Examine source code of Simple Character Counter

{
  "manifest_version": 3,
  "name": "Character Counter",
  "version": "1.1",
  "description": "Displays the character count of the selected text.",
  "author": "Semih Çelikol",
  "homepage_url": "https://semihcelikol.com",
  "developer": {
    "name": "Semih Çelikol",
    "url": "https://semihcelikol.com/"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "semihcelikol@character-counter"
    }
  },
  "permissions": [
    "contextMenus"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "icons": {
    "48": "icons/icon48.png",
    "64": "icons/icon64.png",
    "96": "icons/icon96.png"
  }
}