Examine source code of Padlet Mini

{
  "manifest_version": 2,
  "name": "Padlet Mini",
  "description": "__MSG_extDescription__",
  "version": "5.1.6",
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "default_locale": "en",
  "options_page": "options.html",
  "permissions": [
    "activeTab",
    "contextMenus",
    "storage",
    "tabs",
    "https://pepin.padlet.com/*"
  ],
  "web_accessible_resources": [
    "icons/16.png"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "open_in_tab": true,
    "page": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.padlet.com/add-post*",
        "*://*.padlet.org/add-post*"
      ],
      "run_at": "document_start",
      "js": [
        "content-scripts/addpost.js"
      ]
    }
  ],
  "browser_action": {
    "default_title": "Add page to Padlet"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ac23cba8-8e2e-4a64-b4b4-9db87249c38b}"
    }
  }
}