Examine source code of Halloween Memory

{
  "manifest_version": 2,
  "name": "Halloween Memory",
  "version": "1.0",
  "description": "Halloween Memory is a Memory fun. Match all the identical cards before time runs out",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": {
      "48": "images/halloween-logo.png"
    },
    "default_title": "Open Game Popup",
    "default_popup": "popup.html"
  },
  "icons": {
    "48": "images/halloween-logo.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{2f2722e3-448f-449c-a34c-e034b19145e3}"
    }
  }
}