Examine source code of HealthGuard

{
  "applications": {
    "gecko": {
      "id": "firefox@hg.newsguardtech.com"
    }
  },
  "short_name": "HealthGuard",
  "author": "NewsGuard",
  "name": "HealthGuard",
  "description": "HealthGuard's ratings help users know which health news and medical information websites to trust.",
  "manifest_version": 2,
  "browser_action": {
    "default_popup": "index.html",
    "default_title": "HealthGuard"
  },
  "version": "4.3.0",
  "icons": {
    "16": "./assets/icons/png/NewsGuard_Shield_16.png",
    "48": "./assets/icons/png/NewsGuard_Shield_48.png",
    "128": "./assets/icons/png/NewsGuard_Shield_128.png"
  },
  "permissions": [
    "tabs",
    "storage",
    "https://*/"
  ],
  "background": {
    "scripts": [
      "static/js/background.bundle.healthguard.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "static/js/content.bundle.healthguard.js"
      ]
    }
  ]
}