Examine source code of Fertilizer Calculator

{
  "manifest_version": 2,
  "name": "Fertilizer Calculator",
  "version": "1.0",
  "description": "Easily calculate the amount of fertilizer needed for various crops.",
  "permissions": [],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "128": "images/fert-logo.png"
    }
  },
  "icons": {
    "128": "images/fert-logo.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{8aacf4fd-f0e8-4dea-8ae6-a713304bf886}"
    }
  }
}