Examine source code of Simple Tally Counter

{
  "manifest_version": 2,
  "name": "Simple Tally Counter",
  "version": "1.0",
  "description": "A simple tally counter Firefox extension.",
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{7521d61e-5e2b-4569-ba4e-887576d7958d}"
    }
  }
}