Examine source code of Cashback Monitor

{
  "icons": {
    "16": "icon16.plasmo.e7bcd3ac.png",
    "32": "icon32.plasmo.ce39377b.png",
    "48": "icon48.plasmo.3c17e113.png",
    "64": "icon64.plasmo.df317abe.png",
    "128": "icon128.plasmo.6a4310c5.png"
  },
  "manifest_version": 2,
  "browser_action": {
    "default_icon": {
      "16": "icon16.plasmo.e7bcd3ac.png",
      "32": "icon32.plasmo.ce39377b.png",
      "48": "icon48.plasmo.3c17e113.png",
      "64": "icon64.plasmo.df317abe.png",
      "128": "icon128.plasmo.6a4310c5.png"
    },
    "default_popup": "popup.html"
  },
  "version": "0.1.2",
  "author": "CashbackAnt",
  "name": "Cashback Monitor",
  "description": "Help online shoppers find the best cashback rates available.",
  "homepage_url": "https://www.cashbackant.com",
  "background": {
    "scripts": [
      "static/background/index.js"
    ]
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "permissions": [
    "storage",
    "tabs",
    "activeTab",
    "https://www.cashbackant.com/*",
    "https://cashbackant.com/*",
    "http://127.0.0.1:8888/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.cashbackant.com/*",
        "http://127.0.0.1:8888/*"
      ],
      "js": [
        "cashbackant.8da36d51.js"
      ],
      "css": []
    }
  ],
  "default_locale": "en",
  "browser_specific_settings": {
    "gecko": {
      "id": "{6d788d20-cc52-452d-aa25-773999baf9a9}"
    }
  }
}