Examine source code of MailTabs

{
  "manifest_version": 2,
  "name": "MailTabs",
  "version": "1.0.1",
  "description": "eMail the URLs of all the currently open browser tabs.",
  "icons": {
    "48": "icons/tabs-48.png"
  },
  "browser_action": {
    "default_icon": "icons/tabs-32.png",
    "theme_icons": [
      {
        "light": "icons/tabs-32-light.png",
        "dark": "icons/tabs-32.png",
        "size": 32
      }
    ],
    "default_title": "Mail Tabs",
    "default_popup": "popup/mailtabs.html"
  },
  "permissions": [
    "tabs",
    "storage"
  ]
}