Examine source code of Outlook.com mailto

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "version": "2.7.1",
  "description": "__MSG_extensionDescription__",
  "author": "Wesley Branton",
  "default_locale": "en",
  "developer": {
    "name": "Wesley Branton",
    "url": "http://addons.wesleybranton.com"
  },
  "icons": {
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "96": "icons/icon-96.png"
  },
  "options_ui": {
    "page": "options/options.html",
    "browser_style": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "outlook@computerwhiz",
      "strict_min_version": "77.0"
    }
  },
  "protocol_handlers": [
    {
      "protocol": "mailto",
      "name": "Outlook.com",
      "uriTemplate": "https://outlook.com/send/?to=%s"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "storage",
    "menus",
    "tabs",
    "webRequest",
    "webRequestBlocking",
    "*://outlook.com/send/*"
  ],
  "optional_permissions": [
    "<all_urls>"
  ]
}