbox.stub(Screenshots, "getScreenshotForURL").resolves(FAKE_SCREENSHOT);
+  sandbox.spy(Screenshots, "maybeCacheScreenshot");
+  sandbox.stub(Screenshots, "_shouldGetScreenshots").returns(true);
+
+  registerCleanupFunction(() => {
+    sandbox.restore();
+  });
+});
+
+add_task(async function test_construction() {
+  Assert.ok(TopSites._currentSearchHostname, "_currentSearchHostname defined");
+});
+
+add_task(async function test_refreshDefaults() {
+  let sandbox = sinon.createSandbox();
+  let cleanup = stubTopSites(sandbox);
+  Assert.ok(
+    !DEFAULT_TOP_SITES.length,
+    "Should have 0 DEFAULT_TOP_SITES initially."
+  );
+
+  info("refreshDefaults should add defaults on PREFS_INITIAL_VALUES");
+  TopSites.onAction({
+    type: at.PREFS_INITIAL_VALUES,
+    data: { "default.sites": "https://foo.com" },
+  });
+
+  Assert.equal(
+    DEFAULT_TOP_SITES.length,
+    1,
+    "Should have 1 DEFAULT_TOP_SITES now."
+  );
+
+  // Reset the DEFAULT_TOP_SITES;
+  DEFAULT_TOP_SITES.length = 0;
+
+  info("refreshDefaults should add defaults on default.sites PREF_CHANGED");
+  TopSites.onAction({
+    type: at.PREF_CHANGED,
+    data: { name: "default.sites", value: "https://foo.com" },
+  });
+
+  Assert.equal(
+    DEFAULT_TOP_SITES.length,
+    1,
+    "Should have 1 DEFAULT_TOP_SITES now."
+  );
+
+  // Reset the DEFAULT_TOP_SITES;
+  DEFAULT_TOP_SITES.length = 0;
+
+  info("refreshDefaults should refresh on topSiteRows PREF_CHANGED");
+  let refreshStub = sandbox.stub(TopSites, "refresh");
+  TopSites.onAction({ type: at.PREF_CHANGED, data: { name: "topSitesRows" } });
+  Assert.ok(TopSites.refresh.calledOnce, "refresh called");
+  refreshStub.restore();
+
+  // Reset the DEFAULT_TOP_SITES;
+  DEFAULT_TOP_SITES.length = 0;
+
+  info("refreshDefaults should have default sites with .isDefault = true");
+  TopSites.refreshDefaults("https://foo.com");
+  Assert.equal(
+    DEFAULT_TOP_SITES.length,
+    1,
+    "Should have a DEFAULT_TOP_SITES now."
+  );
+  Assert.ok(
+    DEFAULT_TOP_SITES[0].isDefault,
+    "Lone top site should be the default."
+  );
+
+  // Reset the DEFAULT_TOP_SITES;
+  DEFAULT_TOP_SITES.length = 0;
+
+  info("refreshDefaults should have default sites with appropriate hostname");
+  TopSites.refreshDefaults("https://foo.com");
+  Assert.equal(
+    DEFAULT_TOP_SITES.length,
+    1,
+    "Should have a DEFAULT_TOP_SITES now."
+  );
+  let [site] = DEFAULT_TOP_SITES;
+  Assert.equal(
+    site.hostname,
+    shortURL(site),
+    "Lone top site should have the right hostname."
+  );
+
+  // Reset the DEFAULT_TOP_SITES;
+  DEFAULT_TOP_SITES.length = 0;
+
+  info("refreshDefaults should add no defaults on empty pref");
+  TopSites.refreshDefaults("");
+  Assert.equal(
+    DEFAULT_TOP_SITES.length,
+    0,
+    "Should have 0 DEFAULT_TOP_SITES now."
+  );
+
+  info("refreshDefaults should be able to clear defaults");
+  TopSites.refreshDefaults("https://foo.com");
+  TopSites.refreshDefaults("");
+
+  Assert.equal(
+    DEFAULT_TOP_SITES.length,
+    0,
+    "Should have 0 DEFAULT_TOP_SITES now."
+  );
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_filterForThumbnailExpiration() {
+  let sandbox = sinon.createSandbox();
+  let cleanup = stubTopSites(sandbox);
+
+  info(
+    "filterForThumbnailExpiration should pass rows.urls to the callback provided"
+  );
+  const rows = [
+    { url: "foo.com" },
+    { url: "bar.com", customScreenshotURL: "custom" },
+  ];
+  TopSites.store.state.TopSites = { rows };
+  const stub = sandbox.stub();
+  TopSites.filterForThumbnailExpiration(stub);
+  Assert.ok(stub.calledOnce);
+  Assert.ok(stub.calledWithExactly(["foo.com", "bar.com", "custom"]));
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(
+  async function test_getLinksWithDefaults_on_SearchService_init_failure() {
+    let sandbox = sinon.createSandbox();
+    let cleanup = stubTopSites(sandbox);
+
+    TopSites.refreshDefaults("https://foo.com");
+
+    gSearchServiceInitStub.rejects(
+      new Error("Simulating search init failures")
+    );
+
+    const result = await TopSites.getLinksWithDefaults();
+    Assert.ok(result);
+
+    gSearchServiceInitStub.resolves();
+
+    sandbox.restore();
+    await cleanup();
+  }
+);
+
+add_task(async function test_getLinksWithDefaults() {
+  NewTabUtils.activityStreamLinks.getTopSites.resetHistory();
+
+  let sandbox = sinon.createSandbox();
+  let cleanup = stubTopSites(sandbox);
+
+  TopSites.refreshDefaults("https://foo.com");
+
+  info("getLinksWithDefaults should get the links from NewTabUtils");
+  let result = await TopSites.getLinksWithDefaults();
+
+  const reference = FAKE_LINKS.map(site =>
+    Object.assign({}, site, {
+      hostname: shortURL(site),
+      typedBonus: true,
+    })
+  );
+
+  Assert.deepEqual(result, reference);
+  Assert.ok(NewTabUtils.activityStreamLinks.getTopSites.calledOnce);
+
+  info("getLinksWithDefaults should indicate the links get typed bonus");
+  Assert.ok(result[0].typedBonus, "Expected typed bonus property to be true.");
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_filterAdult() {
+  let sandbox = sinon.createSandbox();
+  info("getLinksWithDefaults should filter out non-pinned adult sites");
+
+  sandbox.stub(FilterAdult, "filter").returns([]);
+  const TEST_URL = "https://foo.com/";
+  sandbox.stub(NewTabUtils.pinnedLinks, "links").get(() => [{ url: TEST_URL }]);
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  const result = await TopSites.getLinksWithDefaults();
+  Assert.ok(FilterAdult.filter.calledOnce);
+  Assert.equal(result.length, 1);
+  Assert.equal(result[0].url, TEST_URL);
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_caching() {
+  let sandbox = sinon.createSandbox();
+
+  info(
+    "getLinksWithDefaults should filter out the defaults that have been blocked"
+  );
+  // make sure we only have one top site, and we block the only default site we have to show
+  const url = "www.myonlytopsite.com";
+  const topsite = {
+    frecency: FAKE_FRECENCY,
+    hostname: shortURL({ url }),
+    typedBonus: true,
+    url,
+  };
+
+  const blockedDefaultSite = { url: "https://foo.com" };
+  gGetTopSitesStub.resolves([topsite]);
+  sandbox.stub(NewTabUtils.blockedLinks, "isBlocked").callsFake(site => {
+    return site.url === blockedDefaultSite.url;
+  });
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+  const result = await TopSites.getLinksWithDefaults();
+
+  // what we should be left with is just the top site we added, and not the default site we blocked
+  Assert.equal(result.length, 1);
+  Assert.deepEqual(result[0], topsite);
+  let foundBlocked = result.find(site => site.url === blockedDefaultSite.url);
+  Assert.ok(!foundBlocked, "Should not have found blocked site.");
+
+  gGetTopSitesStub.resolves(FAKE_LINKS);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_dedupe() {
+  let sandbox = sinon.createSandbox();
+
+  info("getLinksWithDefaults should call dedupe.group on the links");
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  let stub = sandbox.stub(TopSites.dedupe, "group").callsFake((...id) => id);
+  await TopSites.getLinksWithDefaults();
+
+  Assert.ok(stub.calledOnce, "dedupe.group was called once");
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test__dedupe_key() {
+  let sandbox = sinon.createSandbox();
+
+  info("_dedupeKey should dedupe on hostname instead of url");
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  let site = { url: "foo", hostname: "bar" };
+  let result = TopSites._dedupeKey(site);
+
+  Assert.equal(result, site.hostname, "deduped on hostname");
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_adds_defaults() {
+  let sandbox = sinon.createSandbox();
+
+  info(
+    "getLinksWithDefaults should add defaults if there are are not enough links"
+  );
+  const TEST_LINKS = [{ frecency: FAKE_FRECENCY, url: "foo.com" }];
+  gGetTopSitesStub.resolves(TEST_LINKS);
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  let result = await TopSites.getLinksWithDefaults();
+
+  let reference = [...TEST_LINKS, ...DEFAULT_TOP_SITES].map(s =>
+    Object.assign({}, s, {
+      hostname: shortURL(s),
+      typedBonus: true,
+    })
+  );
+
+  Assert.deepEqual(result, reference);
+
+  gGetTopSitesStub.resolves(FAKE_LINKS);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(
+  async function test_getLinksWithDefaults_adds_defaults_for_visible_slots() {
+    let sandbox = sinon.createSandbox();
+
+    info(
+      "getLinksWithDefaults should only add defaults up to the number of visible slots"
+    );
+    const numVisible = TOP_SITES_DEFAULT_ROWS * TOP_SITES_MAX_SITES_PER_ROW;
+    let testLinks = [];
+    for (let i = 0; i < numVisible - 1; i++) {
+      testLinks.push({ frecency: FAKE_FRECENCY, url: `foo${i}.com` });
+    }
+    gGetTopSitesStub.resolves(testLinks);
+
+    let cleanup = stubTopSites(sandbox);
+    TopSites.refreshDefaults("https://foo.com");
+
+    let result = await TopSites.getLinksWithDefaults();
+
+    let reference = [...testLinks, DEFAULT_TOP_SITES[0]].map(s =>
+      Object.assign({}, s, {
+        hostname: shortURL(s),
+        typedBonus: true,
+      })
+    );
+
+    Assert.equal(result.length, numVisible);
+    Assert.deepEqual(result, reference);
+
+    gGetTopSitesStub.resolves(FAKE_LINKS);
+    sandbox.restore();
+    await cleanup();
+  }
+);
+
+add_task(async function test_getLinksWithDefaults_no_throw_on_no_links() {
+  let sandbox = sinon.createSandbox();
+
+  info("getLinksWithDefaults should not throw if NewTabUtils returns null");
+  gGetTopSitesStub.resolves(null);
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  await TopSites.getLinksWithDefaults();
+  Assert.ok(true, "getLinksWithDefaults did not throw");
+
+  gGetTopSitesStub.resolves(FAKE_LINKS);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_get_more_on_request() {
+  let sandbox = sinon.createSandbox();
+
+  info("getLinksWithDefaults should get more if the user has asked for more");
+  let testLinks = new Array(4 * TOP_SITES_MAX_SITES_PER_ROW)
+    .fill(null)
+    .map((v, i) => ({
+      frecency: FAKE_FRECENCY,
+      url: `http://www.site${i}.com`,
+    }));
+  gGetTopSitesStub.resolves(testLinks);
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  const TEST_ROWS = 3;
+  TopSites.store.state.Prefs.values.topSitesRows = TEST_ROWS;
+
+  let result = await TopSites.getLinksWithDefaults();
+  Assert.equal(result.length, TEST_ROWS * TOP_SITES_MAX_SITES_PER_ROW);
+
+  gGetTopSitesStub.resolves(FAKE_LINKS);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_reuse_cache() {
+  let sandbox = sinon.createSandbox();
+  info("getLinksWithDefaults should reuse the cache on subsequent calls");
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  gGetTopSitesStub.resetHistory();
+
+  await TopSites.getLinksWithDefaults();
+  await TopSites.getLinksWithDefaults();
+
+  Assert.ok(
+    NewTabUtils.activityStreamLinks.getTopSites.calledOnce,
+    "getTopSites only called once"
+  );
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(
+  async function test_getLinksWithDefaults_ignore_cache_on_requesting_more() {
+    let sandbox = sinon.createSandbox();
+    info("getLinksWithDefaults should ignore the cache when requesting more");
+
+    let cleanup = stubTopSites(sandbox);
+    TopSites.refreshDefaults("https://foo.com");
+
+    gGetTopSitesStub.resetHistory();
+
+    await TopSites.getLinksWithDefaults();
+    TopSites.store.state.Prefs.values.topSitesRows *= 3;
+    await TopSites.getLinksWithDefaults();
+
+    Assert.ok(
+      NewTabUtils.activityStreamLinks.getTopSites.calledTwice,
+      "getTopSites called twice"
+    );
+
+    sandbox.restore();
+    await cleanup();
+  }
+);
+
+add_task(
+  async function test_getLinksWithDefaults_migrate_frecent_screenshot_data() {
+    let sandbox = sinon.createSandbox();
+    info(
+      "getLinksWithDefaults should migrate frecent screenshot data without getting screenshots again"
+    );
+
+    let cleanup = stubTopSites(sandbox);
+    TopSites.refreshDefaults("https://foo.com");
+
+    gGetTopSitesStub.resetHistory();
+
+    TopSites.store.state.Prefs.values[SHOWN_ON_NEWTAB_PREF] = true;
+    await TopSites.getLinksWithDefaults();
+
+    let originalCallCount = Screenshots.getScreenshotForURL.callCount;
+    TopSites.frecentCache.expire();
+
+    let result = await TopSites.getLinksWithDefaults();
+
+    Assert.ok(
+      NewTabUtils.activityStreamLinks.getTopSites.calledTwice,
+      "getTopSites called twice"
+    );
+    Assert.equal(
+      Screenshots.getScreenshotForURL.callCount,
+      originalCallCount,
+      "getScreenshotForURL was not called again."
+    );
+    Assert.equal(result[0].screenshot, FAKE_SCREENSHOT);
+
+    sandbox.restore();
+    await cleanup();
+  }
+);
+
+add_task(
+  async function test_getLinksWithDefaults_migrate_pinned_favicon_data() {
+    let sandbox = sinon.createSandbox();
+    info(
+      "getLinksWithDefaults should migrate pinned favicon data without getting favicons again"
+    );
+
+    let cleanup = stubTopSites(sandbox);
+    TopSites.refreshDefaults("https://foo.com");
+
+    gGetTopSitesStub.resetHistory();
+
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [{ url: "https://foo.com/" }]);
+
+    await TopSites.getLinksWithDefaults();
+
+    let originalCallCount =
+      NewTabUtils.activityStreamProvider._addFavicons.callCount;
+    TopSites.pinnedCache.expire();
+
+    let result = await TopSites.getLinksWithDefaults();
+
+    Assert.equal(
+      NewTabUtils.activityStreamProvider._addFavicons.callCount,
+      originalCallCount,
+      "_addFavicons was not called again."
+    );
+    Assert.equal(result[0].favicon, FAKE_FAVICON);
+    Assert.equal(result[0].faviconSize, FAKE_FAVICON_SIZE);
+
+    sandbox.restore();
+    await cleanup();
+  }
+);
+
+add_task(async function test_getLinksWithDefaults_no_internal_properties() {
+  let sandbox = sinon.createSandbox();
+  info("getLinksWithDefaults should not expose internal link properties");
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  let result = await TopSites.getLinksWithDefaults();
+
+  let internal = Object.keys(result[0]).filter(key => key.startsWith("__"));
+  Assert.equal(internal.join(""), "");
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_copy_frecent_screenshot() {
+  let sandbox = sinon.createSandbox();
+  info(
+    "getLinksWithDefaults should copy the screenshot of the frecent site if " +
+      "pinned site doesn't have customScreenshotURL"
+  );
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  const TEST_SCREENSHOT = "screenshot";
+
+  gGetTopSitesStub.resolves([
+    { url: "https://foo.com/", screenshot: TEST_SCREENSHOT },
+  ]);
+  sandbox
+    .stub(NewTabUtils.pinnedLinks, "links")
+    .get(() => [{ url: "https://foo.com/" }]);
+
+  let result = await TopSites.getLinksWithDefaults();
+
+  Assert.equal(result[0].screenshot, TEST_SCREENSHOT);
+
+  gGetTopSitesStub.resolves(FAKE_LINKS);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_no_copy_frecent_screenshot() {
+  let sandbox = sinon.createSandbox();
+  info(
+    "getLinksWithDefaults should not copy the frecent screenshot if " +
+      "customScreenshotURL is set"
+  );
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  gGetTopSitesStub.resolves([
+    { url: "https://foo.com/", screenshot: "screenshot" },
+  ]);
+  sandbox
+    .stub(NewTabUtils.pinnedLinks, "links")
+    .get(() => [{ url: "https://foo.com/", customScreenshotURL: "custom" }]);
+
+  let result = await TopSites.getLinksWithDefaults();
+
+  Assert.equal(result[0].screenshot, undefined);
+
+  gGetTopSitesStub.resolves(FAKE_LINKS);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_persist_screenshot() {
+  let sandbox = sinon.createSandbox();
+  info(
+    "getLinksWithDefaults should keep the same screenshot if no frecent site is found"
+  );
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  const CUSTOM_SCREENSHOT = "custom";
+
+  gGetTopSitesStub.resolves([]);
+  sandbox
+    .stub(NewTabUtils.pinnedLinks, "links")
+    .get(() => [{ url: "https://foo.com/", screenshot: CUSTOM_SCREENSHOT }]);
+
+  let result = await TopSites.getLinksWithDefaults();
+
+  Assert.equal(result[0].screenshot, CUSTOM_SCREENSHOT);
+
+  gGetTopSitesStub.resolves(FAKE_LINKS);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(
+  async function test_getLinksWithDefaults_no_overwrite_pinned_screenshot() {
+    let sandbox = sinon.createSandbox();
+    info("getLinksWithDefaults should not overwrite pinned site screenshot");
+
+    let cleanup = stubTopSites(sandbox);
+    TopSites.refreshDefaults("https://foo.com");
+
+    const EXISTING_SCREENSHOT = "some-screenshot";
+
+    gGetTopSitesStub.resolves([{ url: "https://foo.com/", screenshot: "foo" }]);
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [
+        { url: "https://foo.com/", screenshot: EXISTING_SCREENSHOT },
+      ]);
+
+    let result = await TopSites.getLinksWithDefaults();
+
+    Assert.equal(result[0].screenshot, EXISTING_SCREENSHOT);
+
+    gGetTopSitesStub.resolves(FAKE_LINKS);
+    sandbox.restore();
+    await cleanup();
+  }
+);
+
+add_task(
+  async function test_getLinksWithDefaults_no_searchTopSite_from_frecent() {
+    let sandbox = sinon.createSandbox();
+    info("getLinksWithDefaults should not set searchTopSite from frecent site");
+
+    let cleanup = stubTopSites(sandbox);
+    TopSites.refreshDefaults("https://foo.com");
+
+    const EXISTING_SCREENSHOT = "some-screenshot";
+
+    gGetTopSitesStub.resolves([
+      {
+        url: "https://foo.com/",
+        searchTopSite: true,
+        screenshot: EXISTING_SCREENSHOT,
+      },
+    ]);
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [{ url: "https://foo.com/" }]);
+
+    let result = await TopSites.getLinksWithDefaults();
+
+    Assert.ok(!result[0].searchTopSite);
+    // But it should copy over other properties
+    Assert.equal(result[0].screenshot, EXISTING_SCREENSHOT);
+
+    gGetTopSitesStub.resolves(FAKE_LINKS);
+    sandbox.restore();
+    await cleanup();
+  }
+);
+
+add_task(async function test_getLinksWithDefaults_concurrency_getTopSites() {
+  let sandbox = sinon.createSandbox();
+  info(
+    "getLinksWithDefaults concurrent calls should call the backing data once"
+  );
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  NewTabUtils.activityStreamLinks.getTopSites.resetHistory();
+
+  await Promise.all([
+    TopSites.getLinksWithDefaults(),
+    TopSites.getLinksWithDefaults(),
+  ]);
+
+  Assert.ok(
+    NewTabUtils.activityStreamLinks.getTopSites.calledOnce,
+    "getTopSites only called once"
+  );
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(
+  async function test_getLinksWithDefaults_concurrency_getScreenshotForURL() {
+    let sandbox = sinon.createSandbox();
+    info(
+      "getLinksWithDefaults concurrent calls should call the backing data once"
+    );
+
+    let cleanup = stubTopSites(sandbox);
+    TopSites.refreshDefaults("https://foo.com");
+    TopSites.store.state.Prefs.values[SHOWN_ON_NEWTAB_PREF] = true;
+
+    NewTabUtils.activityStreamLinks.getTopSites.resetHistory();
+    Screenshots.getScreenshotForURL.resetHistory();
+
+    await Promise.all([
+      TopSites.getLinksWithDefaults(),
+      TopSites.getLinksWithDefaults(),
+    ]);
+
+    Assert.ok(
+      NewTabUtils.activityStreamLinks.getTopSites.calledOnce,
+      "getTopSites only called once"
+    );
+
+    Assert.equal(
+      Screenshots.getScreenshotForURL.callCount,
+      FAKE_LINKS.length,
+      "getLinksWithDefaults concurrent calls should get screenshots once per link"
+    );
+    await cleanup();
+
+    cleanup = stubTopSites(sandbox);
+    TopSites.store.state.Prefs.values[SHOWN_ON_NEWTAB_PREF] = true;
+
+    TopSites.refreshDefaults("https://foo.com");
+
+    sandbox.stub(TopSites, "_requestRichIcon");
+    await Promise.all([
+      TopSites.getLinksWithDefaults(),
+      TopSites.getLinksWithDefaults(),
+    ]);
+
+    Assert.equal(
+      TopSites.store.dispatch.callCount,
+      FAKE_LINKS.length,
+      "getLinksWithDefaults concurrent calls should dispatch once per link screenshot fetched"
+    );
+
+    sandbox.restore();
+    await cleanup();
+  }
+);
+
+add_task(async function test_getLinksWithDefaults_deduping_no_dedupe_pinned() {
+  let sandbox = sinon.createSandbox();
+  info("getLinksWithDefaults should not dedupe pinned sites");
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults("https://foo.com");
+
+  sandbox
+    .stub(NewTabUtils.pinnedLinks, "links")
+    .get(() => [
+      { url: "https://developer.mozilla.org/en-US/docs/Web" },
+      { url: "https://developer.mozilla.org/en-US/docs/Learn" },
+    ]);
+
+  let sites = await TopSites.getLinksWithDefaults();
+  Assert.equal(sites.length, 2 * TOP_SITES_MAX_SITES_PER_ROW);
+  Assert.equal(sites[0].url, NewTabUtils.pinnedLinks.links[0].url);
+  Assert.equal(sites[1].url, NewTabUtils.pinnedLinks.links[1].url);
+  Assert.equal(sites[0].hostname, sites[1].hostname);
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_prefer_pinned_sites() {
+  let sandbox = sinon.createSandbox();
+
+  info("getLinksWithDefaults should prefer pinned sites over links");
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults();
+
+  sandbox
+    .stub(NewTabUtils.pinnedLinks, "links")
+    .get(() => [
+      { url: "https://developer.mozilla.org/en-US/docs/Web" },
+      { url: "https://developer.mozilla.org/en-US/docs/Learn" },
+    ]);
+
+  const SECOND_TOP_SITE_URL = "https://www.mozilla.org/";
+
+  gGetTopSitesStub.resolves([
+    { frecency: FAKE_FRECENCY, url: "https://developer.mozilla.org/" },
+    { frecency: FAKE_FRECENCY, url: SECOND_TOP_SITE_URL },
+  ]);
+
+  let sites = await TopSites.getLinksWithDefaults();
+
+  // Expecting 3 links where there's 2 pinned and 1 www.mozilla.org, so
+  // the frecent with matching hostname as pinned is removed.
+  Assert.equal(sites.length, 3);
+  Assert.equal(sites[0].url, NewTabUtils.pinnedLinks.links[0].url);
+  Assert.equal(sites[1].url, NewTabUtils.pinnedLinks.links[1].url);
+  Assert.equal(sites[2].url, SECOND_TOP_SITE_URL);
+
+  gGetTopSitesStub.resolves(FAKE_LINKS);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_title_and_null() {
+  let sandbox = sinon.createSandbox();
+
+  info("getLinksWithDefaults should return sites that have a title");
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults();
+
+  sandbox
+    .stub(NewTabUtils.pinnedLinks, "links")
+    .get(() => [{ url: "https://github.com/mozilla/activity-stream" }]);
+
+  let sites = await TopSites.getLinksWithDefaults();
+  for (let site of sites) {
+    Assert.ok(site.hostname);
+  }
+
+  info("getLinksWithDefaults should not throw for null entries");
+  sandbox.stub(NewTabUtils.pinnedLinks, "links").get(() => [null]);
+  await TopSites.getLinksWithDefaults();
+  Assert.ok(true, "getLinksWithDefaults didn't throw");
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_calls__fetchIcon() {
+  let sandbox = sinon.createSandbox();
+
+  info("getLinksWithDefaults should return sites that have a title");
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults();
+
+  sandbox.spy(TopSites, "_fetchIcon");
+  let results = await TopSites.getLinksWithDefaults();
+  Assert.ok(results.length, "Got back some results");
+  Assert.equal(TopSites._fetchIcon.callCount, results.length);
+  for (let result of results) {
+    Assert.ok(TopSites._fetchIcon.calledWith(result));
+  }
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_calls__fetchScreenshot() {
+  let sandbox = sinon.createSandbox();
+
+  info(
+    "getLinksWithDefaults should call _fetchScreenshot when customScreenshotURL is set"
+  );
+
+  gGetTopSitesStub.resolves([]);
+  sandbox
+    .stub(NewTabUtils.pinnedLinks, "links")
+    .get(() => [{ url: "https://foo.com", customScreenshotURL: "custom" }]);
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults();
+
+  sandbox.stub(TopSites, "_fetchScreenshot");
+  await TopSites.getLinksWithDefaults();
+
+  Assert.ok(TopSites._fetchScreenshot.calledWith(sinon.match.object, "custom"));
+
+  gGetTopSitesStub.resolves(FAKE_LINKS);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getLinksWithDefaults_with_DiscoveryStream() {
+  let sandbox = sinon.createSandbox();
+  info(
+    "getLinksWithDefaults should add a sponsored topsite from discoverystream to all the valid indices"
+  );
+
+  let makeStreamData = index => ({
+    layout: [
+      {
+        components: [
+          {
+            placement: {
+              name: "sponsored-topsites",
+            },
+            spocs: {
+              positions: [{ index }],
+            },
+          },
+        ],
+      },
+    ],
+    spocs: {
+      data: {
+        "sponsored-topsites": {
+          items: [{ title: "test spoc", url: "https://test-spoc.com" }],
+        },
+      },
+    },
+  });
+
+  let cleanup = stubTopSites(sandbox);
+  TopSites.refreshDefaults();
+
+  for (let i = 0; i < FAKE_LINKS.length; i++) {
+    TopSites.store.state.DiscoveryStream = makeStreamData(i);
+    const result = await TopSites.getLinksWithDefaults();
+    const link = result[i];
+
+    Assert.equal(link.type, "SPOC");
+    Assert.equal(link.title, "test spoc");
+    Assert.equal(link.sponsored_position, i + 1);
+    Assert.equal(link.hostname, "test-spoc");
+    Assert.equal(link.url, "https://test-spoc.com");
+  }
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_init() {
+  let sandbox = sinon.createSandbox();
+
+  sandbox.stub(NimbusFeatures.newtab, "onUpdate");
+
+  let cleanup = stubTopSites(sandbox);
+
+  sandbox.stub(TopSites, "refresh");
+  await TopSites.init();
+
+  info("TopSites.init should call refresh (broadcast: true)");
+  Assert.ok(TopSites.refresh.calledOnce, "refresh called once");
+  Assert.ok(
+    TopSites.refresh.calledWithExactly({
+      broadcast: true,
+      isStartup: true,
+    })
+  );
+
+  info("TopSites.init should initialise the storage");
+  Assert.ok(
+    TopSites.store.dbStorage.getDbTable.calledOnce,
+    "getDbTable called once"
+  );
+  Assert.ok(
+    TopSites.store.dbStorage.getDbTable.calledWithExactly("sectionPrefs")
+  );
+
+  info("TopSites.init should call onUpdate to set up Nimbus update listener");
+
+  Assert.ok(
+    NimbusFeatures.newtab.onUpdate.calledOnce,
+    "NimbusFeatures.newtab.onUpdate called once"
+  );
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_refresh() {
+  let sandbox = sinon.createSandbox();
+
+  sandbox.stub(NimbusFeatures.newtab, "onUpdate");
+
+  let cleanup = stubTopSites(sandbox);
+
+  sandbox.stub(TopSites, "_fetchIcon");
+  TopSites._startedUp = true;
+
+  info("TopSites.refresh should wait for tippytop to initialize");
+  TopSites._tippyTopProvider.initialized = false;
+  sandbox.stub(TopSites._tippyTopProvider, "init").resolves();
+
+  await TopSites.refresh();
+
+  Assert.ok(
+    TopSites._tippyTopProvider.init.calledOnce,
+    "TopSites._tippyTopProvider.init called once"
+  );
+
+  info(
+    "TopSites.refresh should not init the tippyTopProvider if already initialized"
+  );
+  TopSites._tippyTopProvider.initialized = true;
+  TopSites._tippyTopProvider.init.resetHistory();
+
+  await TopSites.refresh();
+
+  Assert.ok(
+    TopSites._tippyTopProvider.init.notCalled,
+    "tippyTopProvider not initted again"
+  );
+
+  info("TopSites.refresh should broadcast TOP_SITES_UPDATED");
+  TopSites.store.dispatch.resetHistory();
+  sandbox.stub(TopSites, "getLinksWithDefaults").resolves([]);
+
+  await TopSites.refresh({ broadcast: true });
+
+  Assert.ok(TopSites.store.dispatch.calledOnce, "dispatch called once");
+  Assert.ok(
+    TopSites.store.dispatch.calledWithExactly(
+      ac.BroadcastToContent({
+        type: at.TOP_SITES_UPDATED,
+        data: { links: [], pref: { collapsed: false } },
+      })
+    )
+  );
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_refresh_dispatch() {
+  let sandbox = sinon.createSandbox();
+
+  info("TopSites.refresh should dispatch an action with the links returned");
+
+  let cleanup = stubTopSites(sandbox);
+  sandbox.stub(TopSites, "_fetchIcon");
+  TopSites._startedUp = true;
+
+  await TopSites.refresh({ broadcast: true });
+  let reference = FAKE_LINKS.map(site =>
+    Object.assign({}, site, {
+      hostname: shortURL(site),
+      typedBonus: true,
+    })
+  );
+
+  Assert.ok(TopSites.store.dispatch.calledOnce, "Store.dispatch called once");
+  Assert.equal(
+    TopSites.store.dispatch.firstCall.args[0].type,
+    at.TOP_SITES_UPDATED
+  );
+  Assert.deepEqual(
+    TopSites.store.dispatch.firstCall.args[0].data.links,
+    reference
+  );
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_refresh_empty_slots() {
+  let sandbox = sinon.createSandbox();
+
+  info(
+    "TopSites.refresh should handle empty slots in the resulting top sites array"
+  );
+
+  let cleanup = stubTopSites(sandbox);
+  sandbox.stub(TopSites, "_fetchIcon");
+  TopSites._startedUp = true;
+
+  gGetTopSitesStub.resolves([FAKE_LINKS[0]]);
+  sandbox
+    .stub(NewTabUtils.pinnedLinks, "links")
+    .get(() => [
+      null,
+      null,
+      FAKE_LINKS[1],
+      null,
+      null,
+      null,
+      null,
+      null,
+      FAKE_LINKS[2],
+    ]);
+
+  await TopSites.refresh({ broadcast: true });
+
+  Assert.ok(TopSites.store.dispatch.calledOnce, "Store.dispatch called once");
+
+  gGetTopSitesStub.resolves(FAKE_LINKS);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_refresh_to_preloaded() {
+  let sandbox = sinon.createSandbox();
+
+  info(
+    "TopSites.refresh should dispatch AlsoToPreloaded when broadcast is false"
+  );
+
+  let cleanup = stubTopSites(sandbox);
+  sandbox.stub(TopSites, "_fetchIcon");
+  TopSites._startedUp = true;
+
+  gGetTopSitesStub.resolves([]);
+  await TopSites.refresh({ broadcast: false });
+
+  Assert.ok(TopSites.store.dispatch.calledOnce, "Store.dispatch called once");
+  Assert.ok(
+    TopSites.store.dispatch.calledWithExactly(
+      ac.AlsoToPreloaded({
+        type: at.TOP_SITES_UPDATED,
+        data: { links: [], pref: { collapsed: false } },
+      })
+    )
+  );
+  gGetTopSitesStub.resolves(FAKE_LINKS);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_refresh_init_storage() {
+  let sandbox = sinon.createSandbox();
+
+  info("TopSites.refresh should not init storage of it's already initialized");
+
+  let cleanup = stubTopSites(sandbox);
+  sandbox.stub(TopSites, "_fetchIcon");
+  TopSites._startedUp = true;
+
+  TopSites._storage.initialized = true;
+
+  await TopSites.refresh({ broadcast: false });
+
+  Assert.ok(
+    TopSites._storage.init.notCalled,
+    "TopSites._storage.init was not called."
+  );
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_refresh_handles_indexedDB_errors() {
+  let sandbox = sinon.createSandbox();
+
+  info(
+    "TopSites.refresh should dispatch AlsoToPreloaded when broadcast is false"
+  );
+
+  let cleanup = stubTopSites(sandbox);
+  sandbox.stub(TopSites, "_fetchIcon");
+  TopSites._startedUp = true;
+
+  TopSites._storage.get.throws(new Error());
+
+  try {
+    await TopSites.refresh({ broadcast: false });
+    Assert.ok(true, "refresh should have succeeded");
+  } catch (e) {
+    Assert.ok(false, "Should not have thrown");
+  }
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_updateSectionPrefs_on_UPDATE_SECTION_PREFS() {
+  let sandbox = sinon.createSandbox();
+
+  info(
+    "TopSites.onAction should call updateSectionPrefs on UPDATE_SECTION_PREFS"
+  );
+
+  let cleanup = stubTopSites(sandbox);
+  sandbox.stub(TopSites, "updateSectionPrefs");
+  TopSites.onAction({
+    type: at.UPDATE_SECTION_PREFS,
+    data: { id: "topsites" },
+  });
+
+  Assert.ok(
+    TopSites.updateSectionPrefs.calledOnce,
+    "TopSites.updateSectionPrefs called once"
+  );
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(
+  async function test_updateSectionPrefs_dispatch_TOP_SITES_PREFS_UPDATED() {
+    let sandbox = sinon.createSandbox();
+
+    info("TopSites.updateSectionPrefs should dispatch TOP_SITES_PREFS_UPDATED");
+
+    let cleanup = stubTopSites(sandbox);
+    await TopSites.updateSectionPrefs({ collapsed: true });
+    Assert.ok(
+      TopSites.store.dispatch.calledWithExactly(
+        ac.BroadcastToContent({
+          type: at.TOP_SITES_PREFS_UPDATED,
+          data: { pref: { collapsed: true } },
+        })
+      )
+    );
+
+    sandbox.restore();
+    await cleanup();
+  }
+);
+
+add_task(async function test_allocatePositions() {
+  let sandbox = sinon.createSandbox();
+
+  info("TopSites.allocationPositions should allocate positions and dispatch");
+
+  let cleanup = stubTopSites(sandbox);
+
+  let sov = {
+    name: "SOV-20230518215316",
+    allocations: [
+      {
+        position: 1,
+        allocation: [
+          {
+            partner: "amp",
+            percentage: 100,
+          },
+          {
+            partner: "moz-sales",
+            percentage: 0,
+          },
+        ],
+      },
+      {
+        position: 2,
+        allocation: [
+          {
+            partner: "amp",
+            percentage: 80,
+          },
+          {
+            partner: "moz-sales",
+            percentage: 20,
+          },
+        ],
+      },
+    ],
+  };
+
+  sandbox.stub(TopSites._contile, "sov").get(() => sov);
+
+  sandbox.stub(Sampling, "ratioSample");
+  Sampling.ratioSample.onCall(0).resolves(0);
+  Sampling.ratioSample.onCall(1).resolves(1);
+
+  await TopSites.allocatePositions();
+
+  Assert.ok(
+    TopSites.store.dispatch.calledOnce,
+    "TopSites.store.dispatch called once"
+  );
+  Assert.ok(
+    TopSites.store.dispatch.calledWithExactly(
+      ac.OnlyToMain({
+        type: at.SOV_UPDATED,
+        data: {
+          ready: true,
+          positions: [
+            { position: 1, assignedPartner: "amp" },
+            { position: 2, assignedPartner: "moz-sales" },
+          ],
+        },
+      })
+    )
+  );
+
+  Sampling.ratioSample.onCall(2).resolves(0);
+  Sampling.ratioSample.onCall(3).resolves(0);
+
+  await TopSites.allocatePositions();
+
+  Assert.ok(
+    TopSites.store.dispatch.calledTwice,
+    "TopSites.store.dispatch called twice"
+  );
+  Assert.ok(
+    TopSites.store.dispatch.calledWithExactly(
+      ac.OnlyToMain({
+        type: at.SOV_UPDATED,
+        data: {
+          ready: true,
+          positions: [
+            { position: 1, assignedPartner: "amp" },
+            { position: 2, assignedPartner: "amp" },
+          ],
+        },
+      })
+    )
+  );
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getScreenshotPreview() {
+  let sandbox = sinon.createSandbox();
+
+  info(
+    "TopSites.getScreenshotPreview should dispatch preview if request is succesful"
+  );
+
+  let cleanup = stubTopSites(sandbox);
+  await TopSites.getScreenshotPreview("custom", 1234);
+
+  Assert.ok(TopSites.store.dispatch.calledOnce);
+  Assert.ok(
+    TopSites.store.dispatch.calledWithExactly(
+      ac.OnlyToOneContent(
+        {
+          data: { preview: FAKE_SCREENSHOT, url: "custom" },
+          type: at.PREVIEW_RESPONSE,
+        },
+        1234
+      )
+    )
+  );
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_getScreenshotPreview() {
+  let sandbox = sinon.createSandbox();
+
+  info(
+    "TopSites.getScreenshotPreview should return empty string if request fails"
+  );
+
+  let cleanup = stubTopSites(sandbox);
+  Screenshots.getScreenshotForURL.resolves(Promise.resolve(null));
+  await TopSites.getScreenshotPreview("custom", 1234);
+
+  Assert.ok(TopSites.store.dispatch.calledOnce);
+  Assert.ok(
+    TopSites.store.dispatch.calledWithExactly(
+      ac.OnlyToOneContent(
+        {
+          data: { preview: "", url: "custom" },
+          type: at.PREVIEW_RESPONSE,
+        },
+        1234
+      )
+    )
+  );
+
+  Screenshots.getScreenshotForURL.resolves(FAKE_SCREENSHOT);
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_onAction_part_1() {
+  let sandbox = sinon.createSandbox();
+
+  info("TopSites.onAction should call getScreenshotPreview on PREVIEW_REQUEST");
+
+  let cleanup = stubTopSites(sandbox);
+  sandbox.stub(TopSites, "getScreenshotPreview");
+  TopSites.onAction({
+    type: at.PREVIEW_REQUEST,
+    data: { url: "foo" },
+    meta: { fromTarget: 1234 },
+  });
+
+  Assert.ok(
+    TopSites.getScreenshotPreview.calledOnce,
+    "TopSites.getScreenshotPreview called once"
+  );
+  Assert.ok(TopSites.getScreenshotPreview.calledWithExactly("foo", 1234));
+
+  info("TopSites.onAction should refresh on SYSTEM_TICK");
+  sandbox.stub(TopSites, "refresh");
+  TopSites.onAction({ type: at.SYSTEM_TICK });
+
+  Assert.ok(TopSites.refresh.calledOnce, "TopSites.refresh called once");
+  Assert.ok(TopSites.refresh.calledWithExactly({ broadcast: false }));
+
+  info(
+    "TopSites.onAction should call with correct parameters on TOP_SITES_PIN"
+  );
+  sandbox.stub(NewTabUtils.pinnedLinks, "pin");
+  sandbox.spy(TopSites, "pin");
+
+  let pinAction = {
+    type: at.TOP_SITES_PIN,
+    data: { site: { url: "foo.com" }, index: 7 },
+  };
+  TopSites.onAction(pinAction);
+  Assert.ok(
+    NewTabUtils.pinnedLinks.pin.calledOnce,
+    "NewTabUtils.pinnedLinks.pin called once"
+  );
+  Assert.ok(
+    NewTabUtils.pinnedLinks.pin.calledWithExactly(
+      pinAction.data.site,
+      pinAction.data.index
+    )
+  );
+  Assert.ok(
+    TopSites.pin.calledOnce,
+    "TopSites.onAction should call pin on TOP_SITES_PIN"
+  );
+
+  info(
+    "TopSites.onAction should unblock a previously blocked top site if " +
+      "we are now adding it manually via 'Add a Top Site' option"
+  );
+  sandbox.stub(NewTabUtils.blockedLinks, "unblock");
+  pinAction = {
+    type: at.TOP_SITES_PIN,
+    data: { site: { url: "foo.com" }, index: -1 },
+  };
+  TopSites.onAction(pinAction);
+  Assert.ok(
+    NewTabUtils.blockedLinks.unblock.calledWith({
+      url: pinAction.data.site.url,
+    })
+  );
+
+  info("TopSites.onAction should call insert on TOP_SITES_INSERT");
+  sandbox.stub(TopSites, "insert");
+  let addAction = {
+    type: at.TOP_SITES_INSERT,
+    data: { site: { url: "foo.com" } },
+  };
+
+  TopSites.onAction(addAction);
+  Assert.ok(TopSites.insert.calledOnce, "TopSites.insert called once");
+
+  info(
+    "TopSites.onAction should call unpin with correct parameters " +
+      "on TOP_SITES_UNPIN"
+  );
+
+  sandbox
+    .stub(NewTabUtils.pinnedLinks, "links")
+    .get(() => [
+      null,
+      null,
+      { url: "foo.com" },
+      null,
+      null,
+      null,
+      null,
+      null,
+      FAKE_LINKS[0],
+    ]);
+  sandbox.stub(NewTabUtils.pinnedLinks, "unpin");
+
+  let unpinAction = {
+    type: at.TOP_SITES_UNPIN,
+    data: { site: { url: "foo.com" } },
+  };
+  TopSites.onAction(unpinAction);
+  Assert.ok(
+    NewTabUtils.pinnedLinks.unpin.calledOnce,
+    "NewTabUtils.pinnedLinks.unpin called once"
+  );
+  Assert.ok(NewTabUtils.pinnedLinks.unpin.calledWith(unpinAction.data.site));
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_onAction_part_2() {
+  let sandbox = sinon.createSandbox();
+
+  info(
+    "TopSites.onAction should call refresh without a target if we clear " +
+      "history with PLACES_HISTORY_CLEARED"
+  );
+
+  let cleanup = stubTopSites(sandbox);
+  sandbox.stub(TopSites, "refresh");
+  TopSites.onAction({ type: at.PLACES_HISTORY_CLEARED });
+
+  Assert.ok(TopSites.refresh.calledOnce, "TopSites.refresh called once");
+  Assert.ok(TopSites.refresh.calledWithExactly({ broadcast: true }));
+
+  TopSites.refresh.resetHistory();
+
+  info(
+    "TopSites.onAction should call refresh without a target " +
+      "if we remove a Topsite from history"
+  );
+  TopSites.onAction({ type: at.PLACES_LINKS_DELETED });
+
+  Assert.ok(TopSites.refresh.calledOnce, "TopSites.refresh called once");
+  Assert.ok(TopSites.refresh.calledWithExactly({ broadcast: true }));
+
+  info("TopSites.onAction should call init on INIT action");
+  TopSites.onAction({ type: at.PLACES_LINKS_DELETED });
+  sandbox.stub(TopSites, "init");
+  TopSites.onAction({ type: at.INIT });
+  Assert.ok(TopSites.init.calledOnce, "TopSites.init called once");
+
+  info("TopSites.onAction should call refresh on PLACES_LINK_BLOCKED action");
+  TopSites.refresh.resetHistory();
+  await TopSites.onAction({ type: at.PLACES_LINK_BLOCKED });
+  Assert.ok(TopSites.refresh.calledOnce, "TopSites.refresh called once");
+  Assert.ok(TopSites.refresh.calledWithExactly({ broadcast: true }));
+
+  info("TopSites.onAction should call refresh on PLACES_LINKS_CHANGED action");
+  TopSites.refresh.resetHistory();
+  await TopSites.onAction({ type: at.PLACES_LINKS_CHANGED });
+  Assert.ok(TopSites.refresh.calledOnce, "TopSites.refresh called once");
+  Assert.ok(TopSites.refresh.calledWithExactly({ broadcast: false }));
+
+  info(
+    "TopSites.onAction should call pin with correct args on " +
+      "TOP_SITES_INSERT without an index specified"
+  );
+  sandbox.stub(NewTabUtils.pinnedLinks, "pin");
+
+  let addAction = {
+    type: at.TOP_SITES_INSERT,
+    data: { site: { url: "foo.bar", label: "foo" } },
+  };
+  TopSites.onAction(addAction);
+  Assert.ok(
+    NewTabUtils.pinnedLinks.pin.calledOnce,
+    "NewTabUtils.pinnedLinks.pin called once"
+  );
+  Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(addAction.data.site, 0));
+
+  info(
+    "TopSites.onAction should call pin with correct args on " +
+      "TOP_SITES_INSERT"
+  );
+  NewTabUtils.pinnedLinks.pin.resetHistory();
+  let dropAction = {
+    type: at.TOP_SITES_INSERT,
+    data: { site: { url: "foo.bar", label: "foo" }, index: 3 },
+  };
+  TopSites.onAction(dropAction);
+  Assert.ok(
+    NewTabUtils.pinnedLinks.pin.calledOnce,
+    "NewTabUtils.pinnedLinks.pin called once"
+  );
+  Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(dropAction.data.site, 3));
+
+  // TopSites.init needs to actually run in order to register the observers that'll
+  // be removed in the following UNINIT test, otherwise uninit will throw.
+  TopSites.init.restore();
+  TopSites.init();
+
+  info("TopSites.onAction should remove the expiration filter on UNINIT");
+  sandbox.stub(PageThumbs, "removeExpirationFilter");
+  TopSites.onAction({ type: "UNINIT" });
+  Assert.ok(
+    PageThumbs.removeExpirationFilter.calledOnce,
+    "PageThumbs.removeExpirationFilter called once"
+  );
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_onAction_part_3() {
+  let sandbox = sinon.createSandbox();
+
+  let cleanup = stubTopSites(sandbox);
+
+  info(
+    "TopSites.onAction should call updatePinnedSearchShortcuts " +
+      "on UPDATE_PINNED_SEARCH_SHORTCUTS action"
+  );
+  sandbox.stub(TopSites, "updatePinnedSearchShortcuts");
+  let addedShortcuts = [
+    {
+      url: "https://google.com",
+      searchVendor: "google",
+      label: "google",
+      searchTopSite: true,
+    },
+  ];
+  await TopSites.onAction({
+    type: at.UPDATE_PINNED_SEARCH_SHORTCUTS,
+    data: { addedShortcuts },
+  });
+  Assert.ok(
+    TopSites.updatePinnedSearchShortcuts.calledOnce,
+    "TopSites.updatePinnedSearchShortcuts called once"
+  );
+
+  info(
+    "TopSites.onAction should refresh from Contile on " +
+      "SHOW_SPONSORED_PREF if Contile is enabled"
+  );
+  sandbox.spy(TopSites._contile, "refresh");
+  let prefChangeAction = {
+    type: at.PREF_CHANGED,
+    data: { name: SHOW_SPONSORED_PREF },
+  };
+  sandbox.stub(NimbusFeatures.newtab, "getVariable").returns(true);
+  TopSites.onAction(prefChangeAction);
+
+  Assert.ok(
+    TopSites._contile.refresh.calledOnce,
+    "TopSites._contile.refresh called once"
+  );
+
+  info(
+    "TopSites.onAction should not refresh from Contile on " +
+      "SHOW_SPONSORED_PREF if Contile is disabled"
+  );
+  NimbusFeatures.newtab.getVariable.returns(false);
+  TopSites._contile.refresh.resetHistory();
+  TopSites.onAction(prefChangeAction);
+
+  Assert.ok(
+    !TopSites._contile.refresh.calledOnce,
+    "TopSites._contile.refresh never called"
+  );
+
+  info(
+    "TopSites.onAction should reset Contile cache prefs " +
+      "when SHOW_SPONSORED_PREF is false"
+  );
+  Services.prefs.setStringPref(CONTILE_CACHE_PREF, "[]");
+  Services.prefs.setIntPref(
+    CONTILE_CACHE_LAST_FETCH_PREF,
+    Math.round(Date.now() / 1000)
+  );
+  Services.prefs.setIntPref(CONTILE_CACHE_VALID_FOR_SECONDS_PREF, 15 * 60);
+  prefChangeAction = {
+    type: at.PREF_CHANGED,
+    data: { name: SHOW_SPONSORED_PREF, value: false },
+  };
+  NimbusFeatures.newtab.getVariable.returns(true);
+  TopSites._contile.refresh.resetHistory();
+
+  TopSites.onAction(prefChangeAction);
+  Assert.ok(!Services.prefs.prefHasUserValue(CONTILE_CACHE_PREF));
+  Assert.ok(!Services.prefs.prefHasUserValue(CONTILE_CACHE_LAST_FETCH_PREF));
+  Assert.ok(
+    !Services.prefs.prefHasUserValue(CONTILE_CACHE_VALID_FOR_SECONDS_PREF)
+  );
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_insert_part_1() {
+  let sandbox = sinon.createSandbox();
+  sandbox.stub(NewTabUtils.pinnedLinks, "pin");
+  let cleanup = stubTopSites(sandbox);
+
+  info("TopSites.insert should pin site in first slot of empty pinned list");
+  Screenshots.getScreenshotForURL.resolves(Promise.resolve(null));
+  await TopSites.getScreenshotPreview("custom", 1234);
+
+  Assert.ok(TopSites.store.dispatch.calledOnce);
+  Assert.ok(
+    TopSites.store.dispatch.calledWithExactly(
+      ac.OnlyToOneContent(
+        {
+          data: { preview: "", url: "custom" },
+          type: at.PREVIEW_RESPONSE,
+        },
+        1234
+      )
+    )
+  );
+
+  Screenshots.getScreenshotForURL.resolves(FAKE_SCREENSHOT);
+
+  {
+    info(
+      "TopSites.insert should pin site in first slot of pinned list with " +
+        "empty first slot"
+    );
+
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [null, { url: "example.com" }]);
+    let site = { url: "foo.bar", label: "foo" };
+    await TopSites.insert({ data: { site } });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledOnce,
+      "NewTabUtils.pinnedLinks.pin called once"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site, 0));
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+  }
+
+  {
+    info(
+      "TopSites.insert should move a pinned site in first slot to the " +
+        "next slot: part 1"
+    );
+    let site1 = { url: "example.com" };
+    sandbox.stub(NewTabUtils.pinnedLinks, "links").get(() => [site1]);
+    let site = { url: "foo.bar", label: "foo" };
+
+    await TopSites.insert({ data: { site } });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledTwice,
+      "NewTabUtils.pinnedLinks.pin called twice"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site, 0));
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site1, 1));
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+  }
+
+  {
+    info(
+      "TopSites.insert should move a pinned site in first slot to the " +
+        "next slot: part 2"
+    );
+    let site1 = { url: "example.com" };
+    let site2 = { url: "example.org" };
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [site1, null, site2]);
+    let site = { url: "foo.bar", label: "foo" };
+    await TopSites.insert({ data: { site } });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledTwice,
+      "NewTabUtils.pinnedLinks.pin called twice"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site, 0));
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site1, 1));
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+  }
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_insert_part_2() {
+  let sandbox = sinon.createSandbox();
+  sandbox.stub(NewTabUtils.pinnedLinks, "pin");
+  let cleanup = stubTopSites(sandbox);
+
+  {
+    info(
+      "TopSites.insert should unpin the last site if all slots are " +
+        "already pinned"
+    );
+    let site1 = { url: "example.com" };
+    let site2 = { url: "example.org" };
+    let site3 = { url: "example.net" };
+    let site4 = { url: "example.biz" };
+    let site5 = { url: "example.info" };
+    let site6 = { url: "example.news" };
+    let site7 = { url: "example.lol" };
+    let site8 = { url: "example.golf" };
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [site1, site2, site3, site4, site5, site6, site7, site8]);
+    TopSites.store.state.Prefs.values.topSitesRows = 1;
+    let site = { url: "foo.bar", label: "foo" };
+    await TopSites.insert({ data: { site } });
+    Assert.equal(
+      NewTabUtils.pinnedLinks.pin.callCount,
+      8,
+      "NewTabUtils.pinnedLinks.pin called 8 times"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site, 0));
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site1, 1));
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site2, 2));
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site3, 3));
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site4, 4));
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site5, 5));
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site6, 6));
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site7, 7));
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+  }
+
+  {
+    info("TopSites.insert should trigger refresh on TOP_SITES_INSERT");
+    sandbox.stub(TopSites, "refresh");
+    let addAction = {
+      type: at.TOP_SITES_INSERT,
+      data: { site: { url: "foo.com" } },
+    };
+
+    await TopSites.insert(addAction);
+
+    Assert.ok(TopSites.refresh.calledOnce, "TopSites.refresh called once");
+  }
+
+  {
+    info("TopSites.insert should correctly handle different index values");
+    let index = -1;
+    let site = { url: "foo.bar", label: "foo" };
+    let action = { data: { index, site } };
+
+    await TopSites.insert(action);
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site, 0));
+
+    index = undefined;
+    await TopSites.insert(action);
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site, 0));
+
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+  }
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_insert_part_3() {
+  let sandbox = sinon.createSandbox();
+  sandbox.stub(NewTabUtils.pinnedLinks, "pin");
+  let cleanup = stubTopSites(sandbox);
+
+  {
+    info("TopSites.insert should pin site in specified slot that is free");
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [null, { url: "example.com" }]);
+
+    let site = { url: "foo.bar", label: "foo" };
+
+    await TopSites.insert({ data: { index: 2, site, draggedFromIndex: 0 } });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledOnce,
+      "NewTabUtils.pinnedLinks.pin called once"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site, 2));
+
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+  }
+
+  {
+    info(
+      "TopSites.insert should move a pinned site in specified slot " +
+        "to the next slot"
+    );
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [null, null, { url: "example.com" }]);
+
+    let site = { url: "foo.bar", label: "foo" };
+
+    await TopSites.insert({ data: { index: 2, site, draggedFromIndex: 3 } });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledTwice,
+      "NewTabUtils.pinnedLinks.pin called twice"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site, 2));
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledWith({ url: "example.com" }, 3)
+    );
+
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+  }
+
+  {
+    info(
+      "TopSites.insert should move pinned sites in the direction " +
+        "of the dragged site"
+    );
+
+    let site1 = { url: "foo.bar", label: "foo" };
+    let site2 = { url: "example.com", label: "example" };
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [null, null, site2]);
+
+    await TopSites.insert({
+      data: { index: 2, site: site1, draggedFromIndex: 0 },
+    });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledTwice,
+      "NewTabUtils.pinnedLinks.pin called twice"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site1, 2));
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site2, 1));
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+
+    await TopSites.insert({
+      data: { index: 2, site: site1, draggedFromIndex: 5 },
+    });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledTwice,
+      "NewTabUtils.pinnedLinks.pin called twice"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site1, 2));
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site2, 3));
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+  }
+
+  {
+    info("TopSites.insert should not insert past the visible top sites");
+    let site1 = { url: "foo.bar", label: "foo" };
+    await TopSites.insert({
+      data: { index: 42, site: site1, draggedFromIndex: 0 },
+    });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.notCalled,
+      "NewTabUtils.pinnedLinks.pin wasn't called"
+    );
+
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+  }
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_pin_part_1() {
+  let sandbox = sinon.createSandbox();
+  sandbox.stub(NewTabUtils.pinnedLinks, "pin");
+  sandbox.spy(TopSites.pinnedCache, "request");
+  let cleanup = stubTopSites(sandbox);
+
+  {
+    info("TopSites.pin should pin site in specified slot empty pinned list");
+    let site = {
+      url: "foo.bar",
+      label: "foo",
+      customScreenshotURL: "screenshot",
+    };
+    Assert.ok(
+      TopSites.pinnedCache.request.notCalled,
+      "TopSites.pinnedCache.request not called"
+    );
+    await TopSites.pin({ data: { index: 2, site } });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.called,
+      "NewTabUtils.pinnedLinks.pin called"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site, 2));
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    TopSites.pinnedCache.request.resetHistory();
+  }
+
+  {
+    info(
+      "TopSites.pin should lookup the link object to update the custom " +
+        "screenshot"
+    );
+    let site = {
+      url: "foo.bar",
+      label: "foo",
+      customScreenshotURL: "screenshot",
+    };
+    Assert.ok(
+      TopSites.pinnedCache.request.notCalled,
+      "TopSites.pinnedCache.request not called"
+    );
+    await TopSites.pin({ data: { index: 2, site } });
+    Assert.ok(
+      TopSites.pinnedCache.request.called,
+      "TopSites.pinnedCache.request called"
+    );
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    TopSites.pinnedCache.request.resetHistory();
+  }
+
+  {
+    info(
+      "TopSites.pin should lookup the link object to update the custom " +
+        "screenshot when the custom screenshot is initially null"
+    );
+    let site = {
+      url: "foo.bar",
+      label: "foo",
+      customScreenshotURL: null,
+    };
+    Assert.ok(
+      TopSites.pinnedCache.request.notCalled,
+      "TopSites.pinnedCache.request not called"
+    );
+    await TopSites.pin({ data: { index: 2, site } });
+    Assert.ok(
+      TopSites.pinnedCache.request.called,
+      "TopSites.pinnedCache.request called"
+    );
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    TopSites.pinnedCache.request.resetHistory();
+  }
+
+  {
+    info(
+      "TopSites.pin should not do a link object lookup if custom " +
+        "screenshot field is not set"
+    );
+    let site = { url: "foo.bar", label: "foo" };
+    await TopSites.pin({ data: { index: 2, site } });
+    Assert.ok(
+      !TopSites.pinnedCache.request.called,
+      "TopSites.pinnedCache.request never called"
+    );
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    TopSites.pinnedCache.request.resetHistory();
+  }
+
+  {
+    info(
+      "TopSites.pin should pin site in specified slot of pinned " +
+        "list that is free"
+    );
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [null, { url: "example.com" }]);
+
+    let site = { url: "foo.bar", label: "foo" };
+    await TopSites.pin({ data: { index: 2, site } });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledOnce,
+      "NewTabUtils.pinnedLinks.pin called once"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site, 2));
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+  }
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_pin_part_2() {
+  let sandbox = sinon.createSandbox();
+  sandbox.stub(NewTabUtils.pinnedLinks, "pin");
+
+  {
+    info("TopSites.pin should save the searchTopSite attribute if set");
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [null, { url: "example.com" }]);
+
+    let site = { url: "foo.bar", label: "foo", searchTopSite: true };
+    let cleanup = stubTopSites(sandbox);
+    await TopSites.pin({ data: { index: 2, site } });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledOnce,
+      "NewTabUtils.pinnedLinks.pin called once"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.firstCall.args[0].searchTopSite);
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    await cleanup();
+  }
+
+  {
+    info(
+      "TopSites.pin should NOT move a pinned site in specified " +
+        "slot to the next slot"
+    );
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [null, null, { url: "example.com" }]);
+
+    let site = { url: "foo.bar", label: "foo" };
+    let cleanup = stubTopSites(sandbox);
+    await TopSites.pin({ data: { index: 2, site } });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledOnce,
+      "NewTabUtils.pinnedLinks.pin called once"
+    );
+    Assert.ok(NewTabUtils.pinnedLinks.pin.calledWith(site, 2));
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    await cleanup();
+  }
+
+  {
+    info(
+      "TopSites.pin should properly update LinksCache object " +
+        "properties between migrations"
+    );
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [{ url: "https://foo.com/" }]);
+
+    let cleanup = stubTopSites(sandbox);
+    let pinnedLinks = await TopSites.pinnedCache.request();
+    Assert.equal(pinnedLinks.length, 1);
+    TopSites.pinnedCache.expire();
+
+    pinnedLinks[0].__sharedCache.updateLink("screenshot", "foo");
+
+    pinnedLinks = await TopSites.pinnedCache.request();
+    Assert.equal(pinnedLinks[0].screenshot, "foo");
+
+    // Force cache expiration in order to trigger a migration of objects
+    TopSites.pinnedCache.expire();
+    pinnedLinks[0].__sharedCache.updateLink("screenshot", "bar");
+
+    pinnedLinks = await TopSites.pinnedCache.request();
+    Assert.equal(pinnedLinks[0].screenshot, "bar");
+    await cleanup();
+  }
+
+  sandbox.restore();
+});
+
+add_task(async function test_pin_part_3() {
+  let sandbox = sinon.createSandbox();
+  sandbox.stub(NewTabUtils.pinnedLinks, "pin");
+  sandbox.spy(TopSites, "insert");
+
+  {
+    info("TopSites.pin should call insert if index < 0");
+    let site = { url: "foo.bar", label: "foo" };
+    let action = { data: { index: -1, site } };
+    let cleanup = stubTopSites(sandbox);
+    await TopSites.pin(action);
+
+    Assert.ok(TopSites.insert.calledOnce, "TopSites.insert called once");
+    Assert.ok(TopSites.insert.calledWithExactly(action));
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    TopSites.insert.resetHistory();
+    await cleanup();
+  }
+
+  {
+    info("TopSites.pin should not call insert if index == 0");
+    let site = { url: "foo.bar", label: "foo" };
+    let action = { data: { index: 0, site } };
+    let cleanup = stubTopSites(sandbox);
+    await TopSites.pin(action);
+
+    Assert.ok(!TopSites.insert.called, "TopSites.insert not called");
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    await cleanup();
+  }
+
+  {
+    info("TopSites.pin should trigger refresh on TOP_SITES_PIN");
+    let cleanup = stubTopSites(sandbox);
+    sandbox.stub(TopSites, "refresh");
+    let pinExistingAction = {
+      type: at.TOP_SITES_PIN,
+      data: { site: FAKE_LINKS[4], index: 4 },
+    };
+
+    await TopSites.pin(pinExistingAction);
+
+    Assert.ok(TopSites.refresh.calledOnce, "TopSites.refresh called once");
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    await cleanup();
+  }
+
+  sandbox.restore();
+});
+
+add_task(async function test_integration() {
+  let sandbox = sinon.createSandbox();
+
+  info("Test adding a pinned site and removing it with actions");
+  let cleanup = stubTopSites(sandbox);
+
+  let resolvers = [];
+  TopSites.store.dispatch = sandbox.stub().callsFake(() => {
+    resolvers.shift()();
+  });
+  TopSites._startedUp = true;
+  sandbox.stub(TopSites, "_fetchScreenshot");
+
+  let forDispatch = action =>
+    new Promise(resolve => {
+      resolvers.push(resolve);
+      TopSites.onAction(action);
+    });
+
+  TopSites._requestRichIcon = sandbox.stub();
+  let url = "https://pin.me";
+  sandbox.stub(NewTabUtils.pinnedLinks, "pin").callsFake(link => {
+    NewTabUtils.pinnedLinks.links.push(link);
+  });
+
+  await forDispatch({ type: at.TOP_SITES_INSERT, data: { site: { url } } });
+  NewTabUtils.pinnedLinks.links.pop();
+  await forDispatch({ type: at.PLACES_LINK_BLOCKED });
+
+  Assert.ok(
+    TopSites.store.dispatch.calledTwice,
+    "TopSites.store.dispatch called twice"
+  );
+  Assert.equal(
+    TopSites.store.dispatch.firstCall.args[0].data.links[0].url,
+    url
+  );
+  Assert.equal(
+    TopSites.store.dispatch.secondCall.args[0].data.links[0].url,
+    FAKE_LINKS[0].url
+  );
+
+  sandbox.restore();
+  await cleanup();
+});
+
+add_task(async function test_improvesearch_noDefaultSearchTile_experiment() {
+  let sandbox = sinon.createSandbox();
+  const NO_DEFAULT_SEARCH_TILE_PREF = "improvesearch.noDefaultSearchTile";
+
+  sandbox.stub(SearchService.prototype, "getDefault").resolves({
+    identifier: "google",
+    searchForm: "google.com",
+  });
+
+  {
+    info(
+      "TopSites.getLinksWithDefaults should filter out alexa top 5 " +
+        "search from the default sites"
+    );
+    let cleanup = stubTopSites(sandbox);
+    TopSites.store.state.Prefs.values[NO_DEFAULT_SEARCH_TILE_PREF] = true;
+    let top5Test = [
+      "https://google.com",
+      "https://search.yahoo.com",
+      "https://yahoo.com",
+      "https://bing.com",
+      "https://ask.com",
+      "https://duckduckgo.com",
+    ];
+
+    gGetTopSitesStub.resolves([
+      { url: "https://amazon.com" },
+      ...top5Test.map(url => ({ url })),
+    ]);
+
+    const urlsReturned = (await TopSites.getLinksWithDefaults()).map(
+      link => link.url
+    );
+    Assert.ok(
+      urlsReturned.includes("https://amazon.com"),
+      "amazon included in default links"
+    );
+    top5Test.forEach(url =>
+      Assert.ok(!urlsReturned.includes(url), `Should not include ${url}`)
+    );
+
+    gGetTopSitesStub.resolves(FAKE_LINKS);
+    await cleanup();
+  }
+
+  {
+    info(
+      "TopSites.getLinksWithDefaults should not filter out alexa, default " +
+        "search from the query results if the experiment pref is off"
+    );
+    let cleanup = stubTopSites(sandbox);
+    TopSites.store.state.Prefs.values[NO_DEFAULT_SEARCH_TILE_PREF] = false;
+
+    gGetTopSitesStub.resolves([
+      { url: "https://google.com" },
+      { url: "https://foo.com" },
+      { url: "https://duckduckgo" },
+    ]);
+    let urlsReturned = (await TopSites.getLinksWithDefaults()).map(
+      link => link.url
+    );
+
+    Assert.ok(urlsReturned.includes("https://google.com"));
+    gGetTopSitesStub.resolves(FAKE_LINKS);
+    await cleanup();
+  }
+
+  {
+    info(
+      "TopSites.getLinksWithDefaults should filter out the current " +
+        "default search from the default sites"
+    );
+    let cleanup = stubTopSites(sandbox);
+    TopSites.store.state.Prefs.values[NO_DEFAULT_SEARCH_TILE_PREF] = true;
+
+    sandbox.stub(TopSites, "_currentSearchHostname").get(() => "amazon");
+    TopSites.onAction({
+      type: at.PREFS_INITIAL_VALUES,
+      data: { "default.sites": "google.com,amazon.com" },
+    });
+    gGetTopSitesStub.resolves([{ url: "https://foo.com" }]);
+
+    let urlsReturned = (await TopSites.getLinksWithDefaults()).map(
+      link => link.url
+    );
+    Assert.ok(!urlsReturned.includes("https://amazon.com"));
+
+    gGetTopSitesStub.resolves(FAKE_LINKS);
+    await cleanup();
+  }
+
+  {
+    info(
+      "TopSites.getLinksWithDefaults should not filter out current " +
+        "default search from pinned sites even if it matches the current " +
+        "default search"
+    );
+    let cleanup = stubTopSites(sandbox);
+    TopSites.store.state.Prefs.values[NO_DEFAULT_SEARCH_TILE_PREF] = true;
+
+    sandbox
+      .stub(NewTabUtils.pinnedLinks, "links")
+      .get(() => [{ url: "google.com" }]);
+    gGetTopSitesStub.resolves([{ url: "https://foo.com" }]);
+
+    let urlsReturned = (await TopSites.getLinksWithDefaults()).map(
+      link => link.url
+    );
+    Assert.ok(urlsReturned.includes("google.com"));
+
+    gGetTopSitesStub.resolves(FAKE_LINKS);
+    await cleanup();
+  }
+
+  sandbox.restore();
+});
+
+add_task(
+  async function test_improvesearch_noDefaultSearchTile_experiment_part_2() {
+    let sandbox = sinon.createSandbox();
+    const NO_DEFAULT_SEARCH_TILE_PREF = "improvesearch.noDefaultSearchTile";
+
+    sandbox.stub(SearchService.prototype, "getDefault").resolves({
+      identifier: "google",
+      searchForm: "google.com",
+    });
+
+    sandbox.stub(TopSites, "refresh");
+
+    {
+      info(
+        "TopSites.getLinksWithDefaults should call refresh and set " +
+          "._currentSearchHostname to the new engine hostname when the " +
+          "default search engine has been set"
+      );
+      let cleanup = stubTopSites(sandbox);
+      TopSites.store.state.Prefs.values[NO_DEFAULT_SEARCH_TILE_PREF] = true;
+
+      TopSites.observe(
+        null,
+        "browser-search-engine-modified",
+        "engine-default"
+      );
+      Assert.equal(TopSites._currentSearchHostname, "duckduckgo");
+      Assert.ok(TopSites.refresh.calledOnce, "TopSites.refresh called once");
+
+      gGetTopSitesStub.resolves(FAKE_LINKS);
+      TopSites.refresh.resetHistory();
+      await cleanup();
+    }
+
+    {
+      info(
+        "TopSites.getLinksWithDefaults should call refresh when the " +
+          "experiment pref has changed"
+      );
+      let cleanup = stubTopSites(sandbox);
+      TopSites.store.state.Prefs.values[NO_DEFAULT_SEARCH_TILE_PREF] = true;
+
+      TopSites.onAction({
+        type: at.PREF_CHANGED,
+        data: { name: NO_DEFAULT_SEARCH_TILE_PREF, value: true },
+      });
+      Assert.ok(
+        TopSites.refresh.calledOnce,
+        "TopSites.refresh was called once"
+      );
+
+      TopSites.onAction({
+        type: at.PREF_CHANGED,
+        data: { name: NO_DEFAULT_SEARCH_TILE_PREF, value: false },
+      });
+      Assert.ok(
+        TopSites.refresh.calledTwice,
+        "TopSites.refresh was called twice"
+      );
+
+      gGetTopSitesStub.resolves(FAKE_LINKS);
+      TopSites.refresh.resetHistory();
+      await cleanup();
+    }
+
+    sandbox.restore();
+  }
+);
+
+// eslint-disable-next-line max-statements
+add_task(async function test_improvesearch_topSitesSearchShortcuts() {
+  let sandbox = sinon.createSandbox();
+  let searchEngines = [{ aliases: ["@google"] }, { aliases: ["@amazon"] }];
+  sandbox
+    .stub(SearchService.prototype, "getAppProvidedEngines")
+    .resolves(searchEngines);
+  sandbox.stub(NewTabUtils.pinnedLinks, "pin").callsFake((site, index) => {
+    NewTabUtils.pinnedLinks.links[index] = site;
+  });
+
+  let prepTopSites = () => {
+    TopSites.store.state.Prefs.values[SEARCH_SHORTCUTS_EXPERIMENT_PREF] = true;
+    TopSites.store.state.Prefs.values[SEARCH_SHORTCUTS_SEARCH_ENGINES_PREF] =
+      "google,amazon";
+    TopSites.store.state.Prefs.values[SEARCH_SHORTCUTS_HAVE_PINNED_PREF] = "";
+  };
+
+  {
+    info(
+      "TopSites should updateCustomSearchShortcuts when experiment " +
+        "pref is turned on"
+    );
+    let cleanup = stubTopSites(sandbox);
+    prepTopSites();
+    TopSites.store.state.Prefs.values[SEARCH_SHORTCUTS_EXPERIMENT_PREF] = false;
+    sandbox.spy(TopSites, "updateCustomSearchShortcuts");
+
+    // turn the experiment on
+    TopSites.onAction({
+      type: at.PREF_CHANGED,
+      data: { name: SEARCH_SHORTCUTS_EXPERIMENT_PREF, value: true },
+    });
+
+    Assert.ok(
+      TopSites.updateCustomSearchShortcuts.calledOnce,
+      "TopSites.updateCustomSearchShortcuts called once"
+    );
+    TopSites.updateCustomSearchShortcuts.restore();
+    await cleanup();
+  }
+
+  {
+    info(
+      "TopSites should filter out default top sites that match a " +
+        "hostname of a search shortcut if previously blocked"
+    );
+    let cleanup = stubTopSites(sandbox);
+    prepTopSites();
+    TopSites.refreshDefaults("https://amazon.ca");
+    sandbox
+      .stub(NewTabUtils.blockedLinks, "links")
+      .value([{ url: "https://amazon.com" }]);
+    sandbox.stub(NewTabUtils.blockedLinks, "isBlocked").callsFake(site => {
+      return NewTabUtils.blockedLinks.links[0].url === site.url;
+    });
+
+    let urlsReturned = (await TopSites.getLinksWithDefaults()).map(
+      link => link.url
+    );
+    Assert.ok(!urlsReturned.includes("https://amazon.ca"));
+    await cleanup();
+  }
+
+  {
+    info("TopSites should update frecent search topsite icon");
+    let cleanup = stubTopSites(sandbox);
+    prepTopSites();
+    sandbox.stub(TopSites._tippyTopProvider, "processSite").callsFake(site => {
+      site.tippyTopIcon = "icon.png";
+      site.backgroundColor = "#fff";
+      return site;
+    });
+    gGetTopSitesStub.resolves([{ url: "https://google.com" }]);
+
+    let urlsReturned = await TopSites.getLinksWithDefaults();
+
+    let defaultSearchTopsite = urlsReturned.find(
+      s => s.url === "https://google.com"
+    );
+    Assert.ok(defaultSearchTopsite.searchTopSite);
+    Assert.equal(defaultSearchTopsite.tippyTopIcon, "icon.png");
+    Assert.equal(defaultSearchTopsite.backgroundColor, "#fff");
+    gGetTopSitesStub.resolves(FAKE_LINKS);
+    TopSites._tippyTopProvider.processSite.restore();
+    await cleanup();
+  }
+
+  {
+    info("TopSites should update default search topsite icon");
+    let cleanup = stubTopSites(sandbox);
+    prepTopSites();
+    sandbox.stub(TopSites._tippyTopProvider, "processSite").callsFake(site => {
+      site.tippyTopIcon = "icon.png";
+      site.backgroundColor = "#fff";
+      return site;
+    });
+    gGetTopSitesStub.resolves([{ url: "https://foo.com" }]);
+    TopSites.onAction({
+      type: at.PREFS_INITIAL_VALUES,
+      data: { "default.sites": "google.com,amazon.com" },
+    });
+
+    let urlsReturned = await TopSites.getLinksWithDefaults();
+
+    let defaultSearchTopsite = urlsReturned.find(
+      s => s.url === "https://amazon.com"
+    );
+    Assert.ok(defaultSearchTopsite.searchTopSite);
+    Assert.equal(defaultSearchTopsite.tippyTopIcon, "icon.png");
+    Assert.equal(defaultSearchTopsite.backgroundColor, "#fff");
+    gGetTopSitesStub.resolves(FAKE_LINKS);
+    TopSites._tippyTopProvider.processSite.restore();
+    TopSites.store.dispatch.resetHistory();
+    await cleanup();
+  }
+
+  {
+    info(
+      "TopSites should dispatch UPDATE_SEARCH_SHORTCUTS on " +
+        "updateCustomSearchShortcuts"
+    );
+    let cleanup = stubTopSites(sandbox);
+    prepTopSites();
+    TopSites.store.state.Prefs.values[
+      "improvesearch.noDefaultSearchTile"
+    ] = true;
+    await TopSites.updateCustomSearchShortcuts();
+    Assert.ok(
+      TopSites.store.dispatch.calledOnce,
+      "TopSites.store.dispatch called once"
+    );
+    Assert.ok(
+      TopSites.store.dispatch.calledWith({
+        data: {
+          searchShortcuts: [
+            {
+              keyword: "@google",
+              shortURL: "google",
+              url: "https://google.com",
+              backgroundColor: undefined,
+              smallFavicon:
+                "chrome://activity-stream/content/data/content/tippytop/favicons/google-com.ico",
+              tippyTopIcon:
+                "chrome://activity-stream/content/data/content/tippytop/images/google-com@2x.png",
+            },
+            {
+              keyword: "@amazon",
+              shortURL: "amazon",
+              url: "https://amazon.com",
+              backgroundColor: undefined,
+              smallFavicon:
+                "chrome://activity-stream/content/data/content/tippytop/favicons/amazon.ico",
+              tippyTopIcon:
+                "chrome://activity-stream/content/data/content/tippytop/images/amazon@2x.png",
+            },
+          ],
+        },
+        meta: {
+          from: "ActivityStream:Main",
+          to: "ActivityStream:Content",
+          isStartup: false,
+        },
+        type: "UPDATE_SEARCH_SHORTCUTS",
+      })
+    );
+    await cleanup();
+  }
+
+  sandbox.restore();
+});
+
+add_task(async function test_updatePinnedSearchShortcuts() {
+  let sandbox = sinon.createSandbox();
+  sandbox.stub(NewTabUtils.pinnedLinks, "pin");
+  sandbox.stub(NewTabUtils.pinnedLinks, "unpin");
+
+  {
+    info(
+      "TopSites.updatePinnedSearchShortcuts should unpin a " +
+        "shortcut in deletedShortcuts"
+    );
+    let cleanup = stubTopSites(sandbox);
+
+    let deletedShortcuts = [
+      {
+        url: "https://google.com",
+        searchVendor: "google",
+        label: "google",
+        searchTopSite: true,
+      },
+    ];
+    let addedShortcuts = [];
+    sandbox.stub(NewTabUtils.pinnedLinks, "links").get(() => [
+      null,
+      null,
+      {
+        url: "https://amazon.com",
+        searchVendor: "amazon",
+        label: "amazon",
+        searchTopSite: true,
+      },
+    ]);
+    TopSites.updatePinnedSearchShortcuts({ addedShortcuts, deletedShortcuts });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.notCalled,
+      "NewTabUtils.pinnedLinks.pin not called"
+    );
+    Assert.ok(
+      NewTabUtils.pinnedLinks.unpin.calledOnce,
+      "NewTabUtils.pinnedLinks.unpin called once"
+    );
+    Assert.ok(
+      NewTabUtils.pinnedLinks.unpin.calledWith({
+        url: "https://google.com",
+      })
+    );
+
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    NewTabUtils.pinnedLinks.unpin.resetHistory();
+    await cleanup();
+  }
+
+  {
+    info(
+      "TopSites.updatePinnedSearchShortcuts should pin a shortcut " +
+        "in addedShortcuts"
+    );
+    let cleanup = stubTopSites(sandbox);
+
+    let addedShortcuts = [
+      {
+        url: "https://google.com",
+        searchVendor: "google",
+        label: "google",
+        searchTopSite: true,
+      },
+    ];
+    let deletedShortcuts = [];
+    sandbox.stub(NewTabUtils.pinnedLinks, "links").get(() => [
+      null,
+      null,
+      {
+        url: "https://amazon.com",
+        searchVendor: "amazon",
+        label: "amazon",
+        searchTopSite: true,
+      },
+    ]);
+    TopSites.updatePinnedSearchShortcuts({ addedShortcuts, deletedShortcuts });
+    Assert.ok(
+      NewTabUtils.pinnedLinks.unpin.notCalled,
+      "NewTabUtils.pinnedLinks.unpin not called"
+    );
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledOnce,
+      "NewTabUtils.pinnedLinks.pin called once"
+    );
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledWith(
+        {
+          label: "google",
+          searchTopSite: true,
+          searchVendor: "google",
+          url: "https://google.com",
+        },
+        0
+      )
+    );
+
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    NewTabUtils.pinnedLinks.unpin.resetHistory();
+    await cleanup();
+  }
+
+  {
+    info(
+      "TopSites.updatePinnedSearchShortcuts should pin and unpin " +
+        "in the same action"
+    );
+    let cleanup = stubTopSites(sandbox);
+
+    let addedShortcuts = [
+      {
+        url: "https://google.com",
+        searchVendor: "google",
+        label: "google",
+        searchTopSite: true,
+      },
+      {
+        url: "https://ebay.com",
+        searchVendor: "ebay",
+        label: "ebay",
+        searchTopSite: true,
+      },
+    ];
+    let deletedShortcuts = [
+      {
+        url: "https://amazon.com",
+        searchVendor: "amazon",
+        label: "amazon",
+        searchTopSite: true,
+      },
+    ];
+
+    sandbox.stub(NewTabUtils.pinnedLinks, "links").get(() => [
+      { url: "https://foo.com" },
+      {
+        url: "https://amazon.com",
+        searchVendor: "amazon",
+        label: "amazon",
+        searchTopSite: true,
+      },
+    ]);
+    TopSites.updatePinnedSearchShortcuts({ addedShortcuts, deletedShortcuts });
+
+    Assert.ok(
+      NewTabUtils.pinnedLinks.unpin.calledOnce,
+      "NewTabUtils.pinnedLinks.unpin called once"
+    );
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledTwice,
+      "NewTabUtils.pinnedLinks.pin called twice"
+    );
+
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    NewTabUtils.pinnedLinks.unpin.resetHistory();
+    await cleanup();
+  }
+
+  {
+    info(
+      "TopSites.updatePinnedSearchShortcuts should pin a shortcut in " +
+        "addedShortcuts even if pinnedLinks is full"
+    );
+    let cleanup = stubTopSites(sandbox);
+
+    let addedShortcuts = [
+      {
+        url: "https://google.com",
+        searchVendor: "google",
+        label: "google",
+        searchTopSite: true,
+      },
+    ];
+    let deletedShortcuts = [];
+    sandbox.stub(NewTabUtils.pinnedLinks, "links").get(() => FAKE_LINKS);
+    TopSites.updatePinnedSearchShortcuts({ addedShortcuts, deletedShortcuts });
+
+    Assert.ok(
+      NewTabUtils.pinnedLinks.unpin.notCalled,
+      "NewTabUtils.pinnedLinks.unpin not called"
+    );
+    Assert.ok(
+      NewTabUtils.pinnedLinks.pin.calledWith(
+        { label: "google", searchTopSite: true, url: "https://google.com" },
+        0
+      ),
+      "NewTabUtils.pinnedLinks.unpin not called"
+    );
+
+    NewTabUtils.pinnedLinks.pin.resetHistory();
+    NewTabUtils.pinnedLinks.unpin.resetHistory();
+    await cleanup();
+  }
+
+  sandbox.restore();
+});
+
+// eslint-disable-next-line max-statements
+add_task(async function test_ContileIntegration() {
+  let sandbox = sinon.createSandbox();
+  Services.prefs.setStringPref(
+    TOP_SITES_BLOCKED_SPONSORS_PREF,
+    `["foo","bar"]`
+  );
+  sandbox.stub(NimbusFeatures.newtab, "getVariable").returns(true);
+
+  let fetchStub;
+
+  let prepTopSites = () => {
+    TopSites.store.state.Prefs.values[SHOW_SPONSORED_PREF] = true;
+    fetchStub = sandbox.stub(TopSites, "fetch");
+    function cleanupPrep() {
+      TopSites._contile._sites = [];
+      fetchStub.restore();
+    }
+    return cleanupPrep;
+  };
+
+  {
+    info("TopSites._fetchSites should fetch sites from Contile");
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+    fetchStub.resolves({
+      ok: true,
+      status: 200,
+      headers: new Map([
+        ["cache-control", "private, max-age=859, stale-if-error=10463"],
+      ]),
+      json: () =>
+        Promise.resolve({
+          tiles: [
+            {
+              url: "https://www.test.com",
+              image_url: "images/test-com.png",
+              click_url: "https://www.test-click.com",
+              impression_url: "https://www.test-impression.com",
+              name: "test",
+            },
+            {
+              url: "https://www.test1.com",
+              image_url: "images/test1-com.png",
+              click_url: "https://www.test1-click.com",
+              impression_url: "https://www.test1-impression.com",
+              name: "test1",
+            },
+          ],
+        }),
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(fetched);
+    Assert.equal(TopSites._contile.sites.length, 2);
+    await cleanup();
+    cleanupPrep();
+  }
+
+  {
+    info("TopSites._fetchSites should call allocatePositions");
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+    sandbox.stub(TopSites, "allocatePositions").resolves();
+    await TopSites._contile.refresh();
+
+    Assert.ok(
+      TopSites.allocatePositions.calledOnce,
+      "TopSites.allocatePositions called once"
+    );
+    await cleanup();
+    cleanupPrep();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should fetch SOV (Share-of-Voice) " +
+        "settings from Contile"
+    );
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+
+    let sov = {
+      name: "SOV-20230518215316",
+      allocations: [
+        {
+          position: 1,
+          allocation: [
+            {
+              partner: "foo",
+              percentage: 100,
+            },
+            {
+              partner: "bar",
+              percentage: 0,
+            },
+          ],
+        },
+        {
+          position: 2,
+          allocation: [
+            {
+              partner: "foo",
+              percentage: 80,
+            },
+            {
+              partner: "bar",
+              percentage: 20,
+            },
+          ],
+        },
+      ],
+    };
+    fetchStub.resolves({
+      ok: true,
+      status: 200,
+      headers: new Map([
+        ["cache-control", "private, max-age=859, stale-if-error=10463"],
+      ]),
+      json: () =>
+        Promise.resolve({
+          sov: btoa(JSON.stringify(sov)),
+          tiles: [
+            {
+              url: "https://www.test.com",
+              image_url: "images/test-com.png",
+              click_url: "https://www.test-click.com",
+              impression_url: "https://www.test-impression.com",
+              name: "test",
+            },
+            {
+              url: "https://www.test1.com",
+              image_url: "images/test1-com.png",
+              click_url: "https://www.test1-click.com",
+              impression_url: "https://www.test1-impression.com",
+              name: "test1",
+            },
+          ],
+        }),
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(fetched);
+    Assert.deepEqual(TopSites._contile.sov, sov);
+    Assert.equal(TopSites._contile.sites.length, 2);
+    await cleanup();
+    cleanupPrep();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should not fetch from Contile if " +
+        "it's not enabled"
+    );
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+
+    NimbusFeatures.newtab.getVariable.reset();
+    NimbusFeatures.newtab.getVariable.returns(false);
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(fetchStub.notCalled, "TopSites.fetch was not called");
+    Assert.ok(!fetched);
+    Assert.equal(TopSites._contile.sites.length, 0);
+    await cleanup();
+    cleanupPrep();
+    fetchStub.restore();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should still return two tiles when Contile " +
+        "provides more than 2 tiles and filtering results in more than 2 tiles"
+    );
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+
+    NimbusFeatures.newtab.getVariable.reset();
+    NimbusFeatures.newtab.getVariable.onCall(0).returns(true);
+    NimbusFeatures.newtab.getVariable.onCall(1).returns(true);
+
+    fetchStub.resolves({
+      ok: true,
+      status: 200,
+      headers: new Map([
+        ["cache-control", "private, max-age=859, stale-if-error=10463"],
+      ]),
+      json: () =>
+        Promise.resolve({
+          tiles: [
+            {
+              url: "https://www.test.com",
+              image_url: "images/test-com.png",
+              click_url: "https://www.test-click.com",
+              impression_url: "https://www.test-impression.com",
+              name: "test",
+            },
+            {
+              url: "https://foo.com",
+              image_url: "images/foo-com.png",
+              click_url: "https://www.foo-click.com",
+              impression_url: "https://www.foo-impression.com",
+              name: "foo",
+            },
+            {
+              url: "https://bar.com",
+              image_url: "images/bar-com.png",
+              click_url: "https://www.bar-click.com",
+              impression_url: "https://www.bar-impression.com",
+              name: "bar",
+            },
+            {
+              url: "https://test1.com",
+              image_url: "images/test1-com.png",
+              click_url: "https://www.test1-click.com",
+              impression_url: "https://www.test1-impression.com",
+              name: "test1",
+            },
+            {
+              url: "https://test2.com",
+              image_url: "images/test2-com.png",
+              click_url: "https://www.test2-click.com",
+              impression_url: "https://www.test2-impression.com",
+              name: "test2",
+            },
+          ],
+        }),
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(fetched);
+    // Both "foo" and "bar" should be filtered
+    Assert.equal(TopSites._contile.sites.length, 2);
+    Assert.equal(TopSites._contile.sites[0].url, "https://www.test.com");
+    Assert.equal(TopSites._contile.sites[1].url, "https://test1.com");
+
+    await cleanup();
+    cleanupPrep();
+    fetchStub.restore();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should still return two tiles with " +
+        "replacement if the Nimbus variable was unset"
+    );
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+
+    NimbusFeatures.newtab.getVariable.reset();
+    NimbusFeatures.newtab.getVariable.onCall(0).returns(true);
+    NimbusFeatures.newtab.getVariable.onCall(1).returns(undefined);
+
+    fetchStub.resolves({
+      ok: true,
+      status: 200,
+      headers: new Map([
+        ["cache-control", "private, max-age=859, stale-if-error=10463"],
+      ]),
+      json: () =>
+        Promise.resolve({
+          tiles: [
+            {
+              url: "https://www.test.com",
+              image_url: "images/test-com.png",
+              click_url: "https://www.test-click.com",
+              impression_url: "https://www.test-impression.com",
+              name: "test",
+            },
+            {
+              url: "https://foo.com",
+              image_url: "images/foo-com.png",
+              click_url: "https://www.foo-click.com",
+              impression_url: "https://www.foo-impression.com",
+              name: "foo",
+            },
+            {
+              url: "https://test1.com",
+              image_url: "images/test1-com.png",
+              click_url: "https://www.test1-click.com",
+              impression_url: "https://www.test1-impression.com",
+              name: "test1",
+            },
+          ],
+        }),
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(fetched);
+    Assert.equal(TopSites._contile.sites.length, 2);
+    Assert.equal(TopSites._contile.sites[0].url, "https://www.test.com");
+    Assert.equal(TopSites._contile.sites[1].url, "https://test1.com");
+
+    await cleanup();
+    cleanupPrep();
+    fetchStub.restore();
+  }
+
+  {
+    info("TopSites._fetchSites should filter the blocked sponsors");
+    NimbusFeatures.newtab.getVariable.returns(true);
+
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+
+    fetchStub.resolves({
+      ok: true,
+      status: 200,
+      headers: new Map([
+        ["cache-control", "private, max-age=859, stale-if-error=10463"],
+      ]),
+      json: () =>
+        Promise.resolve({
+          tiles: [
+            {
+              url: "https://www.test.com",
+              image_url: "images/test-com.png",
+              click_url: "https://www.test-click.com",
+              impression_url: "https://www.test-impression.com",
+              name: "test",
+            },
+            {
+              url: "https://foo.com",
+              image_url: "images/foo-com.png",
+              click_url: "https://www.foo-click.com",
+              impression_url: "https://www.foo-impression.com",
+              name: "foo",
+            },
+            {
+              url: "https://bar.com",
+              image_url: "images/bar-com.png",
+              click_url: "https://www.bar-click.com",
+              impression_url: "https://www.bar-impression.com",
+              name: "bar",
+            },
+          ],
+        }),
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(fetched);
+    // Both "foo" and "bar" should be filtered
+    Assert.equal(TopSites._contile.sites.length, 1);
+    Assert.equal(TopSites._contile.sites[0].url, "https://www.test.com");
+    await cleanup();
+    cleanupPrep();
+    fetchStub.restore();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should return false when Contile returns " +
+        "with error status and no values are stored in cache prefs"
+    );
+    NimbusFeatures.newtab.getVariable.returns(true);
+    Services.prefs.setStringPref(CONTILE_CACHE_PREF, "[]");
+    Services.prefs.setIntPref(CONTILE_CACHE_LAST_FETCH_PREF, 0);
+
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+    fetchStub.resolves({
+      ok: false,
+      status: 500,
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(!fetched);
+    Assert.ok(!TopSites._contile.sites.length);
+    await cleanup();
+    cleanupPrep();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should return false when Contile " +
+        "returns with error status and cached tiles are expried"
+    );
+    NimbusFeatures.newtab.getVariable.returns(true);
+    Services.prefs.setStringPref(CONTILE_CACHE_PREF, "[]");
+    const THIRTY_MINUTES_AGO_IN_SECONDS =
+      Math.round(Date.now() / 1000) - 60 * 30;
+    Services.prefs.setIntPref(
+      CONTILE_CACHE_LAST_FETCH_PREF,
+      THIRTY_MINUTES_AGO_IN_SECONDS
+    );
+    Services.prefs.setIntPref(CONTILE_CACHE_VALID_FOR_SECONDS_PREF, 60 * 15);
+
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+
+    fetchStub.resolves({
+      ok: false,
+      status: 500,
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(!fetched);
+    Assert.ok(!TopSites._contile.sites.length);
+    await cleanup();
+    cleanupPrep();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should handle invalid payload " +
+        "properly from Contile"
+    );
+    NimbusFeatures.newtab.getVariable.returns(true);
+
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+    fetchStub.resolves({
+      ok: true,
+      status: 200,
+      json: () =>
+        Promise.resolve({
+          unknown: [],
+        }),
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(!fetched);
+    Assert.ok(!TopSites._contile.sites.length);
+    await cleanup();
+    cleanupPrep();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should handle empty payload properly " +
+        "from Contile"
+    );
+    NimbusFeatures.newtab.getVariable.returns(true);
+
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+    fetchStub.resolves({
+      ok: true,
+      status: 200,
+      headers: new Map([
+        ["cache-control", "private, max-age=859, stale-if-error=10463"],
+      ]),
+      json: () =>
+        Promise.resolve({
+          tiles: [],
+        }),
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(fetched);
+    Assert.ok(!TopSites._contile.sites.length);
+    await cleanup();
+    cleanupPrep();
+    fetchStub.restore();
+  }
+
+  {
+    info("TopSites._fetchSites should handle no content properly from Contile");
+    NimbusFeatures.newtab.getVariable.returns(true);
+
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+    fetchStub.resolves({ ok: true, status: 204 });
+
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(!fetched);
+    Assert.ok(!TopSites._contile.sites.length);
+    await cleanup();
+    cleanupPrep();
+    fetchStub.restore();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should set Caching Prefs after " +
+        "a successful request"
+    );
+    NimbusFeatures.newtab.getVariable.returns(true);
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+
+    let tiles = [
+      {
+        url: "https://www.test.com",
+        image_url: "images/test-com.png",
+        click_url: "https://www.test-click.com",
+        impression_url: "https://www.test-impression.com",
+        name: "test",
+      },
+      {
+        url: "https://www.test1.com",
+        image_url: "images/test1-com.png",
+        click_url: "https://www.test1-click.com",
+        impression_url: "https://www.test1-impression.com",
+        name: "test1",
+      },
+    ];
+    fetchStub.resolves({
+      ok: true,
+      status: 200,
+      headers: new Map([
+        ["cache-control", "private, max-age=859, stale-if-error=10463"],
+      ]),
+      json: () =>
+        Promise.resolve({
+          tiles,
+        }),
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+    Assert.ok(fetched);
+    Assert.equal(
+      Services.prefs.getStringPref(CONTILE_CACHE_PREF),
+      JSON.stringify(tiles)
+    );
+    Assert.equal(
+      Services.prefs.getIntPref(CONTILE_CACHE_VALID_FOR_SECONDS_PREF),
+      11322
+    );
+    await cleanup();
+    cleanupPrep();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should return cached valid tiles " +
+        "when Contile returns error status"
+    );
+    NimbusFeatures.newtab.getVariable.returns(true);
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+    let tiles = [
+      {
+        url: "https://www.test-cached.com",
+        image_url: "images/test-com.png",
+        click_url: "https://www.test-click.com",
+        impression_url: "https://www.test-impression.com",
+        name: "test",
+      },
+      {
+        url: "https://www.test1-cached.com",
+        image_url: "images/test1-com.png",
+        click_url: "https://www.test1-click.com",
+        impression_url: "https://www.test1-impression.com",
+        name: "test1",
+      },
+    ];
+
+    Services.prefs.setStringPref(CONTILE_CACHE_PREF, JSON.stringify(tiles));
+    Services.prefs.setIntPref(CONTILE_CACHE_VALID_FOR_SECONDS_PREF, 60 * 15);
+    Services.prefs.setIntPref(
+      CONTILE_CACHE_LAST_FETCH_PREF,
+      Math.round(Date.now() / 1000)
+    );
+
+    fetchStub.resolves({
+      status: 304,
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+    Assert.ok(fetched);
+    Assert.equal(TopSites._contile.sites.length, 2);
+    Assert.equal(TopSites._contile.sites[0].url, "https://www.test-cached.com");
+    Assert.equal(
+      TopSites._contile.sites[1].url,
+      "https://www.test1-cached.com"
+    );
+    await cleanup();
+    cleanupPrep();
+    fetchStub.restore();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should not be successful when contile " +
+        "returns an error and no valid tiles are cached"
+    );
+    NimbusFeatures.newtab.getVariable.returns(true);
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+    Services.prefs.setStringPref(CONTILE_CACHE_PREF, "[]");
+    Services.prefs.setIntPref(CONTILE_CACHE_VALID_FOR_SECONDS_PREF, 0);
+    Services.prefs.setIntPref(CONTILE_CACHE_LAST_FETCH_PREF, 0);
+
+    fetchStub.resolves({
+      status: 500,
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+    Assert.ok(!fetched);
+    await cleanup();
+    cleanupPrep();
+    fetchStub.restore();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should return cached valid tiles " +
+        "filtering blocked tiles when Contile returns error status"
+    );
+    NimbusFeatures.newtab.getVariable.returns(true);
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+
+    let tiles = [
+      {
+        url: "https://foo.com",
+        image_url: "images/foo-com.png",
+        click_url: "https://www.foo-click.com",
+        impression_url: "https://www.foo-impression.com",
+        name: "foo",
+      },
+      {
+        url: "https://www.test1-cached.com",
+        image_url: "images/test1-com.png",
+        click_url: "https://www.test1-click.com",
+        impression_url: "https://www.test1-impression.com",
+        name: "test1",
+      },
+    ];
+    Services.prefs.setStringPref(CONTILE_CACHE_PREF, JSON.stringify(tiles));
+    Services.prefs.setIntPref(CONTILE_CACHE_VALID_FOR_SECONDS_PREF, 60 * 15);
+    Services.prefs.setIntPref(
+      CONTILE_CACHE_LAST_FETCH_PREF,
+      Math.round(Date.now() / 1000)
+    );
+
+    fetchStub.resolves({
+      status: 304,
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+    Assert.ok(fetched);
+    Assert.equal(TopSites._contile.sites.length, 1);
+    Assert.equal(
+      TopSites._contile.sites[0].url,
+      "https://www.test1-cached.com"
+    );
+    await cleanup();
+    cleanupPrep();
+    fetchStub.restore();
+  }
+
+  {
+    info(
+      "TopSites._fetchSites should still return 3 tiles when nimbus " +
+        "variable overrides max num of sponsored contile tiles"
+    );
+    NimbusFeatures.newtab.getVariable.returns(true);
+    let cleanup = stubTopSites(sandbox);
+    let cleanupPrep = prepTopSites();
+
+    sandbox.stub(NimbusFeatures.pocketNewtab, "getVariable").returns(3);
+    fetchStub.resolves({
+      ok: true,
+      status: 200,
+      headers: new Map([
+        ["cache-control", "private, max-age=859, stale-if-error=10463"],
+      ]),
+      json: () =>
+        Promise.resolve({
+          tiles: [
+            {
+              url: "https://www.test.com",
+              image_url: "images/test-com.png",
+              click_url: "https://www.test-click.com",
+              impression_url: "https://www.test-impression.com",
+              name: "test",
+            },
+            {
+              url: "https://test1.com",
+              image_url: "images/test1-com.png",
+              click_url: "https://www.test1-click.com",
+              impression_url: "https://www.test1-impression.com",
+              name: "test1",
+            },
+            {
+              url: "https://test2.com",
+              image_url: "images/test2-com.png",
+              click_url: "https://www.test2-click.com",
+              impression_url: "https://www.test2-impression.com",
+              name: "test2",
+            },
+          ],
+        }),
+    });
+
+    let fetched = await TopSites._contile._fetchSites();
+
+    Assert.ok(fetched);
+    Assert.equal(TopSites._contile.sites.length, 3);
+    Assert.equal(TopSites._contile.sites[0].url, "https://www.test.com");
+    Assert.equal(TopSites._contile.sites[1].url, "https://test1.com");
+    Assert.equal(TopSites._contile.sites[2].url, "https://test2.com");
+    await cleanup();
+    cleanupPrep();
+    fetchStub.restore();
+  }
+
+  Services.prefs.clearUserPref(TOP_SITES_BLOCKED_SPONSORS_PREF);
+  sandbox.restore();
+});
diff --git a/browser/components/topsites/test/unit/xpcshell.toml b/browser/components/topsites/test/unit/xpcshell.toml
new file mode 100644
index 0000000000..98b0fc5360
--- /dev/null
+++ b/browser/components/topsites/test/unit/xpcshell.toml
@@ -0,0 +1,4 @@
+[DEFAULT]
+firefox-appdir = "browser"
+
+["test_top_sites.js"]