Examine source code of SteamProfilePreviewer

{
  "manifest_version": 2,
  "name": "SteamProfilePreviewer",
  "version": "2.4.0",
  "description": "Adds a preview button to the items on the Steam points shop to showcase them on YOUR profile.",
  "icons": {},
  "permissions": [
    "storage",
    "https://steamcommunity.com/profiles/*",
    "https://steamcommunity.com/id/*",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.steampowered.com/points/shop*"
      ],
      "js": [
        "shop.js",
        "menu/menu.js"
      ]
    },
    {
      "matches": [
        "https://steamcommunity.com/*previewprofile*"
      ],
      "js": [
        "gameProfile-iframe.js"
      ],
      "all_frames": true
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{4d24feab-f58e-4ab7-acd5-b79ae16473f3}",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}