Examine source code of Image Grabber

{
  "manifest_version": 2,
  "name": "Image Grabber",
  "version": "1.0",
  "description": "A user-friendly and powerful image downloader that allows you to easily download all images from your current webpage.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "popup.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a118cb21-d547-4202-a91e-4679e118ec59}"
    }
  }
}