Examine source code of PowerWriting

{
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "powerwritingai@extension.com",
      "strict_min_version": "42.0"
    }
  },
  "name": "PowerWriting",
  "description": "Improve your writing skills in multiple languages with this extension.",
  "version": "0.0.1",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    },
    "default_popup": "options.html"
  },
  "background": {
    "scripts": [
      "ExtPay.js",
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options.html"
  },
  "permissions": [
    "storage",
    "contextMenus",
    "https://powerwritingai.com/api/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://extensionpay.com/*"
      ],
      "js": [
        "ExtPay.js"
      ],
      "run_at": "document_start"
    },
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "ExtPay.js",
        "utils.js",
        "content.js"
      ]
    }
  ]
}