Examine source code of GoBird

{
  "name": "Gobird",
  "version": "1",
  "description": "Supporting Go links off vpn",
  "manifest_version": 2,
  "icons": {
    "16": "images/twitter16.png",
    "32": "images/twitter32.png",
    "48": "images/twitter48.png",
    "128": "images/twitter128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "16": "images/twitter16.png",
      "32": "images/twitter32.png",
      "48": "images/twitter48.png",
      "128": "images/twitter128.png"
    }
  },
  "permissions": [
    "tabs",
    "webRequest",
    "webNavigation",
    "webRequestBlocking",
    "http://*/",
    "https://*/"
  ]
}