Examine source code of MailPlus Alias

{
  "manifest_version": 2,
  "name": "MailPlus Alias",
  "version": "1.0.1",
  "description": "Allows to create mail alias for Synology MailPlus Server directly from the browser, like the Firefox Relay extension but with your own domain(s).",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "storage",
    "<all_urls>",
    "contextMenus",
    "menus"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "MailPlus Alias",
    "default_popup": "popup/popup.html"
  },
  "background": {
    "page": "background.html"
  },
  "developer": {
    "name": "Sosthèn Gaillard",
    "url": "https://github.com/SosthenG"
  }
}