Examine source code of Discogs TV

{
  "manifest_version": 2,
  "name": "Discogs TV",
  "version": "0.3.1",
  "description": "Adds a feed of random videos to Discogs label and artist pages.",
  "icons": {
    "128": "assets/icon-128.png",
    "256": "assets/icon-256.png",
    "512": "assets/icon-512.png"
  },
  "permissions": [
    "activeTab",
    "storage",
    "*://*.discogs.com/*",
    "https://api.discogs.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.discogs.com/label/*",
        "*://*.discogs.com/artist/*"
      ],
      "js": [
        "browser-polyfill.js",
        "content_script.js"
      ],
      "css": [
        "style.css"
      ]
    }
  ],
  "background": {
    "scripts": [
      "browser-polyfill.js",
      "background_script.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "discogs-label-explore@extension.local"
    }
  }
}