Examine source code of Delete Facebook Messages

{
  "manifest_version": 2,
  "name": "__MSG_appName__",
  "description": "__MSG_appDescription__",
  "version": "0.0.5",
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "default_locale": "en",
  "permissions": [
    "storage"
  ],
  "web_accessible_resources": [
    "images/*",
    "content-scripts/content.css"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ae237f87-80c1-4281-8ecf-8b619bd7b518}",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Popup",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.facebook.com/messages/*"
      ],
      "js": [
        "content-scripts/content.js"
      ]
    }
  ]
}