Examine source code of BuyForMee

{
  "manifest_version": 2,
  "name": "BuyForMee",
  "description": "Capture url link from website",
  "version": "1.0",
  "browser_action": {
    "default_icon": "icon128.png",
    "default_title": "Add to BuyForMee\nClick to capture product url"
  },
  "permissions": [
    "tabs",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "icons": {
    "16": "icon16.png",
    "32": "icon32.png",
    "48": "icon48.png",
    "128": "icon128.png"
  }
}