Examine source code of Football Scores Basic

{
  "manifest_version": 2,
  "name": "Football Scores Basic",
  "version": "1.0",
  "description": "This utility helps users to track sports match results, specifically football match results.",
  "permissions": [],
  "browser_action": {
    "default_popup": "game.html",
    "default_icon": {
      "128": "images/foot-logo.png"
    }
  },
  "icons": {
    "128": "images/foot-logo.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{716e2217-47ed-4f08-9adf-0831be34af98}"
    }
  }
}