Examine source code of Inbox Mailer

{
  "manifest_version": 2,
  "name": "Inbox Mailer",
  "version": "1.2",
  "description": "Send Email to configured address",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_action": {
    "default_icon": {
      "48": "icon-48.png",
      "512": "icon.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{c531e4c3-9c66-4d42-89f8-7b1d884f8216}"
    }
  }
}