Examine source code of Tab Refresh

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "description": "__MSG_extensionDescription__",
  "version": "1.4.8",
  "homepage_url": "https://github.com/jhonatasrm/tab-refresh",
  "default_locale": "en",
  "author": "Jhonatas Machado",
  "applications": {
    "gecko": {
      "id": "refresh-tab@jhonatasrm.com",
      "strict_min_version": "57.0"
    }
  },
  "background": {
    "scripts": [
      "/js/background.js"
    ]
  },
  "icons": {
    "40": "res/icons/icon.png",
    "80": "res/icons/icon@2x.png"
  },
  "browser_action": {
    "default_icon": "res/icons/refresh_tab_32.png",
    "default_title": "__MSG_message_timer_min__"
  },
  "options_ui": {
    "browser_style": false,
    "open_in_tab": true,
    "page": "html/preferences.html"
  },
  "permissions": [
    "tabs",
    "storage",
    "menus",
    "contextMenus"
  ]
}