1 files changed, 256 insertions, 0 deletions
diff --git a/browser/modules/AboutNewTab.jsm b/browser/modules/AboutNewTab.jsm
new file mode 100644
index 0000000000..07d3d9b1bd
--- /dev/null
+++ b/browser/modules/AboutNewTab.jsm
@@ -0,0 +1,256 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const { AppConstants } = ChromeUtils.importESModule(
+  "resource://gre/modules/AppConstants.sys.mjs"
+);
+
+const { XPCOMUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/XPCOMUtils.sys.mjs"
+);
+
+const lazy = {};
+
+XPCOMUtils.defineLazyModuleGetters(lazy, {
+  ActivityStream: "resource://activity-stream/lib/ActivityStream.jsm",
+  ObjectUtils: "resource://gre/modules/ObjectUtils.jsm",
+});
+
+const ABOUT_URL = "about:newtab";
+const PREF_ACTIVITY_STREAM_DEBUG = "browser.newtabpage.activity-stream.debug";
+const TOPIC_APP_QUIT = "quit-application-granted";
+const BROWSER_READY_NOTIFICATION = "sessionstore-windows-restored";
+
+const AboutNewTab = {
+  QueryInterface: ChromeUtils.generateQI([
+    "nsIObserver",
+    "nsISupportsWeakReference",
+  ]),
+
+  // AboutNewTab
+  initialized: false,
+
+  willNotifyUser: false,
+
+  _activityStreamEnabled: false,
+  activityStream: null,
+  activityStreamDebug: false,
+
+  _cachedTopSites: null,
+
+  _newTabURL: ABOUT_URL,
+  _newTabURLOverridden: false,
+
+  /**
+   * init - Initializes an instance of Activity Stream if one doesn't exist already.
+   */
+  init() {
+    Services.obs.addObserver(this, TOPIC_APP_QUIT);
+    if (!AppConstants.RELEASE_OR_BETA) {
+      XPCOMUtils.defineLazyPreferenceGetter(
+        this,
+        "activityStreamDebug",
+        PREF_ACTIVITY_STREAM_DEBUG,
+        false,
+        () => {
+          this.notifyChange();
+        }
+      );
+    }
+
+    XPCOMUtils.defineLazyPreferenceGetter(
+      this,
+      "privilegedAboutProcessEnabled",
+      "browser.tabs.remote.separatePrivilegedContentProcess",
+      false,
+      () => {
+        this.notifyChange();
+      }
+    );
+
+    // More initialization happens here
+    this.toggleActivityStream(true);
+    this.initialized = true;
+
+    Services.obs.addObserver(this, BROWSER_READY_NOTIFICATION);
+  },
+
+  /**
+   * React to changes to the activity stream being enabled or not.
+   *
+   * This will only act if there is a change of state and if not overridden.
+   *
+   * @returns {Boolean} Returns if there has been a state change
+   *
+   * @param {Boolean}   stateEnabled    activity stream enabled state to set to
+   * @param {Boolean}   forceState      force state change
+   */
+  toggleActivityStream(stateEnabled, forceState = false) {
+    if (
+      !forceState &&
+      (this._newTabURLOverridden ||
+        stateEnabled === this._activityStreamEnabled)
+    ) {
+      // exit there is no change of state
+      return false;
+    }
+    if (stateEnabled) {
+      this._activityStreamEnabled = true;
+    } else {
+      this._activityStreamEnabled = false;
+    }
+
+    this._newTabURL = ABOUT_URL;
+    return true;
+  },
+
+  get newTabURL() {
+    return this._newTabURL;
+  },
+
+  set newTabURL(aNewTabURL) {
+    let newTabURL = aNewTabURL.trim();
+    if (newTabURL === ABOUT_URL) {
+      // avoid infinite redirects in case one sets the URL to about:newtab
+      this.resetNewTabURL();
+      return;
+    } else if (newTabURL === "") {
+      newTabURL = "about:blank";
+    }
+
+    this.toggleActivityStream(false);
+    this._newTabURL = newTabURL;
+    this._newTabURLOverridden = true;
+    this.notifyChange();
+  },
+
+  get newTabURLOverridden() {
+    return this._newTabURLOverridden;
+  },
+
+  get activityStreamEnabled() {
+    return this._activityStreamEnabled;
+  },
+
+  resetNewTabURL() {
+    this._newTabURLOverridden = false;
+    this._newTabURL = ABOUT_URL;
+    this.toggleActivityStream(true, true);
+    this.notifyChange();
+  },
+
+  notifyChange() {
+    Services.obs.notifyObservers(null, "newtab-url-changed", this._newTabURL);
+  },
+
+  /**
+   * onBrowserReady - Continues the initialization of Activity Stream after browser is ready.
+   */
+  onBrowserReady() {
+    if (this.activityStream && this.activityStream.initialized) {
+      return;
+    }
+
+    this.activityStream = new lazy.ActivityStream();
+    try {
+      this.activityStream.init();
+      this._subscribeToActivityStream();
+    } catch (e) {
+      console.error(e);
+    }
+  },
+
+  _subscribeToActivityStream() {
+    let unsubscribe = this.activityStream.store.subscribe(() => {
+      // If the top sites changed, broadcast "newtab-top-sites-changed". We
+      // ignore changes to the `screenshot` property in each site because
+      // screenshots are generated at times that are hard to predict and it ends
+      // up interfering with tests that rely on "newtab-top-sites-changed".
+      // Observers likely don't care about screenshots anyway.
+      let topSites = this.activityStream.store
+        .getState()
+        .TopSites.rows.map(site => {
+          site = { ...site };
+          delete site.screenshot;
+          return site;
+        });
+      if (!lazy.ObjectUtils.deepEqual(topSites, this._cachedTopSites)) {
+        this._cachedTopSites = topSites;
+        Services.obs.notifyObservers(null, "newtab-top-sites-changed");
+      }
+    });
+    this._unsubscribeFromActivityStream = () => {
+      try {
+        unsubscribe();
+      } catch (e) {
+        console.error(e);
+      }
+    };
+  },
+
+  /**
+   * uninit - Uninitializes Activity Stream if it exists.
+   */
+  uninit() {
+    if (this.activityStream) {
+      this._unsubscribeFromActivityStream?.();
+      this.activityStream.uninit();
+      this.activityStream = null;
+    }
+
+    this.initialized = false;
+  },
+
+  getTopSites() {
+    return this.activityStream
+      ? this.activityStream.store.getState().TopSites.rows
+      : [];
+  },
+
+  _alreadyRecordedTopsitesPainted: false,
+  _nonDefaultStartup: false,
+
+  noteNonDefaultStartup() {
+    this._nonDefaultStartup = true;
+  },
+
+  maybeRecordTopsitesPainted(timestamp) {
+    if (this._alreadyRecordedTopsitesPainted || this._nonDefaultStartup) {
+      return;
+    }
+
+    const SCALAR_KEY = "timestamps.about_home_topsites_first_paint";
+
+    let startupInfo = Services.startup.getStartupInfo();
+    let processStartTs = startupInfo.process.getTime();
+    let delta = Math.round(timestamp - processStartTs);
+    Services.telemetry.scalarSet(SCALAR_KEY, delta);
+    ChromeUtils.addProfilerMarker("aboutHomeTopsitesFirstPaint");
+    this._alreadyRecordedTopsitesPainted = true;
+  },
+
+  // nsIObserver implementation
+
+  observe(subject, topic, data) {
+    switch (topic) {
+      case TOPIC_APP_QUIT: {
+        // We defer to this to the next tick of the event loop since the
+        // AboutHomeStartupCache might want to read from the ActivityStream
+        // store during TOPIC_APP_QUIT.
+        Services.tm.dispatchToMainThread(() => this.uninit());
+        break;
+      }
+      case BROWSER_READY_NOTIFICATION: {
+        Services.obs.removeObserver(this, BROWSER_READY_NOTIFICATION);
+        // Avoid running synchronously during this event that's used for timing
+        Services.tm.dispatchToMainThread(() => this.onBrowserReady());
+        break;
+      }
+    }
+  },
+};
+
+var EXPORTED_SYMBOLS = ["AboutNewTab"];