Examine source code of Background Tab Timer

{
  "manifest_version": 2,
  "name": "Background Tab Timer",
  "version": "1.0",
  "description": "Automatically close background tabs after a specified time.",
  "permissions": [
    "tabs",
    "background"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "anh": {
    "48": "anh.png"
  },
  "browser_action": {
    "default_title": "Background Tab Timer"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5f1d0875-5c50-45c4-9808-ce276d2f8a16}"
    }
  }
}