MB 419: Mullvad Browser migration procedures.

    // Base Browser-specific version of _migrateUI.

    this._migrateUIBB();

    // Mullvad Browser-specific version of _migrateUI.

    this._migrateUIMB();

    if (!Services.prefs.prefHasUserValue(PREF_PDFJS_ISDEFAULT_CACHE_STATE)) {

      lazy.PdfJs.checkIsDefault(this._isNewProfile);

    }

    Services.prefs.setIntPref(MIGRATION_PREF, MIGRATION_VERSION);

  },

  // Use this method for any MB migration that can be run just before showing

  // the UI.

  // Anything that critically needs to be migrated earlier should not use this.

  _migrateUIMB() {

    // Version 1: Mullvad Browser 14.5a6: Clear home page update url preference

    //            (mullvad-browser#411).

    const MB_MIGRATION_VERSION = 1;

    const MIGRATION_PREF = "mullvadbrowser.migration.version";

    // If we decide to force updating users to pass through any version

    // following 14.5, we can remove this check, and check only whether

    // MIGRATION_PREF has a user value, like Mozilla does.

    if (this._isNewProfile) {

      // Do not migrate fresh profiles

      Services.prefs.setIntPref(MIGRATION_PREF, MB_MIGRATION_VERSION);

      return;

    } else if (this._isNewProfile === undefined) {

      // If this happens, check if upstream updated their function and do not

      // set this member anymore!

      console.error("_migrateUIMB: this._isNewProfile is undefined.");

    }

    const currentVersion = Services.prefs.getIntPref(MIGRATION_PREF, 0);

    if (currentVersion < 1) {

      Services.prefs.clearUserPref("mullvadbrowser.post_update.url");

    }

    Services.prefs.setIntPref(MIGRATION_PREF, MB_MIGRATION_VERSION);

  },

  async _showUpgradeDialog() {

    const data = await lazy.OnboardingMessageProvider.getUpgradeMessage();

    const { gBrowser } = lazy.BrowserWindowTracker.getTopWindow();