Examine source code of tab-invaders

{
  "manifest_version": 2,
  "icons": {
    "16": "5abf8a59f40e30e5015b6d7c8e0c420c.png",
    "48": "66281947e2c9299e7596e31b60aa157a.png",
    "128": "7b0c95e3a016372139c349ebd009be40.png"
  },
  "permissions": [
    "tabs",
    "storage",
    "activeTab",
    "<all_urls>"
  ],
  "browser_action": {
    "default_icon": {
      "16": "5abf8a59f40e30e5015b6d7c8e0c420c.png",
      "48": "66281947e2c9299e7596e31b60aa157a.png",
      "128": "7b0c95e3a016372139c349ebd009be40.png"
    },
    "default_title": "Tab Invaders"
  },
  "background": {
    "scripts": [
      "button.js"
    ],
    "persistent": false
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "applications": {
    "gecko": {
      "id": "{902ec4bc-446a-4485-b979-a6a749ff94c8}",
      "strict_min_version": "60.0"
    }
  },
  "name": "tab-invaders",
  "author": "Matthew Knox",
  "version": "1.1.0",
  "description": "A game of space invaders to deal with your browser tabs",
  "homepage_url": "https://github.com/mrkno/tab-invaders"
}