Examine source code of Pixiv Pass

{
  "manifest_version": 2,
  "name": "Pixiv Pass-dev",
  "description": "Preview Pixiv artwork with its ID and provide download link",
  "version": "0.2.1",
  "icons": {
    "48": "icons/PP-48.png"
  },
  "permissions": [
    "downloads",
    "clipboardRead",
    "storage",
    "webRequest",
    "*://*.pixiv.net/*"
  ],
  "browser_action": {
    "default_popup": "index.html",
    "default_icon": "icons/PP-32.png",
    "default_title": "Pixiv Pass"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{89da8984-4948-4922-8b83-886546bce1a9}"
    }
  }
}