Examine source code of Word Counter

{
  "name": "Word Counter",
  "version": "1.0.1",
  "description": "Instantly count words, characters and characters without white spaces by typing or copy-pasting your text in our free extension word count tool.",
  "manifest_version": 2,
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "word-count.js"
      ]
    }
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Word Counter"
  }
}