Examine source code of 4chanMediaDownloader

{
  "manifest_version": 2,
  "name": "4chanMediaDownloader",
  "description": "Add a download button for each media in a thread. Can bulk download all media at once.",
  "version": "1.0.8",
  "browser_specific_settings": {
    "gecko": {
      "id": "{e5208388-1e55-49fb-91cf-f8b79c128f56}",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "64": "icons/icon.png",
    "128": "icons/icon-128x128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://boards.4chan.org/*",
        "*://boards.4channel.org/*",
        "*://localhost/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "permissions": [
    "downloads",
    "downloads.open"
  ],
  "content_security_policy": "default-src 'self'"
}