Examine source code of Video Commander

{
  "name": "Video Commander",
  "short_name": "videocommander",
  "version": "0.5",
  "manifest_version": 2,
  "description": "Video Commander provides keyboard shortcuts to loop, speed up, speed down, rewind time, advance time and other handy actions",
  "homepage_url": "https://github.com/noraworld/videocommander",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "options_ui": {
    "page": "options.html"
  },
  "browser_action": {
    "default_icon": "icons/icon128.png"
  },
  "content_scripts": [
    {
      "all_frames": true,
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "script.css"
      ],
      "js": [
        "jquery.js",
        "script.js"
      ]
    }
  ],
  "applications": {
    "gecko": {
      "id": "videocommander@noraworld.com",
      "strict_min_version": "57.0"
    }
  }
}