Examine source code of Character Counter Tool

{
  "manifest_version": 2,
  "name": "Character Counter Tool",
  "version": "1.0",
  "description": "Quickly count characters and words in your text.",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_popup": "popup.html",
    "default_title": "Character Counter"
  },
  "permissions": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{e6b3e042-f881-46f8-9937-24398b1cd3e4}"
    }
  }
}