Examine source code of Chess Notifier

{
  "name": "Chess Notifier",
  "description": "Get Chess.com browser notifications on your desktop.",
  "version": "0.2.3resigned1",
  "manifest_version": 2,
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "*://api.chess.com/*",
    "tabs",
    "storage",
    "notifications"
  ],
  "icons": {
    "64": "icons/128/pawn_color.png"
  },
  "options_ui": {
    "page": "options.html"
  },
  "developer": {
    "name": "Saša Stamenković",
    "url": "http://umpirsky.com"
  },
  "applications": {
    "gecko": {
      "id": "chess-notifier@umpirsky.com"
    }
  },
  "browser_action": {
    "default_icon": "icons/64/pawn.svg",
    "theme_icons": [
      {
        "light": "icons/64/pawn_light.svg",
        "dark": "icons/64/pawn.svg",
        "size": 16
      },
      {
        "light": "icons/64/pawn_light.svg",
        "dark": "icons/64/pawn.svg",
        "size": 32
      }
    ]
  }
}