Examine source code of voz Emoticons

{
  "manifest_version": 2,
  "name": "voz Emoticons",
  "version": "1.1a",
  "author": "Vinh Pham",
  "description": "Adding Voz Emoticons",
  "icons": {
    "56": "icons/pepe-icon.png"
  },
  "permissions": [
    "activeTab",
    "tabs",
    "*://forums.voz.vn/*"
  ],
  "web_accessible_resources": [
    "icons/*.png",
    "icons/*.gif",
    "icons/*.jpg"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://forums.voz.vn/*"
      ],
      "js": [
        "test.js"
      ],
      "css": [
        "inject_style.css"
      ]
    }
  ]
}