Bug 1882171 - Stub out the beginnings of the BackupService. r=mossop,kpatenio,fchasen

This creates a new BackupService component that lives under browser/components/backup.
It doesn't do much yet, except allow itself to be instantiated (which currently occurs
using the idle scheduler in BrowserGlue) - but it does set us up to have docs, SphinxJS
exporting for JSDoc, linting, etc.

Differential Revision: https://phabricator.services.mozilla.com/D202753

browser/app/profile/firefox.js

@@ -3029,3 +3029,5 @@ pref("browser.mailto.dualPrompt.os", false);
 // When visiting a site which uses registerProtocolHandler: Ask the user to set Firefox as
 // default mailto handler.
 pref("browser.mailto.prompt.os", true);
+
+pref("browser.backup.enabled", false);

browser/components/BrowserGlue.sys.mjs

@@ -17,6 +17,7 @@ ChromeUtils.defineESModuleGetters(lazy, {
   AddonManager: "resource://gre/modules/AddonManager.sys.mjs",
   AppMenuNotifications: "resource://gre/modules/AppMenuNotifications.sys.mjs",
   AsyncShutdown: "resource://gre/modules/AsyncShutdown.sys.mjs",
+  BackupService: "resource:///modules/backup/BackupService.sys.mjs",
   Blocklist: "resource://gre/modules/Blocklist.sys.mjs",
   BookmarkHTMLUtils: "resource://gre/modules/BookmarkHTMLUtils.sys.mjs",
   BookmarkJSONUtils: "resource://gre/modules/BookmarkJSONUtils.sys.mjs",
@@ -3166,6 +3167,14 @@ BrowserGlue.prototype = {
         },
       },
 
+      {
+        name: "BackupService initialization",
+        condition: Services.prefs.getBoolPref("browser.backup.enabled", false),
+        task: () => {
+          lazy.BackupService.init();
+        },
+      },
+
       {
         name: "browser-startup-idle-tasks-finished",
         task: () => {

browser/components/backup/.eslintrc.js

@@ -0,0 +1,9 @@
+/* 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";
+
+module.exports = {
+  extends: ["plugin:mozilla/require-jsdoc"],
+};

browser/components/backup/BackupService.sys.mjs

@@ -0,0 +1,48 @@
+/* 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/. */
+
+const lazy = {};
+
+ChromeUtils.defineLazyGetter(lazy, "logConsole", function () {
+  return console.createInstance({
+    prefix: "BackupService",
+    maxLogLevel: Services.prefs.getBoolPref("browser.backup.log", false)
+      ? "Debug"
+      : "Warn",
+  });
+});
+
+/**
+ * The BackupService class orchestrates the scheduling and creation of profile
+ * backups. It also does most of the heavy lifting for the restoration of a
+ * profile backup.
+ */
+export class BackupService {
+  /**
+   * The BackupService singleton instance.
+   *
+   * @static
+   * @type {BackupService|null}
+   */
+  static #instance = null;
+
+  /**
+   * Returns a reference to a BackupService singleton. If this is the first time
+   * that this getter is accessed, this causes the BackupService singleton to be
+   * be instantiated.
+   *
+   * @static
+   * @type {BackupService}
+   */
+  static init() {
+    if (this.#instance) {
+      return this.#instance;
+    }
+    return (this.#instance = new BackupService());
+  }
+
+  constructor() {
+    lazy.logConsole.debug("Instantiated");
+  }
+}

browser/components/backup/docs/backup-service.rst

@@ -0,0 +1,8 @@
+========================
+Backup Service Reference
+========================
+
+.. autoattribute:: BackupService##instance
+.. js:autoclass:: BackupService
+  :members:
+  :private-members:

browser/components/backup/docs/index.rst

@@ -0,0 +1,13 @@
+.. _components/backup:
+
+================
+Backup Component
+================
+
+The Backup Component is responsible for creating backups of user profile data
+into a single file that can be easily restored from.
+
+.. toctree::
+   :maxdepth: 3
+
+   backup-service

browser/components/backup/moz.build

@@ -0,0 +1,11 @@
+# -*- 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/.
+
+SPHINX_TREES["docs"] = "docs"
+
+EXTRA_JS_MODULES.backup += [
+    "BackupService.sys.mjs",
+]

browser/components/moz.build

@@ -32,6 +32,7 @@ DIRS += [
     "aboutwelcome",
     "asrouter",
     "attribution",
+    "backup",
     "contentanalysis",
     "contextualidentity",
     "customizableui",

browser/docs/index.rst

@@ -31,3 +31,4 @@ This is the nascent documentation of the Firefox front-end code.
    components/storybook/docs/README.other-widgets.stories
    components/storybook/docs/README.lit-guide.stories
    components/storybook/docs/README.xul-and-html.stories
+   components/backup/docs/index

docs/conf.py

@@ -54,6 +54,7 @@ extensions = [
 # When adding more paths to this list, please ensure that they are not
 # excluded from valid-jsdoc in the top-level .eslintrc.js.
 js_source_path = [
+    "../browser/components/backup",
     "../browser/components/extensions",
     "../browser/components/migration",
     "../browser/components/migration/content",