Examine source code of Word Count Premium

{
  "background": {
    "scripts": [
      "content.js"
    ]
  },
  "browser_action": {
    "default_icon": "wc.png",
    "default_popup": "warning.html",
    "default_title": "Word Counter"
  },
  "description": "Instruction to Use: Just highlight or select the text/Words, right click, and click the Word Counter icon!",
  "icons": {
    "16": "wc.png",
    "48": "wordCount.png",
    "96": "wordCount.png"
  },
  "key": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvo/wwbxs5zUZTYjA+lZXPPDq74d60pGHn+LyNwsJYkHe8LfhuATqRO6MpwOQy2c2zSV6T7Pu0NAlX3ioMFO9j5a1Y+ThcydeWRTEtkogOpB3ULXuAsgHTAaatW/DjXSgxny4a8jVh5A8b2f0fi2+arxBYvo8PD1yw+xOMIfLOGUi5jAWwqUx1tfX4bwAf2+TNwbks7+agN/60ugkjzBNMNLFdf8nuZ4hXJTGxqMIFooMJRtarp3ELZ6+yNHamb1Ve4Dzi2EdDqZXj6oGR4RN/Jb0KgF2QxJqWgdyIcxakiGoWxvV335UJCNDIt6svwcTb5LSHdCastrmVKj74oLqPwIDAQAB",
  "manifest_version": 2,
  "name": "Word Counter Premium",
  "permissions": [
    "contextMenus",
    "tabs",
    "http://*/*",
    "https://*/*",
    "https://docs.google.com/"
  ],
  "short_name": "Count words and characters on a page",
  "update_url": "https://clients2.google.com/service/update2/crx",
  "version": "1.0"
}