Examine source code of Play Tetris

{
  "name": "Play Tetris",
  "description": "Play tetris",
  "author": "Faruk Cepni",
  "version": "1.0.0",
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{89470e07-b0ab-4e8e-ad0f-fdf18193e2a5}"
    }
  },
  "browser_action": {
    "default_popup": "main.html"
  },
  "icons": {
    "16": "tetris-16.png",
    "24": "tetris-24.png",
    "32": "tetris-32.png",
    "64": "tetris-64.png",
    "128": "tetris-128.png",
    "256": "tetris-256.png",
    "512": "tetris-512.png"
  }
}