Examine source code of Newsletterspot

{
  "manifest_version": 2,
  "name": "Newsletterspot",
  "version": "1.1resigned1",
  "description": "Curate Content to bookmark, share, build newsletters, blog.",
  "homepage_url": "https://newsletterspot.com",
  "icons": {
    "128": "icon.png"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "https://newsletterspot.com/is_logged_in/",
    "https://newsletterspot.com/add_item_to_db/",
    "https://newsletterspot.com/login/",
    "https://newsletterspot.com/get_all_latest_issues/"
  ],
  "background": {
    "scripts": [
      "event.js",
      "content.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "https://newsletterspot.com/is_logged_in/",
        "https://newsletterspot.com/add_item_to_db/",
        "https://newsletterspot.com/login/",
        "https://newsletterspot.com/get_all_latest_issues/"
      ],
      "js": [
        "popup.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_action": {
    "browser_style": true,
    "default_icon": "icon.png",
    "default_title": "Newsletterspot",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c0d28df2-627d-466f-a3c8-d3dbcceb0ea7}"
    }
  }
}