Examine source code of MailLinkTo Extension

{
  "manifest_version": 2,
  "name": "MailLinkTo Extension",
  "version": "0.4",
  "permissions": [
    "activeTab",
    "tabs",
    "scripting"
  ],
  "summary": "A simple extension to email the tab url using the default mail app",
  "description": "MailLinkTo is a simple extension that open a mailto: href with the tab title as the subject and the href as the body.  It exists because the prior extensions have been de-listed, probably because they became malicious.   I just want this for my own use, really (lol).",
  "icons": {
    "16": "images/mail-16.png",
    "48": "images/mail-48.png",
    "96": "images/mail-96.png"
  },
  "background": {
    "scripts": [
      "firefox-background.js"
    ]
  },
  "browser_action": {
    "default_icon": "images/mail-32.png",
    "theme_icons": [
      {
        "light": "images/mail-32.png",
        "dark": "images/mail-32.png",
        "size": 32
      }
    ],
    "default_title": "MailLinkTo"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{55b93fac-aa24-487a-a036-4b683ea96a6a}"
    }
  }
}