Examine source code of Character Counter

{
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "description": "Count the amount of characters, words, sentences and more by selecting text and right-clicking.",
  "icons": {
    "16": "icon-16.png",
    "64": "icon-64.png",
    "128": "icon-128.png"
  },
  "manifest_version": 2,
  "name": "Character Counter",
  "permissions": [
    "contextMenus"
  ],
  "version": "1.0.4",
  "default_locale": "en"
}