Examine source code of Screen Saver Keeper

{
  "version": "0.1.3",
  "manifest_version": 2,
  "offline_enabled": true,
  "short_name": "keep-awake",
  "name": "Screen Saver Keeper",
  "background": {
    "page": "lib/chrome/background.html"
  },
  "homepage_url": "https://mybrowseraddon.com/keep-awake.html",
  "permissions": [
    "power",
    "storage",
    "contextMenus",
    "notifications"
  ],
  "description": "With a single click of the extension's icon on the Firefox toolbar, you can prevent your computer screen from automatically turning off or switch to energy-saving screen mode.",
  "browser_action": {
    "default_title": "Keep Awake (Display | System)",
    "default_icon": {
      "16": "data/icons/16.png",
      "32": "data/icons/32.png",
      "48": "data/icons/48.png",
      "64": "data/icons/64.png"
    }
  },
  "icons": {
    "16": "data/icons/16.png",
    "32": "data/icons/32.png",
    "48": "data/icons/48.png",
    "64": "data/icons/64.png",
    "128": "data/icons/128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4ea7ea1d-0fac-453d-abe5-de141fd59447}"
    }
  }
}