count of
    // how many about:tabcrashed pages exist, so that they
    // can decide whether or not to display the "Restore All
    // Crashed Tabs" button.
    let count = gAboutTabCrashedPages.size;

    for (let actor of gAboutTabCrashedPages.keys()) {
      let browser = actor.browsingContext.top.embedderElement;
      if (browser) {
        browser.sendMessageToActor("UpdateCount", { count }, "AboutTabCrashed");
      }
    }
  }
}
PK