Examine source code of Did it Tera?

{
  "manifest_version": 3,
  "name": "Did it Tera?",
  "version": "0.1.1",
  "description": "Adds an info text under the opponent's team with the name and type of the terastallized Pokémon.",
  "icons": {
    "16": "images/icon-16.png",
    "32": "images/icon-32.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://play.pokemonshowdown.com/*",
        "*://*.psim.us/*"
      ],
      "js": [
        "scripts/content.js"
      ]
    }
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "app@didit.tera"
    }
  }
}