Examine source code of Breached

{
  "name": "Breached",
  "version": "1.2.5resigned1",
  "manifest_version": 2,
  "description": "Find out which sites you're visiting have been pwned, using the haveibeenpwned.com database",
  "homepage_url": "https://github.com/adam-p/breached",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png",
    "256": "icons/icon256.png"
  },
  "background": {
    "scripts": [
      "vendor/jquery-3.2.1.min.js",
      "src/bg/background.js"
    ],
    "persistent": false
  },
  "page_action": {
    "browser_style": true,
    "default_icon": {
      "16": "icons/icon16.png",
      "19": "icons/icon19.png",
      "32": "icons/icon32.png",
      "38": "icons/icon38.png",
      "48": "icons/icon48.png",
      "64": "icons/icon64.png"
    },
    "default_title": "Breached! Click for details",
    "default_popup": "src/page_action/page_action.html"
  },
  "permissions": [
    "storage",
    "tabs",
    "notifications"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{39672041-6f70-4b27-b5ee-c2febd92e0c4}"
    }
  }
}