Examine source code of TMSync

{
  "manifest_version": 2,
  "name": "TMSync",
  "description": "Automatically track what you watch and keep your trackers up to date.",
  "version": "1.10.2",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "128": "icon/128.png"
  },
  "homepage_url": "https://github.com/kasusoba/TMSync",
  "permissions": [
    "storage",
    "alarms",
    "scripting",
    "identity",
    "activeTab",
    "https://api.trakt.tv/*",
    "https://anilist.co/*",
    "https://graphql.anilist.co/*",
    "https://raw.githubusercontent.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "tmsync@onesal.me",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "TMSync",
    "default_popup": "popup.html"
  },
  "options_ui": {
    "open_in_tab": true,
    "page": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://anilist.co/*",
        "*://www.anilist.co/*"
      ],
      "js": [
        "content-scripts/anilist.js"
      ]
    },
    {
      "matches": [
        "*://app.trakt.tv/*",
        "*://trakt.tv/*",
        "*://www.trakt.tv/*"
      ],
      "js": [
        "content-scripts/trakt.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "content-scripts/anilist.css",
    "content-scripts/content.css",
    "content-scripts/picker.css",
    "content-scripts/trakt.css"
  ],
  "optional_permissions": [
    "*://*/*"
  ]
}