Examine source code of Señalador button

{
  "applications": {
    "gecko": {
      "id": "senalador_btn@senalador.es",
      "strict_min_version": "59.0"
    }
  },
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "version": "2.3.2resigned1",
  "default_locale": "en",
  "description": "__MSG_extensionDescription__",
  "homepage_url": "https://senalador.es",
  "icons": {
    "48": "icons/treasureChest_48.png",
    "96": "icons/treasureChest_96.png",
    "128": "icons/treasureChest_128.png",
    "256": "icons/treasureChest_256.png",
    "512": "icons/treasureChest.png"
  },
  "permissions": [
    "notifications",
    "storage",
    "tabs",
    "<all_urls>"
  ],
  "browser_action": {
    "browser_style": true,
    "default_icon": "icons/treasureChest.png",
    "default_title": "__MSG_openDashboard__"
  },
  "page_action": {
    "browser_style": true,
    "default_icon": "icons/treasureChest.png",
    "default_title": "__MSG_saveInSenalador__"
  },
  "background": {
    "scripts": [
      "background/index.js",
      "background/saveBookmark.js",
      "background/openDashboard.js"
    ]
  },
  "options_ui": {
    "browser_style": true,
    "page": "options/options.html"
  }
}