Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

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

1 files changed, 1601 insertions, 0 deletions

diff --git a/browser/components/urlbar/UrlbarPrefs.sys.mjs b/browser/components/urlbar/UrlbarPrefs.sys.mjs
new file mode 100644
index 0000000000..a8addd7e79
--- /dev/null
+++ b/browser/components/urlbar/UrlbarPrefs.sys.mjs
@@ -0,0 +1,1601 @@
+/* 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/. */
+
+/**
+ * This module exports the UrlbarPrefs singleton, which manages preferences for
+ * the urlbar. It also provides access to urlbar Nimbus variables as if they are
+ * preferences, but only for variables with fallback prefs.
+ */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  NimbusFeatures: "resource://nimbus/ExperimentAPI.sys.mjs",
+  Region: "resource://gre/modules/Region.sys.mjs",
+  TelemetryEnvironment: "resource://gre/modules/TelemetryEnvironment.sys.mjs",
+  UrlbarUtils: "resource:///modules/UrlbarUtils.sys.mjs",
+});
+
+const PREF_URLBAR_BRANCH = "browser.urlbar.";
+
+// Prefs are defined as [pref name, default value] or [pref name, [default
+// value, type]].  In the former case, the getter method name is inferred from
+// the typeof the default value.
+//
+// NOTE: Don't name prefs (relative to the `browser.urlbar` branch) the same as
+// Nimbus urlbar features. Doing so would cause a name collision because pref
+// names and Nimbus feature names are both kept as keys in UrlbarPref's map. For
+// a list of Nimbus features, see toolkit/components/nimbus/FeatureManifest.yaml.
+const PREF_URLBAR_DEFAULTS = new Map([
+  // Whether we announce to screen readers when tab-to-search results are
+  // inserted.
+  ["accessibility.tabToSearch.announceResults", true],
+
+  // Feature gate pref for addon suggestions in the urlbar.
+  ["addons.featureGate", false],
+
+  // The number of times the user has clicked the "Show less frequently" command
+  // for addon suggestions.
+  ["addons.showLessFrequentlyCount", 0],
+
+  // "Autofill" is the name of the feature that automatically completes domains
+  // and URLs that the user has visited as the user is typing them in the urlbar
+  // textbox.  If false, autofill will be disabled.
+  ["autoFill", true],
+
+  // Whether enabling adaptive history autofill. This pref is a fallback for the
+  // Nimbus variable `autoFillAdaptiveHistoryEnabled`.
+  ["autoFill.adaptiveHistory.enabled", false],
+
+  // Minimum char length of the user's search string to enable adaptive history
+  // autofill. This pref is a fallback for the Nimbus variable
+  // `autoFillAdaptiveHistoryMinCharsThreshold`.
+  ["autoFill.adaptiveHistory.minCharsThreshold", 0],
+
+  // Threshold for use count of input history that we handle as adaptive history
+  // autofill. If the use count is this value or more, it will be a candidate.
+  // Set the threshold to not be candidate the input history passed approximately
+  // 30 days since user input it as the default.
+  ["autoFill.adaptiveHistory.useCountThreshold", [0.47, "float"]],
+
+  // If true, the domains of the user's installed search engines will be
+  // autofilled even if the user hasn't actually visited them.
+  ["autoFill.searchEngines", false],
+
+  // Affects the frecency threshold of the autofill algorithm.  The threshold is
+  // the mean of all origin frecencies plus one standard deviation multiplied by
+  // this value.  See UrlbarProviderPlaces.
+  ["autoFill.stddevMultiplier", [0.0, "float"]],
+
+  // Whether best match results can be blocked. This pref is a fallback for the
+  // Nimbus variable `bestMatchBlockingEnabled`.
+  ["bestMatch.blockingEnabled", true],
+
+  // Whether the best match feature is enabled.
+  ["bestMatch.enabled", true],
+
+  // Whether to show a link for using the search functionality provided by the
+  // active view if the the view utilizes OpenSearch.
+  ["contextualSearch.enabled", false],
+
+  // Whether using `ctrl` when hitting return/enter in the URL bar
+  // (or clicking 'go') should prefix 'www.' and suffix
+  // browser.fixup.alternate.suffix to the URL bar value prior to
+  // navigating.
+  ["ctrlCanonizesURLs", true],
+
+  // Whether copying the entire URL from the location bar will put a human
+  // readable (percent-decoded) URL on the clipboard.
+  ["decodeURLsOnCopy", false],
+
+  // The amount of time (ms) to wait after the user has stopped typing before
+  // fetching results.  However, we ignore this for the very first result (the
+  // "heuristic" result).  We fetch it as fast as possible.
+  ["delay", 50],
+
+  // Some performance tests disable this because extending the urlbar needs
+  // layout information that we can't get before the first paint. (Or we could
+  // but this would mean flushing layout.)
+  ["disableExtendForTests", false],
+
+  // Ensure we use trailing dots for DNS lookups for single words that could
+  // be hosts.
+  ["dnsResolveFullyQualifiedNames", true],
+
+  // Controls when to DNS resolve single word search strings, after they were
+  // searched for. If the string is resolved as a valid host, show a
+  // "Did you mean to go to 'host'" prompt.
+  // 0 - never resolve; 1 - use heuristics (default); 2 - always resolve
+  ["dnsResolveSingleWordsAfterSearch", 0],
+
+  // Whether telemetry events should be recorded.
+  ["eventTelemetry.enabled", false],
+
+  // Whether we expand the font size when when the urlbar is
+  // focused.
+  ["experimental.expandTextOnFocus", false],
+
+  // Whether the heuristic result is hidden.
+  ["experimental.hideHeuristic", false],
+
+  // Whether the urlbar displays a permanent search button.
+  ["experimental.searchButton", false],
+
+  // Comma-separated list of `source.providers` combinations, that are used to
+  // determine if an exposure event should be fired. This can be set by a
+  // Nimbus variable and is expected to be set via nimbus experiment
+  // configuration.
+  ["exposureResults", ""],
+
+  // When we send events to (privileged) extensions (urlbar API), we wait this
+  // amount of time in milliseconds for them to respond before timing out.
+  ["extension.timeout", 400],
+
+  // When we send events to extensions that use the omnibox API, we wait this
+  // amount of time in milliseconds for them to respond before timing out.
+  ["extension.omnibox.timeout", 3000],
+
+  // When true, `javascript:` URLs are not included in search results.
+  ["filter.javascript", true],
+
+  // Applies URL highlighting and other styling to the text in the urlbar input.
+  ["formatting.enabled", true],
+
+  // Interval time until taking pause impression telemetry.
+  ["searchEngagementTelemetry.pauseImpressionIntervalMs", 1000],
+
+  // Boolean to determine if the providers defined in `exposureResults`
+  // should be displayed in search results. This can be set by a
+  // Nimbus variable and is expected to be set via nimbus experiment
+  // configuration. For the control branch of an experiment this would be
+  // false and true for the treatment.
+  ["showExposureResults", false],
+
+  // Whether Firefox Suggest group labels are shown in the urlbar view in en-*
+  // locales. Labels are not shown in other locales but likely will be in the
+  // future.
+  ["groupLabels.enabled", true],
+
+  // Whether the results panel should be kept open during IME composition.
+  ["keepPanelOpenDuringImeComposition", false],
+
+  // As a user privacy measure, don't fetch results from remote services for
+  // searches that start by pasting a string longer than this. The pref name
+  // indicates search suggestions, but this is used for all remote results.
+  ["maxCharsForSearchSuggestions", 100],
+
+  // The maximum number of form history results to include.
+  ["maxHistoricalSearchSuggestions", 0],
+
+  // The maximum number of results in the urlbar popup.
+  ["maxRichResults", 10],
+
+  // Comma-separated list of client variants to send to Merino
+  ["merino.clientVariants", ""],
+
+  // Whether Merino is enabled as a quick suggest source.
+  ["merino.enabled", false],
+
+  // The Merino endpoint URL, not including parameters.
+  ["merino.endpointURL", "https://merino.services.mozilla.com/api/v1/suggest"],
+
+  // Comma-separated list of providers to request from Merino
+  ["merino.providers", ""],
+
+  // Timeout for Merino fetches (ms).
+  ["merino.timeoutMs", 200],
+
+  // Whether addresses and search results typed into the address bar
+  // should be opened in new tabs by default.
+  ["openintab", false],
+
+  // When true, URLs in the user's history that look like search result pages
+  // are styled to look like search engine results instead of the usual history
+  // results.
+  ["restyleSearches", false],
+
+  // If true, we show tail suggestions when available.
+  ["richSuggestions.tail", true],
+
+  // Hidden pref. Disables checks that prevent search tips being shown, thus
+  // showing them every time the newtab page or the default search engine
+  // homepage is opened.
+  ["searchTips.test.ignoreShowLimits", false],
+
+  // Whether to show each local search shortcut button in the view.
+  ["shortcuts.bookmarks", true],
+  ["shortcuts.tabs", true],
+  ["shortcuts.history", true],
+  ["shortcuts.quickactions", false],
+
+  // Whether to show search suggestions before general results.
+  ["showSearchSuggestionsFirst", true],
+
+  // Global toggle for whether the show search terms feature
+  // can be used at all, and enabled/disabled by the user.
+  ["showSearchTerms.featureGate", false],
+
+  // If true, show the search term in the Urlbar while on
+  // a default search engine results page.
+  ["showSearchTerms.enabled", true],
+
+  // Whether speculative connections should be enabled.
+  ["speculativeConnect.enabled", true],
+
+  // When `bestMatch.enabled` is true, this controls whether results will
+  // include best matches.
+  ["suggest.bestmatch", true],
+
+  // Whether results will include the user's bookmarks.
+  ["suggest.bookmark", true],
+
+  // Whether results will include a calculator.
+  ["suggest.calculator", false],
+
+  // Whether results will include search engines (e.g. tab-to-search).
+  ["suggest.engines", true],
+
+  // Whether results will include the user's history.
+  ["suggest.history", true],
+
+  // Whether results will include switch-to-tab results.
+  ["suggest.openpage", true],
+
+  // Whether results will include synced tab results. The syncing of open tabs
+  // must also be enabled, from Sync preferences.
+  ["suggest.remotetab", true],
+
+  // Whether results will include QuickActions in the default search mode.
+  ["suggest.quickactions", false],
+
+  // If disabled, QuickActions will not be included in either the default search
+  // mode or the QuickActions search mode.
+  ["quickactions.enabled", false],
+
+  // Whether we show the Actions section in about:preferences.
+  ["quickactions.showPrefs", false],
+
+  // Whether we will match QuickActions within a phrase and not only a prefix.
+  ["quickactions.matchInPhrase", true],
+
+  // Show multiple actions in a random order.
+  ["quickactions.randomOrderActions", false],
+
+  // The minumum amount of characters required for the user to input before
+  // matching actions. Setting this to 0 will show the actions in the
+  // zero prefix state.
+  ["quickactions.minimumSearchString", 3],
+
+  // Whether results will include non-sponsored quick suggest suggestions.
+  ["suggest.quicksuggest.nonsponsored", false],
+
+  // Whether results will include sponsored quick suggest suggestions.
+  ["suggest.quicksuggest.sponsored", false],
+
+  // If `browser.urlbar.addons.featureGate` is true, this controls whether
+  // addon suggestions are turned on.
+  ["suggest.addons", true],
+
+  // Whether results will include search suggestions.
+  ["suggest.searches", false],
+
+  // Whether results will include top sites and the view will open on focus.
+  ["suggest.topsites", true],
+
+  // If `browser.urlbar.weather.featureGate` is true, this controls whether
+  // weather suggestions are turned on.
+  ["suggest.weather", true],
+
+  // JSON'ed array of blocked quick suggest URL digests.
+  ["quicksuggest.blockedDigests", ""],
+
+  // Whether the usual non-best-match quick suggest results can be blocked. This
+  // pref is a fallback for the Nimbus variable `quickSuggestBlockingEnabled`.
+  ["quicksuggest.blockingEnabled", true],
+
+  // Global toggle for whether the quick suggest feature is enabled, i.e.,
+  // sponsored and recommended results related to the user's search string.
+  ["quicksuggest.enabled", false],
+
+  // Whether non-sponsored quick suggest results are subject to impression
+  // frequency caps. This pref is a fallback for the Nimbus variable
+  // `quickSuggestImpressionCapsNonSponsoredEnabled`.
+  ["quicksuggest.impressionCaps.nonSponsoredEnabled", false],
+
+  // Whether sponsored quick suggest results are subject to impression frequency
+  // caps. This pref is a fallback for the Nimbus variable
+  // `quickSuggestImpressionCapsSponsoredEnabled`.
+  ["quicksuggest.impressionCaps.sponsoredEnabled", false],
+
+  // JSON'ed object of quick suggest impression stats. Used for implementing
+  // impression frequency caps for quick suggest suggestions.
+  ["quicksuggest.impressionCaps.stats", ""],
+
+  // The user's response to the Firefox Suggest online opt-in dialog.
+  ["quicksuggest.onboardingDialogChoice", ""],
+
+  // If the user has gone through a quick suggest prefs migration, then this
+  // pref will have a user-branch value that records the latest prefs version.
+  // Version changelog:
+  //
+  // 0: (Unversioned) When `suggest.quicksuggest` is false, all quick suggest
+  //    results are disabled and `suggest.quicksuggest.sponsored` is ignored. To
+  //    show sponsored suggestions, both prefs must be true.
+  //
+  // 1: `suggest.quicksuggest` is removed, `suggest.quicksuggest.nonsponsored`
+  //    is introduced. `suggest.quicksuggest.nonsponsored` and
+  //    `suggest.quicksuggest.sponsored` are independent:
+  //    `suggest.quicksuggest.nonsponsored` controls non-sponsored results and
+  //    `suggest.quicksuggest.sponsored` controls sponsored results.
+  //    `quicksuggest.dataCollection.enabled` is introduced.
+  //
+  // 2: For online, the defaults for `suggest.quicksuggest.nonsponsored` and
+  //    `suggest.quicksuggest.sponsored` are true. Previously they were false.
+  ["quicksuggest.migrationVersion", 0],
+
+  // Whether Remote Settings is enabled as a quick suggest source.
+  ["quicksuggest.remoteSettings.enabled", true],
+
+  // The Firefox Suggest scenario in which the user is enrolled. This is set
+  // when the scenario is updated (see `updateFirefoxSuggestScenario`) and is
+  // not a pref the user should set. Once initialized, its value is one of:
+  // "history", "offline", "online"
+  ["quicksuggest.scenario", ""],
+
+  // Whether the user has opted in to data collection for quick suggest.
+  ["quicksuggest.dataCollection.enabled", false],
+
+  // The version of dialog user saw.
+  ["quicksuggest.onboardingDialogVersion", ""],
+
+  // Whether to show the quick suggest onboarding dialog.
+  ["quicksuggest.shouldShowOnboardingDialog", true],
+
+  // Whether the user has seen the onboarding dialog.
+  ["quicksuggest.showedOnboardingDialog", false],
+
+  // Count the restarts before showing the onboarding dialog.
+  ["quicksuggest.seenRestarts", 0],
+
+  // Whether quick suggest results can be shown in position specified in the
+  // suggestions.
+  ["quicksuggest.allowPositionInSuggestions", true],
+
+  // Enable three-dot options button and menu for eligible results.
+  ["resultMenu", true],
+
+  // Allow the result menu button to be reached with the Tab key.
+  ["resultMenu.keyboardAccessible", true],
+
+  // When using switch to tabs, if set to true this will move the tab into the
+  // active window.
+  ["switchTabs.adoptIntoActiveWindow", false],
+
+  // The number of remaining times the user can interact with tab-to-search
+  // onboarding results before we stop showing them.
+  ["tabToSearch.onboard.interactionsLeft", 3],
+
+  // The number of times the user has been shown the onboarding search tip.
+  ["tipShownCount.searchTip_onboard", 0],
+
+  // The number of times the user has been shown the urlbar persisted search tip.
+  ["tipShownCount.searchTip_persist", 0],
+
+  // The number of times the user has been shown the redirect search tip.
+  ["tipShownCount.searchTip_redirect", 0],
+
+  // Remove redundant portions from URLs.
+  ["trimURLs", true],
+
+  // If true, top sites may include sponsored ones.
+  ["sponsoredTopSites", false],
+
+  // Whether unit conversion is enabled.
+  ["unitConversion.enabled", false],
+
+  // The index where we show unit conversion results.
+  ["unitConversion.suggestedIndex", 1],
+
+  // Results will include a built-in set of popular domains when this is true.
+  ["usepreloadedtopurls.enabled", false],
+
+  // After this many days from the profile creation date, the built-in set of
+  // popular domains will no longer be included in the results.
+  ["usepreloadedtopurls.expire_days", 14],
+
+  // Controls the empty search behavior in Search Mode:
+  //  0 - Show nothing
+  //  1 - Show search history
+  //  2 - Show search and browsing history
+  ["update2.emptySearchBehavior", 0],
+
+  // Feature gate pref for weather suggestions in the urlbar.
+  ["weather.featureGate", false],
+
+  // When false, the weather suggestion will not be fetched when a VPN is
+  // detected. When true, it will be fetched anyway.
+  ["weather.ignoreVPN", false],
+
+  // The minimum prefix length of a weather keyword the user must type to
+  // trigger the suggestion. 0 means the min length should be taken from Nimbus
+  // or remote settings.
+  ["weather.minKeywordLength", 0],
+
+  // Feature gate pref for trending suggestions in the urlbar.
+  ["trending.featureGate", false],
+
+  // Whether to only show trending results when the urlbar is in search
+  // mode or when the user initially opens the urlbar without selecting
+  // an engine.
+  ["trending.requireSearchMode", true],
+
+  // The maximum number of trending results to show in search mode.
+  ["trending.maxResultsSearchMode", 10],
+
+  // The maximum number of trending results to show while not in search mode.
+  ["trending.maxResultsNoSearchMode", 10],
+
+  // Feature gate pref for rich suggestions being shown in the urlbar.
+  ["richSuggestions.featureGate", false],
+]);
+
+const PREF_OTHER_DEFAULTS = new Map([
+  ["browser.fixup.dns_first_for_single_words", false],
+  ["browser.search.suggest.enabled", true],
+  ["browser.search.suggest.enabled.private", false],
+  ["browser.search.widget.inNavBar", false],
+  ["keyword.enabled", true],
+  ["ui.popup.disable_autohide", false],
+]);
+
+// Default values for Nimbus urlbar variables that do not have fallback prefs.
+// Variables with fallback prefs do not need to be defined here because their
+// defaults are the values of their fallbacks.
+const NIMBUS_DEFAULTS = {
+  addonsShowLessFrequentlyCap: 0,
+  addonsUITreatment: "a",
+  experimentType: "",
+  isBestMatchExperiment: false,
+  quickSuggestRemoteSettingsDataType: "data",
+  recordNavigationalSuggestionTelemetry: false,
+  weatherKeywords: null,
+  weatherKeywordsMinimumLength: 0,
+  weatherKeywordsMinimumLengthCap: 0,
+};
+
+// Maps preferences under browser.urlbar.suggest to behavior names, as defined
+// in mozIPlacesAutoComplete.
+const SUGGEST_PREF_TO_BEHAVIOR = {
+  history: "history",
+  bookmark: "bookmark",
+  openpage: "openpage",
+  searches: "search",
+};
+
+const PREF_TYPES = new Map([
+  ["boolean", "Bool"],
+  ["float", "Float"],
+  ["number", "Int"],
+  ["string", "Char"],
+]);
+
+/**
+ * Builds the standard result groups and returns the root group.  Result
+ * groups determine the composition of results in the muxer, i.e., how they're
+ * grouped and sorted.  Each group is an object that looks like this:
+ *
+ * {
+ *   {UrlbarUtils.RESULT_GROUP} [group]
+ *     This is defined only on groups without children, and it determines the
+ *     result group that the group will contain.
+ *   {number} [maxResultCount]
+ *     An optional maximum number of results the group can contain.  If it's
+ *     not defined and the parent group does not define `flexChildren: true`,
+ *     then the max is the parent's max.  If the parent group defines
+ *     `flexChildren: true`, then `maxResultCount` is ignored.
+ *   {boolean} [flexChildren]
+ *     If true, then child groups are "flexed", similar to flex in HTML.  Each
+ *     child group should define the `flex` property (or, if they don't, `flex`
+ *     is assumed to be zero).  `flex` is a number that defines the ratio of a
+ *     child's result count to the total result count of all children.  More
+ *     specifically, `flex: X` on a child means that the initial maximum result
+ *     count of the child is `parentMaxResultCount * (X / N)`, where `N` is the
+ *     sum of the `flex` values of all children.  If there are any child groups
+ *     that cannot be completely filled, then the muxer will attempt to overfill
+ *     the children that were completely filled, while still respecting their
+ *     relative `flex` values.
+ *   {number} [flex]
+ *     The flex value of the group.  This should be defined only on groups
+ *     where the parent defines `flexChildren: true`.  See `flexChildren` for a
+ *     discussion of flex.
+ *   {array} [children]
+ *     An array of child group objects.
+ * }
+ *
+ * @param {boolean} showSearchSuggestionsFirst
+ *   If true, the suggestions group will come before the general group.
+ * @returns {object}
+ *   The root group.
+ */
+function makeResultGroups({ showSearchSuggestionsFirst }) {
+  let rootGroup = {
+    children: [
+      // heuristic
+      {
+        maxResultCount: 1,
+        children: [
+          { group: lazy.UrlbarUtils.RESULT_GROUP.HEURISTIC_TEST },
+          { group: lazy.UrlbarUtils.RESULT_GROUP.HEURISTIC_EXTENSION },
+          { group: lazy.UrlbarUtils.RESULT_GROUP.HEURISTIC_SEARCH_TIP },
+          { group: lazy.UrlbarUtils.RESULT_GROUP.HEURISTIC_OMNIBOX },
+          { group: lazy.UrlbarUtils.RESULT_GROUP.HEURISTIC_ENGINE_ALIAS },
+          { group: lazy.UrlbarUtils.RESULT_GROUP.HEURISTIC_BOOKMARK_KEYWORD },
+          { group: lazy.UrlbarUtils.RESULT_GROUP.HEURISTIC_AUTOFILL },
+          { group: lazy.UrlbarUtils.RESULT_GROUP.HEURISTIC_PRELOADED },
+          { group: lazy.UrlbarUtils.RESULT_GROUP.HEURISTIC_TOKEN_ALIAS_ENGINE },
+          { group: lazy.UrlbarUtils.RESULT_GROUP.HEURISTIC_HISTORY_URL },
+          { group: lazy.UrlbarUtils.RESULT_GROUP.HEURISTIC_FALLBACK },
+        ],
+      },
+      // extensions using the omnibox API
+      {
+        group: lazy.UrlbarUtils.RESULT_GROUP.OMNIBOX,
+      },
+    ],
+  };
+
+  // Prepare the parent group for suggestions and general.
+  let mainGroup = {
+    flexChildren: true,
+    children: [
+      // suggestions
+      {
+        children: [
+          {
+            flexChildren: true,
+            children: [
+              {
+                // If `maxHistoricalSearchSuggestions` == 0, the muxer forces
+                // `maxResultCount` to be zero and flex is ignored, per query.
+                flex: 2,
+                group: lazy.UrlbarUtils.RESULT_GROUP.FORM_HISTORY,
+              },
+              {
+                flex: 4,
+                group: lazy.UrlbarUtils.RESULT_GROUP.REMOTE_SUGGESTION,
+              },
+            ],
+          },
+          {
+            group: lazy.UrlbarUtils.RESULT_GROUP.TAIL_SUGGESTION,
+          },
+        ],
+      },
+      // general
+      {
+        group: lazy.UrlbarUtils.RESULT_GROUP.GENERAL_PARENT,
+        children: [
+          {
+            availableSpan: 3,
+            group: lazy.UrlbarUtils.RESULT_GROUP.INPUT_HISTORY,
+          },
+          {
+            flexChildren: true,
+            children: [
+              {
+                flex: 1,
+                group: lazy.UrlbarUtils.RESULT_GROUP.REMOTE_TAB,
+              },
+              {
+                flex: 2,
+                group: lazy.UrlbarUtils.RESULT_GROUP.GENERAL,
+              },
+              {
+                // We show relatively many about-page results because they're
+                // only added for queries starting with "about:".
+                flex: 2,
+                group: lazy.UrlbarUtils.RESULT_GROUP.ABOUT_PAGES,
+              },
+              {
+                flex: 1,
+                group: lazy.UrlbarUtils.RESULT_GROUP.PRELOADED,
+              },
+            ],
+          },
+          {
+            group: lazy.UrlbarUtils.RESULT_GROUP.INPUT_HISTORY,
+          },
+        ],
+      },
+    ],
+  };
+  if (!showSearchSuggestionsFirst) {
+    mainGroup.children.reverse();
+  }
+  mainGroup.children[0].flex = 2;
+  mainGroup.children[1].flex = 1;
+  rootGroup.children.push(mainGroup);
+
+  return rootGroup;
+}
+
+/**
+ * Preferences class.  The exported object is a singleton instance.
+ */
+class Preferences {
+  /**
+   * Constructor
+   */
+  constructor() {
+    this._map = new Map();
+    this.QueryInterface = ChromeUtils.generateQI([
+      "nsIObserver",
+      "nsISupportsWeakReference",
+    ]);
+
+    Services.prefs.addObserver(PREF_URLBAR_BRANCH, this, true);
+    for (let pref of PREF_OTHER_DEFAULTS.keys()) {
+      Services.prefs.addObserver(pref, this, true);
+    }
+    this._observerWeakRefs = [];
+    this.addObserver(this);
+
+    // These prefs control the value of the shouldHandOffToSearchMode pref. They
+    // are exposed as a class variable so UrlbarPrefs observers can watch for
+    // changes in these prefs.
+    this.shouldHandOffToSearchModePrefs = [
+      "keyword.enabled",
+      "suggest.searches",
+    ];
+
+    // This is resolved when the first update to the Firefox Suggest scenario
+    // (on startup) finishes.
+    this._firefoxSuggestScenarioStartupPromise = new Promise(
+      resolve => (this._resolveFirefoxSuggestScenarioStartupPromise = resolve)
+    );
+
+    // This is set to true when we update the Firefox Suggest scenario to
+    // prevent re-entry due to pref observers.
+    this._updatingFirefoxSuggestScenario = false;
+
+    lazy.NimbusFeatures.urlbar.onUpdate(() => this._onNimbusUpdate());
+  }
+
+  /**
+   * Returns the value for the preference with the given name.
+   * For preferences in the "browser.urlbar."" branch, the passed-in name
+   * should be relative to the branch. It's also possible to get prefs from the
+   * PREF_OTHER_DEFAULTS Map, specifying their full name.
+   *
+   * @param {string} pref
+   *        The name of the preference to get.
+   * @returns {*} The preference value.
+   */
+  get(pref) {
+    let value = this._map.get(pref);
+    if (value === undefined) {
+      value = this._getPrefValue(pref);
+      this._map.set(pref, value);
+    }
+    return value;
+  }
+
+  /**
+   * Sets the value for the preference with the given name.
+   * For preferences in the "browser.urlbar."" branch, the passed-in name
+   * should be relative to the branch. It's also possible to set prefs from the
+   * PREF_OTHER_DEFAULTS Map, specifying their full name.
+   *
+   * @param {string} pref
+   *        The name of the preference to set.
+   * @param {*} value The preference value.
+   */
+  set(pref, value) {
+    let { defaultValue, set } = this._getPrefDescriptor(pref);
+    if (typeof value != typeof defaultValue) {
+      throw new Error(`Invalid value type ${typeof value} for pref ${pref}`);
+    }
+    set(pref, value);
+  }
+
+  /**
+   * Clears the value for the preference with the given name.
+   *
+   * @param {string} pref
+   *        The name of the preference to clear.
+   */
+  clear(pref) {
+    let { clear } = this._getPrefDescriptor(pref);
+    clear(pref);
+  }
+
+  /**
+   * Builds the standard result groups.  See makeResultGroups.
+   *
+   * @param {object} options
+   *   See makeResultGroups.
+   * @returns {object}
+   *   The root group.
+   */
+  makeResultGroups(options) {
+    return makeResultGroups(options);
+  }
+
+  get resultGroups() {
+    if (!this.#resultGroups) {
+      this.#resultGroups = makeResultGroups({
+        showSearchSuggestionsFirst: this.get("showSearchSuggestionsFirst"),
+      });
+    }
+    return this.#resultGroups;
+  }
+
+  /**
+   * Sets the appropriate Firefox Suggest scenario based on the current Nimbus
+   * rollout (if any) and "hardcoded" rollouts (if any). The possible scenarios
+   * are:
+   *
+   * history
+   *   This is the scenario when the user is not in any rollouts. Firefox
+   *   Suggest suggestions are disabled.
+   * offline
+   *   This is the scenario for the "offline" rollout. Firefox Suggest
+   *   suggestions are enabled by default. Data collection is not enabled by
+   *   default, but the user can opt in in about:preferences. The onboarding
+   *   dialog is not shown.
+   * online
+   *   This is the scenario for the "online" rollout. Firefox Suggest
+   *   suggestions are enabled by default. Data collection is not enabled by
+   *   default, and the user will be shown an onboarding dialog that prompts
+   *   them to opt in to it. The user can also opt in in about:preferences.
+   *
+   * @param {string} [testOverrides]
+   *   This is intended for tests only. Pass to force the following:
+   *   `{ scenario, migrationVersion, defaultPrefs, isStartup }`
+   */
+  async updateFirefoxSuggestScenario(testOverrides = null) {
+    // Make sure we don't re-enter this method while updating prefs. Updates to
+    // prefs that are fallbacks for Nimbus variables trigger the pref observer
+    // in Nimbus, which triggers our Nimbus `onUpdate` callback, which calls
+    // this method again.
+    if (this._updatingFirefoxSuggestScenario) {
+      return;
+    }
+
+    let isStartup =
+      !this._updateFirefoxSuggestScenarioCalled || !!testOverrides?.isStartup;
+    this._updateFirefoxSuggestScenarioCalled = true;
+
+    try {
+      this._updatingFirefoxSuggestScenario = true;
+
+      // This is called early in startup by BrowserGlue, so make sure the user's
+      // region and our Nimbus variables are initialized since the scenario may
+      // depend on them. Also note that pref migrations may depend on the
+      // scenario, and since each migration is performed only once, at startup,
+      // prefs can end up wrong if their migrations use the wrong scenario.
+      await lazy.Region.init();
+      await lazy.NimbusFeatures.urlbar.ready();
+      this._clearNimbusCache();
+
+      // This also races TelemetryEnvironment's initialization, so wait for it
+      // to finish. TelemetryEnvironment is important because it records the
+      // values of a number of Suggest preferences. If we didn't wait, we could
+      // end up updating prefs after TelemetryEnvironment does its initial pref
+      // cache but before it adds its observer to be notified of pref changes.
+      // It would end up recording the wrong values on startup in that case.
+      if (!this._testSkipTelemetryEnvironmentInit) {
+        await lazy.TelemetryEnvironment.onInitialized();
+      }
+
+      this._updateFirefoxSuggestScenarioHelper(isStartup, testOverrides);
+    } finally {
+      this._updatingFirefoxSuggestScenario = false;
+    }
+
+    // Null check `_resolveFirefoxSuggestScenarioStartupPromise` since some
+    // tests force `isStartup` after actual startup and it's been set to null.
+    if (isStartup && this._resolveFirefoxSuggestScenarioStartupPromise) {
+      this._resolveFirefoxSuggestScenarioStartupPromise();
+      this._resolveFirefoxSuggestScenarioStartupPromise = null;
+    }
+  }
+
+  _updateFirefoxSuggestScenarioHelper(isStartup, testOverrides) {
+    // Updating the scenario is tricky and it's important to preserve the user's
+    // choices, so we describe the process in detail below. tl;dr:
+    //
+    // * Prefs exposed in the UI should be sticky.
+    // * Prefs that are both exposed in the UI and configurable via Nimbus
+    //   should be added to `uiPrefNamesByVariable` below.
+    // * Prefs that are both exposed in the UI and configurable via Nimbus don't
+    //   need to be specified as a `fallbackPref` in the feature manifest.
+    //   Access these prefs directly instead of through their Nimbus variables.
+    // * If you are modifying this method, keep in mind that setting a pref
+    //   that's a `fallbackPref` for a Nimbus variable will trigger the pref
+    //   observer inside Nimbus and call all `NimbusFeatures.urlbar.onUpdate`
+    //   callbacks. Inside this class we guard against that by using
+    //   `updatingFirefoxSuggestScenario`.
+    //
+    // The scenario-update process is described next.
+    //
+    // 1. Pick a scenario. If the user is in a Nimbus rollout, then Nimbus will
+    //    define it. Otherwise the user may be in a "hardcoded" rollout
+    //    depending on their region and locale. If the user is not in any
+    //    rollouts, then the scenario is "history", which means no Firefox
+    //    Suggest suggestions should appear.
+    //
+    // 2. Set prefs on the default branch appropriate for the scenario. We use
+    //    the default branch and not the user branch because conceptually each
+    //    scenario has a default behavior, which we want to distinguish from the
+    //    user's choices.
+    //
+    //    In particular it's important to consider prefs that are exposed in the
+    //    UI, like whether sponsored suggestions are enabled. Once the user
+    //    makes a choice to change a default, we want to preserve that choice
+    //    indefinitely regardless of the scenario the user is currently enrolled
+    //    in or future scenarios they might be enrolled in. User choices are of
+    //    course recorded on the user branch, so if we set scenario defaults on
+    //    the user branch too, we wouldn't be able to distinguish user choices
+    //    from default values. This is also why prefs that are exposed in the UI
+    //    should be sticky. Unlike non-sticky prefs, sticky prefs retain their
+    //    user-branch values even when those values are the same as the ones on
+    //    the default branch.
+    //
+    //    It's important to note that the defaults we set here do not persist
+    //    across app restarts. (This is a feature of the pref service; prefs set
+    //    programmatically on the default branch are not stored anywhere
+    //    permanent like firefox.js or user.js.) That's why BrowserGlue calls
+    //    `updateFirefoxSuggestScenario` on every startup.
+    //
+    // 3. Some prefs are both exposed in the UI and configurable via Nimbus,
+    //    like whether data collection is enabled. We absolutely want to
+    //    preserve the user's past choices for these prefs. But if the user
+    //    hasn't yet made a choice for a particular pref, then it should be
+    //    configurable.
+    //
+    //    For any such prefs that have values defined in Nimbus, we set their
+    //    default-branch values to their Nimbus values. (These defaults
+    //    therefore override any set in the previous step.) If a pref has a user
+    //    value, accessing the pref will return the user value; if it does not
+    //    have a user value, accessing it will return the value that was
+    //    specified in Nimbus.
+    //
+    //    This isn't strictly necessary. Since prefs exposed in the UI are
+    //    sticky, they will always preserve their user-branch values regardless
+    //    of their default-branch values, and as long as a pref is listed as a
+    //    `fallbackPref` for its corresponding Nimbus variable, Nimbus will use
+    //    the user-branch value. So we could instead specify fallback prefs in
+    //    Nimbus and always access values through Nimbus instead of through
+    //    prefs. But that would make preferences UI code a little harder to
+    //    write since the checked state of a checkbox would depend on something
+    //    other than its pref. Since we're already setting default-branch values
+    //    here as part of the previous step, it's not much more work to set
+    //    defaults for these prefs too, and it makes the UI code a little nicer.
+    //
+    // 4. Migrate prefs as necessary. This refers to any pref changes that are
+    //    neccesary across app versions: introducing and initializing new prefs,
+    //    removing prefs, or changing the meaning of existing prefs.
+
+    // 1. Pick a scenario
+    let scenario =
+      testOverrides?.scenario || this._getIntendedFirefoxSuggestScenario();
+
+    // 2. Set default-branch values for the scenario
+    let defaultPrefs =
+      testOverrides?.defaultPrefs || this.FIREFOX_SUGGEST_DEFAULT_PREFS;
+    let prefs = { ...defaultPrefs[scenario] };
+
+    // 3. Set default-branch values for prefs that are both exposed in the UI
+    // and configurable via Nimbus
+    for (let [variable, prefName] of Object.entries(
+      this.FIREFOX_SUGGEST_UI_PREFS_BY_VARIABLE
+    )) {
+      if (this._nimbus.hasOwnProperty(variable)) {
+        prefs[prefName] = this._nimbus[variable];
+      }
+    }
+
+    let defaults = Services.prefs.getDefaultBranch("browser.urlbar.");
+    for (let [name, value] of Object.entries(prefs)) {
+      // We assume all prefs are boolean right now.
+      defaults.setBoolPref(name, value);
+    }
+
+    // 4. Migrate prefs across app versions
+    if (isStartup) {
+      this._ensureFirefoxSuggestPrefsMigrated(scenario, testOverrides);
+    }
+
+    // Set the scenario pref only after migrating so that migrations can tell
+    // what the last-seen scenario was. Set it on the user branch so that its
+    // value persists across app restarts.
+    this.set("quicksuggest.scenario", scenario);
+  }
+
+  /**
+   * Returns the Firefox Suggest scenario the user should be enrolled in. This
+   * does *not* return the scenario they are currently enrolled in.
+   *
+   * @returns {string}
+   *   The scenario the user should be enrolled in.
+   */
+  _getIntendedFirefoxSuggestScenario() {
+    // If the user is in a Nimbus rollout, then Nimbus will define the scenario.
+    // Otherwise the user may be in a "hardcoded" rollout depending on their
+    // region and locale. If the user is not in any rollouts, then the scenario
+    // is "history", which means no Firefox Suggest suggestions will appear.
+    let scenario = this._nimbus.quickSuggestScenario;
+    if (!scenario) {
+      if (
+        lazy.Region.home == "US" &&
+        Services.locale.appLocaleAsBCP47.substring(0, 2) == "en"
+      ) {
+        // offline rollout for en locales in the US region
+        scenario = "offline";
+      } else {
+        // no rollout
+        scenario = "history";
+      }
+    }
+    if (!this.FIREFOX_SUGGEST_DEFAULT_PREFS.hasOwnProperty(scenario)) {
+      scenario = "history";
+      console.error(`Unrecognized Firefox Suggest scenario "${scenario}"`);
+    }
+    return scenario;
+  }
+
+  /**
+   * Prefs that are exposed in the UI and whose default-branch values are
+   * configurable via Nimbus variables. This getter returns an object that maps
+   * from variable names to pref names relative to `browser.urlbar`. See point 3
+   * in the comment inside `_updateFirefoxSuggestScenarioHelper()` for more.
+   *
+   * @returns {{ quickSuggestNonSponsoredEnabled: string; quickSuggestSponsoredEnabled: string; quickSuggestDataCollectionEnabled: string; }}
+   */
+  get FIREFOX_SUGGEST_UI_PREFS_BY_VARIABLE() {
+    return {
+      quickSuggestNonSponsoredEnabled: "suggest.quicksuggest.nonsponsored",
+      quickSuggestSponsoredEnabled: "suggest.quicksuggest.sponsored",
+      quickSuggestDataCollectionEnabled: "quicksuggest.dataCollection.enabled",
+    };
+  }
+
+  /**
+   * Default prefs relative to `browser.urlbar` per Firefox Suggest scenario.
+   *
+   * @returns {Record<Record<string, boolean>>}
+   */
+  get FIREFOX_SUGGEST_DEFAULT_PREFS() {
+    // Important notes when modifying this:
+    //
+    // If you add a pref to one scenario, you typically need to add it to all
+    // scenarios even if the pref is in firefox.js. That's because we need to
+    // allow for switching from one scenario to another at any time after
+    // startup. If we set a pref for one scenario on the default branch, we
+    // switch to a new scenario, and we don't set the pref for the new scenario,
+    // it will keep its default-branch value from the old scenario. The only
+    // possible exception is for prefs that make others unnecessary, like how
+    // when `quicksuggest.enabled` is false, none of the other prefs matter.
+    //
+    // Prefs not listed here for any scenario keep their values set in
+    // firefox.js.
+    return {
+      history: {
+        "quicksuggest.enabled": false,
+      },
+      offline: {
+        "quicksuggest.enabled": true,
+        "quicksuggest.dataCollection.enabled": false,
+        "quicksuggest.shouldShowOnboardingDialog": false,
+        "suggest.quicksuggest.nonsponsored": true,
+        "suggest.quicksuggest.sponsored": true,
+      },
+      online: {
+        "quicksuggest.enabled": true,
+        "quicksuggest.dataCollection.enabled": false,
+        "quicksuggest.shouldShowOnboardingDialog": true,
+        "suggest.quicksuggest.nonsponsored": true,
+        "suggest.quicksuggest.sponsored": true,
+      },
+    };
+  }
+
+  /**
+   * The current version of the Firefox Suggest prefs.
+   *
+   * @returns {number}
+   */
+  get FIREFOX_SUGGEST_MIGRATION_VERSION() {
+    return 2;
+  }
+
+  /**
+   * Migrates Firefox Suggest prefs to the current version if they haven't been
+   * migrated already.
+   *
+   * @param {string} scenario
+   *   The current Firefox Suggest scenario.
+   * @param {string} testOverrides
+   *   This is intended for tests only. Pass to force a migration version:
+   *   `{ migrationVersion }`
+   */
+  _ensureFirefoxSuggestPrefsMigrated(scenario, testOverrides) {
+    let currentVersion =
+      testOverrides?.migrationVersion !== undefined
+        ? testOverrides.migrationVersion
+        : this.FIREFOX_SUGGEST_MIGRATION_VERSION;
+    let lastSeenVersion = Math.max(
+      0,
+      this.get("quicksuggest.migrationVersion")
+    );
+    if (currentVersion <= lastSeenVersion) {
+      // Migration up to date.
+      return;
+    }
+
+    let version = lastSeenVersion;
+
+    // When the current scenario is online and the last-seen prefs version is
+    // unversioned, specially handle migration up to version 2.
+    if (!version && scenario == "online" && 2 <= currentVersion) {
+      this._migrateFirefoxSuggestPrefsUnversionedTo2Online();
+      version = 2;
+    }
+
+    // Migrate from the last-seen version up to the current version.
+    for (; version < currentVersion; version++) {
+      let nextVersion = version + 1;
+      let methodName = "_migrateFirefoxSuggestPrefsTo_" + nextVersion;
+      try {
+        this[methodName](scenario);
+      } catch (error) {
+        console.error(
+          `Error migrating Firefox Suggest prefs to version ${nextVersion}: ` +
+            error
+        );
+        break;
+      }
+    }
+
+    // Record the new last-seen migration version.
+    this.set("quicksuggest.migrationVersion", version);
+  }
+
+  /**
+   * Migrates unversioned Firefox Suggest prefs to version 2 but only when the
+   * user's current scenario is online. This case requires special handling that
+   * isn't covered by the usual migration path from unversioned to 2.
+   */
+  _migrateFirefoxSuggestPrefsUnversionedTo2Online() {
+    // Copy `suggest.quicksuggest` to `suggest.quicksuggest.nonsponsored` and
+    // clear the first.
+    let mainPref = "browser.urlbar.suggest.quicksuggest";
+    let mainPrefHasUserValue = Services.prefs.prefHasUserValue(mainPref);
+    if (mainPrefHasUserValue) {
+      this.set(
+        "suggest.quicksuggest.nonsponsored",
+        Services.prefs.getBoolPref(mainPref)
+      );
+      Services.prefs.clearUserPref(mainPref);
+    }
+
+    if (!this.get("quicksuggest.showedOnboardingDialog")) {
+      // The user was enrolled in history or offline, or they were enrolled in
+      // online and weren't shown the modal yet.
+      //
+      // If they were in history, they should now see suggestions by default,
+      // and we don't need to worry about any current pref values since Firefox
+      // Suggest is new to them.
+      //
+      // If they were in offline, they saw suggestions by default, but if they
+      // disabled the main suggestions pref, then both non-sponsored and
+      // sponsored suggestions were disabled and we need to carry that forward.
+      //
+      // If they were in online and weren't shown the modal yet, suggestions
+      // were disabled by default. The modal is shown only on startup, so it's
+      // possible they used Firefox for quite a while after being enrolled in
+      // online with suggestions disabled the whole time. If they looked at the
+      // prefs UI, they would have seen both suggestion checkboxes unchecked.
+      // For these users, ideally we wouldn't suddenly enable suggestions, but
+      // unfortunately there's no simple way to distinguish them from history
+      // and offline users at this point based on the unversioned prefs. We
+      // could check whether the user is or was enrolled in the initial online
+      // experiment; if they were, then disable suggestions. However, that's a
+      // little risky because it assumes future online rollouts will be
+      // delivered by new experiments and not by increasing the original
+      // experiment's population. If that assumption does not hold, we would end
+      // up disabling suggestions for all users who are newly enrolled in online
+      // even if they were previously in history or offline. Further, based on
+      // telemetry data at the time of writing, only a small number of users in
+      // online have not yet seen the modal. Therefore we will enable
+      // suggestions for these users too.
+      //
+      // Note that if the user is in online and hasn't been shown the modal yet,
+      // we'll show it at some point during startup right after this. However,
+      // starting with the version-2 prefs, the modal now opts the user in to
+      // only data collection, not suggestions as it previously did.
+
+      if (
+        mainPrefHasUserValue &&
+        !this.get("suggest.quicksuggest.nonsponsored")
+      ) {
+        // The user was in offline and disabled the main suggestions pref, so
+        // sponsored suggestions were automatically disabled too. We know they
+        // disabled the main pref since it has a false user-branch value.
+        this.set("suggest.quicksuggest.sponsored", false);
+      }
+      return;
+    }
+
+    // At this point, the user was in online, they were shown the modal, and the
+    // current scenario is online. In the unversioned prefs for online, the
+    // suggestion prefs were false on the default branch, but in the version-2
+    // prefs, they're true on the default branch.
+
+    if (mainPrefHasUserValue && this.get("suggest.quicksuggest.nonsponsored")) {
+      // The main pref is true on the user branch. The user opted in either via
+      // the modal or by checking the checkbox in the prefs UI. In the latter
+      // case, they were shown some informational text about data collection
+      // under the checkbox. Either way, they've opted in to data collection.
+      this.set("quicksuggest.dataCollection.enabled", true);
+      if (
+        !Services.prefs.prefHasUserValue(
+          "browser.urlbar.suggest.quicksuggest.sponsored"
+        )
+      ) {
+        // The sponsored pref does not have a user value, so the default-branch
+        // false value was the effective value and the user did not see
+        // sponsored suggestions. We need to override the version-2 default-
+        // branch true value by setting the pref to false.
+        this.set("suggest.quicksuggest.sponsored", false);
+      }
+    } else {
+      // The main pref is not true on the user branch, so the user either did
+      // not opt in or they later disabled suggestions in the prefs UI. Set the
+      // suggestion prefs to false on the user branch to override the version-2
+      // default-branch true values. The data collection pref is false on the
+      // default branch, but since the user was shown the modal, set it on the
+      // user branch too, where it's sticky, to record the user's choice not to
+      // opt in.
+      this.set("suggest.quicksuggest.nonsponsored", false);
+      this.set("suggest.quicksuggest.sponsored", false);
+      this.set("quicksuggest.dataCollection.enabled", false);
+    }
+  }
+
+  _migrateFirefoxSuggestPrefsTo_1(scenario) {
+    // Copy `suggest.quicksuggest` to `suggest.quicksuggest.nonsponsored` and
+    // clear the first.
+    let suggestQuicksuggest = "browser.urlbar.suggest.quicksuggest";
+    if (Services.prefs.prefHasUserValue(suggestQuicksuggest)) {
+      this.set(
+        "suggest.quicksuggest.nonsponsored",
+        Services.prefs.getBoolPref(suggestQuicksuggest)
+      );
+      Services.prefs.clearUserPref(suggestQuicksuggest);
+    }
+
+    // In the unversioned prefs, sponsored suggestions were shown only if the
+    // main suggestions pref `suggest.quicksuggest` was true, but now there are
+    // two independent prefs, so disable sponsored if the main pref was false.
+    if (!this.get("suggest.quicksuggest.nonsponsored")) {
+      switch (scenario) {
+        case "offline":
+          // Set the pref on the user branch. Suggestions are enabled by default
+          // for offline; we want to preserve the user's choice of opting out,
+          // and we want to preserve the default-branch true value.
+          this.set("suggest.quicksuggest.sponsored", false);
+          break;
+        case "online":
+          // If the user-branch value is true, clear it so the default-branch
+          // false value becomes the effective value.
+          if (this.get("suggest.quicksuggest.sponsored")) {
+            this.clear("suggest.quicksuggest.sponsored");
+          }
+          break;
+      }
+    }
+
+    // The data collection pref is new in this version. Enable it iff the
+    // scenario is online and the user opted in to suggestions. In offline, it
+    // should always start off false.
+    if (scenario == "online" && this.get("suggest.quicksuggest.nonsponsored")) {
+      this.set("quicksuggest.dataCollection.enabled", true);
+    }
+  }
+
+  _migrateFirefoxSuggestPrefsTo_2(scenario) {
+    // In previous versions of the prefs for online, suggestions were disabled
+    // by default; in version 2, they're enabled by default. For users who were
+    // already in online and did not enable suggestions (because they did not
+    // opt in, they did opt in but later disabled suggestions, or they were not
+    // shown the modal) we don't want to suddenly enable them, so if the prefs
+    // do not have user-branch values, set them to false.
+    if (this.get("quicksuggest.scenario") == "online") {
+      if (
+        !Services.prefs.prefHasUserValue(
+          "browser.urlbar.suggest.quicksuggest.nonsponsored"
+        )
+      ) {
+        this.set("suggest.quicksuggest.nonsponsored", false);
+      }
+      if (
+        !Services.prefs.prefHasUserValue(
+          "browser.urlbar.suggest.quicksuggest.sponsored"
+        )
+      ) {
+        this.set("suggest.quicksuggest.sponsored", false);
+      }
+    }
+  }
+
+  /**
+   * @returns {Promise}
+   *   This can be used to wait until the initial Firefox Suggest scenario has
+   *   been set on startup. It's resolved when the first call to
+   *   `updateFirefoxSuggestScenario()` finishes.
+   */
+  get firefoxSuggestScenarioStartupPromise() {
+    return this._firefoxSuggestScenarioStartupPromise;
+  }
+
+  /**
+   * @returns {boolean}
+   *   Whether the Firefox Suggest scenario is being updated. While true,
+   *   changes to related prefs should be ignored, depending on the observer.
+   *   Telemetry intended to capture user changes to the prefs should not be
+   *   recorded, for example.
+   */
+  get updatingFirefoxSuggestScenario() {
+    return this._updatingFirefoxSuggestScenario;
+  }
+
+  /**
+   * Adds a preference observer.  Observers are held weakly.
+   *
+   * @param {object} observer
+   *        An object that may optionally implement one or both methods:
+   *         - `onPrefChanged` invoked when one of the preferences listed here
+   *           change. It will be passed the pref name.  For prefs in the
+   *           `browser.urlbar.` branch, the name will be relative to the branch.
+   *           For other prefs, the name will be the full name.
+   *         - `onNimbusChanged` invoked when a Nimbus value changes. It will be
+   *           passed the name of the changed Nimbus variable.
+   */
+  addObserver(observer) {
+    this._observerWeakRefs.push(Cu.getWeakReference(observer));
+  }
+
+  /**
+   * Removes a preference observer.
+   *
+   * @param {object} observer
+   *   An observer previously added with `addObserver()`.
+   */
+  removeObserver(observer) {
+    for (let i = 0; i < this._observerWeakRefs.length; i++) {
+      let obs = this._observerWeakRefs[i].get();
+      if (obs && obs == observer) {
+        this._observerWeakRefs.splice(i, 1);
+        break;
+      }
+    }
+  }
+
+  /**
+   * Observes preference changes.
+   *
+   * @param {nsISupports} subject
+   *   The subject of the notification.
+   * @param {string} topic
+   *   The topic of the notification.
+   * @param {string} data
+   *   The data attached to the notification.
+   */
+  observe(subject, topic, data) {
+    let pref = data.replace(PREF_URLBAR_BRANCH, "");
+    if (!PREF_URLBAR_DEFAULTS.has(pref) && !PREF_OTHER_DEFAULTS.has(pref)) {
+      return;
+    }
+    this.#notifyObservers("onPrefChanged", pref);
+  }
+
+  /**
+   * Called when a pref tracked by UrlbarPrefs changes.
+   *
+   * @param {string} pref
+   *        The name of the pref, relative to `browser.urlbar.` if the pref is
+   *        in that branch.
+   */
+  onPrefChanged(pref) {
+    this._map.delete(pref);
+
+    // Some prefs may influence others.
+    switch (pref) {
+      case "autoFill.adaptiveHistory.useCountThreshold":
+        this._map.delete("autoFillAdaptiveHistoryUseCountThreshold");
+        return;
+      case "showSearchSuggestionsFirst":
+        this.#resultGroups = null;
+        return;
+    }
+
+    if (pref.startsWith("suggest.")) {
+      this._map.delete("defaultBehavior");
+    }
+
+    if (this.shouldHandOffToSearchModePrefs.includes(pref)) {
+      this._map.delete("shouldHandOffToSearchMode");
+    }
+  }
+
+  /**
+   * Called when the `NimbusFeatures.urlbar` value changes.
+   */
+  _onNimbusUpdate() {
+    let oldNimbus = this._clearNimbusCache();
+    let newNimbus = this._nimbus;
+
+    // Callback to observers having onNimbusChanged.
+    for (let name in newNimbus) {
+      if (oldNimbus[name] != newNimbus[name]) {
+        this.#notifyObservers("onNimbusChanged", name);
+      }
+    }
+
+    // If a change occurred to the Firefox Suggest scenario variable or any
+    // variables that correspond to prefs exposed in the UI, we need to update
+    // the scenario.
+    let variables = [
+      "quickSuggestScenario",
+      ...Object.keys(this.FIREFOX_SUGGEST_UI_PREFS_BY_VARIABLE),
+    ];
+    for (let name of variables) {
+      if (oldNimbus[name] != newNimbus[name]) {
+        this.updateFirefoxSuggestScenario();
+        return;
+      }
+    }
+
+    // If the current default-branch value of any pref is incorrect for the
+    // intended scenario, we need to update the scenario.
+    let scenario = this._getIntendedFirefoxSuggestScenario();
+    let intendedDefaultPrefs = this.FIREFOX_SUGGEST_DEFAULT_PREFS[scenario];
+    let defaults = Services.prefs.getDefaultBranch("browser.urlbar.");
+    for (let [name, value] of Object.entries(intendedDefaultPrefs)) {
+      // We assume all prefs are boolean right now.
+      if (defaults.getBoolPref(name) != value) {
+        this.updateFirefoxSuggestScenario();
+        return;
+      }
+    }
+  }
+
+  /**
+   * Clears cached Nimbus variables. The cache will be repopulated the next time
+   * `_nimbus` is accessed.
+   *
+   * @returns {object}
+   *   The value of the cache before it was cleared. It's an object that maps
+   *   from variable names to values.
+   */
+  _clearNimbusCache() {
+    let nimbus = this.__nimbus;
+    if (nimbus) {
+      for (let key of Object.keys(nimbus)) {
+        this._map.delete(key);
+      }
+      this.__nimbus = null;
+    }
+    return nimbus || {};
+  }
+
+  get _nimbus() {
+    if (!this.__nimbus) {
+      this.__nimbus = lazy.NimbusFeatures.urlbar.getAllVariables({
+        defaultValues: NIMBUS_DEFAULTS,
+      });
+    }
+    return this.__nimbus;
+  }
+
+  /**
+   * Returns the raw value of the given preference straight from Services.prefs.
+   *
+   * @param {string} pref
+   *        The name of the preference to get.
+   * @returns {*} The raw preference value.
+   */
+  _readPref(pref) {
+    let { defaultValue, get } = this._getPrefDescriptor(pref);
+    return get(pref, defaultValue);
+  }
+
+  /**
+   * Returns a validated and/or fixed-up value of the given preference.  The
+   * value may be validated for correctness, or it might be converted into a
+   * different value that is easier to work with than the actual value stored in
+   * the preferences branch.  Not all preferences require validation or fixup.
+   *
+   * The values returned from this method are the values that are made public by
+   * this module.
+   *
+   * @param {string} pref
+   *        The name of the preference to get.
+   * @returns {*} The validated and/or fixed-up preference value.
+   */
+  _getPrefValue(pref) {
+    switch (pref) {
+      case "defaultBehavior": {
+        let val = 0;
+        for (let type of Object.keys(SUGGEST_PREF_TO_BEHAVIOR)) {
+          let behavior = `BEHAVIOR_${SUGGEST_PREF_TO_BEHAVIOR[
+            type
+          ].toUpperCase()}`;
+          val |=
+            this.get("suggest." + type) && Ci.mozIPlacesAutoComplete[behavior];
+        }
+        return val;
+      }
+      case "shouldHandOffToSearchMode":
+        return this.shouldHandOffToSearchModePrefs.some(
+          prefName => !this.get(prefName)
+        );
+      case "autoFillAdaptiveHistoryUseCountThreshold":
+        const nimbusValue =
+          this._nimbus.autoFillAdaptiveHistoryUseCountThreshold;
+        return nimbusValue === undefined
+          ? this.get("autoFill.adaptiveHistory.useCountThreshold")
+          : parseFloat(nimbusValue);
+    }
+    return this._readPref(pref);
+  }
+
+  /**
+   * Returns a descriptor of the given preference.
+   *
+   * @param {string} pref The preference to examine.
+   * @returns {object} An object describing the pref with the following shape:
+   *          { defaultValue, get, set, clear }
+   */
+  _getPrefDescriptor(pref) {
+    let branch = Services.prefs.getBranch(PREF_URLBAR_BRANCH);
+    let defaultValue = PREF_URLBAR_DEFAULTS.get(pref);
+    if (defaultValue === undefined) {
+      branch = Services.prefs;
+      defaultValue = PREF_OTHER_DEFAULTS.get(pref);
+      if (defaultValue === undefined) {
+        let nimbus = this._getNimbusDescriptor(pref);
+        if (nimbus) {
+          return nimbus;
+        }
+        throw new Error("Trying to access an unknown pref " + pref);
+      }
+    }
+
+    let type;
+    if (!Array.isArray(defaultValue)) {
+      type = PREF_TYPES.get(typeof defaultValue);
+    } else {
+      if (defaultValue.length != 2) {
+        throw new Error("Malformed pref def: " + pref);
+      }
+      [defaultValue, type] = defaultValue;
+      type = PREF_TYPES.get(type);
+    }
+    if (!type) {
+      throw new Error("Unknown pref type: " + pref);
+    }
+    return {
+      defaultValue,
+      get: branch[`get${type}Pref`],
+      // Float prefs are stored as Char.
+      set: branch[`set${type == "Float" ? "Char" : type}Pref`],
+      clear: branch.clearUserPref,
+    };
+  }
+
+  /**
+   * Returns a descriptor for the given Nimbus property, if it exists.
+   *
+   * @param {string} name
+   *   The name of the desired property in the object returned from
+   *   NimbusFeatures.urlbar.getAllVariables().
+   * @returns {object}
+   *   An object describing the property's value with the following shape (same
+   *   as _getPrefDescriptor()):
+   *     { defaultValue, get, set, clear }
+   *   If the property doesn't exist, null is returned.
+   */
+  _getNimbusDescriptor(name) {
+    if (!this._nimbus.hasOwnProperty(name)) {
+      return null;
+    }
+    return {
+      defaultValue: this._nimbus[name],
+      get: () => this._nimbus[name],
+      set() {
+        throw new Error(`'${name}' is a Nimbus value and cannot be set`);
+      },
+      clear() {
+        throw new Error(`'${name}' is a Nimbus value and cannot be cleared`);
+      },
+    };
+  }
+
+  /**
+   * Initializes the showSearchSuggestionsFirst pref based on the matchGroups
+   * pref.  This function can be removed when the corresponding UI migration in
+   * BrowserGlue.sys.mjs is no longer needed.
+   */
+  initializeShowSearchSuggestionsFirstPref() {
+    let matchGroups = [];
+    let pref = Services.prefs.getCharPref("browser.urlbar.matchGroups", "");
+    try {
+      matchGroups = pref.split(",").map(v => {
+        let group = v.split(":");
+        return [group[0].trim().toLowerCase(), Number(group[1])];
+      });
+    } catch (ex) {}
+    let groupNames = matchGroups.map(group => group[0]);
+    let suggestionIndex = groupNames.indexOf("suggestion");
+    let generalIndex = groupNames.indexOf("general");
+    let showSearchSuggestionsFirst =
+      generalIndex < 0 ||
+      (suggestionIndex >= 0 && suggestionIndex < generalIndex);
+    let oldValue = Services.prefs.getBoolPref(
+      "browser.urlbar.showSearchSuggestionsFirst"
+    );
+    Services.prefs.setBoolPref(
+      "browser.urlbar.showSearchSuggestionsFirst",
+      showSearchSuggestionsFirst
+    );
+
+    // Pref observers aren't called when a pref is set to its current value, but
+    // we always want to set matchGroups to the appropriate default value via
+    // onPrefChanged, so call it now if necessary.  This is really only
+    // necessary for tests since the only time this function is called outside
+    // of tests is by a UI migration in BrowserGlue.
+    if (oldValue == showSearchSuggestionsFirst) {
+      this.onPrefChanged("showSearchSuggestionsFirst");
+    }
+  }
+
+  /**
+   * Return whether or not persisted search terms is enabled.
+   *
+   * @returns {boolean} true: if enabled.
+   */
+  isPersistedSearchTermsEnabled() {
+    return (
+      this.get("showSearchTermsFeatureGate") &&
+      this.get("showSearchTerms.enabled") &&
+      !this.get("browser.search.widget.inNavBar")
+    );
+  }
+
+  #notifyObservers(method, changed) {
+    for (let i = 0; i < this._observerWeakRefs.length; ) {
+      let observer = this._observerWeakRefs[i].get();
+      if (!observer) {
+        // The observer has been GC'ed, so remove it from our list.
+        this._observerWeakRefs.splice(i, 1);
+        continue;
+      }
+      if (method in observer) {
+        try {
+          observer[method](changed);
+        } catch (ex) {
+          console.error(ex);
+        }
+      }
+      ++i;
+    }
+  }
+
+  #resultGroups = null;
+}
+
+export var UrlbarPrefs = new Preferences();