Examine source code of Things To Get Me

{
  "name": "Things To Get Me",
  "version": "4.5",
  "description": "The universal wish-list maker. Add items to your gift list from any website.",
  "permissions": [
    "storage",
    "tabs",
    "activeTab",
    "clipboardWrite",
    "*://*.thingstogetme.com/*"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/icon-16.png",
      "32": "images/icon-32.png",
      "48": "images/icon-48.png",
      "128": "images/icon-128.png"
    }
  },
  "icons": {
    "16": "images/icon-16.png",
    "32": "images/icon-32.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "applications": {
    "gecko": {
      "id": "firefox@thingstogetme.com"
    }
  },
  "manifest_version": 2
}