Examine source code of Auto Fullscreen

{
  "description": "Auto Fullscreen for Firefox Quantum",
  "manifest_version": 2,
  "name": "AutoFullscreen",
  "version": "1.0.0.3resigned1",
  "homepage_url": "https://github.com/tazeat/AutoFullscreen",
  "background": {
    "scripts": [
      "startup.js"
    ]
  },
  "icons": {
    "48": "icons/fullscreen_black_48x48.png",
    "96": "icons/fullscreen_black_96x96.png"
  },
  "applications": {
    "gecko": {
      "strict_min_version": "48.0",
      "id": "{d320c473-63c2-47ab-87f8-693b1badb5e3}"
    }
  }
}