Examine source code of Game Assistant

{
  "name": "Game Assistant",
  "description": "__MSG_extDescription__",
  "version": "1.2.1",
  "default_locale": "en",
  "manifest_version": 2,
  "icons": {
    "16": "images/icons/16.png",
    "48": "images/icons/48.png",
    "128": "images/icons/128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.steampowered.com/*",
        "*://steampowered.com/*",
        "*://steambuy.com/*",
        "*://*.steampay.com/*",
        "*://*.epicgames.com/*",
        "*://epicgames.com/*",
        "*://*.gog.com/*",
        "*://gog.com/*"
      ],
      "js": [
        "index.content.js"
      ]
    }
  ],
  "permissions": [
    "notifications",
    "storage",
    "tabs",
    "https://*.opera-api.com/",
    "https://*.igdb.com/",
    "https://*.steammachine.ru/*",
    "*://*.steampowered.com/*",
    "*://steampowered.com/*",
    "*://steambuy.com/*",
    "*://*.steampay.com/*",
    "*://*.epicgames.com/*",
    "*://epicgames.com/*",
    "*://*.gog.com/*",
    "*://gog.com/*"
  ],
  "browser_action": {
    "default_icon": {
      "16": "images/icons/16.png",
      "24": "images/icons/24.png",
      "32": "images/icons/32.png"
    },
    "default_popup": "popup.html"
  }
}