Examine source code of Feedly Open All Unread

{
  "manifest_version": 2,
  "name": "Feedly Open All Unread",
  "version": "1.5.4",
  "description": "Adds a button to feedly.com to open all unread articles in new tabs",
  "homepage_url": "https://github.com/cypressious/ff-feedly-open-unread",
  "content_scripts": [
    {
      "matches": [
        "*://feedly.com/*"
      ],
      "js": [
        "browser-polyfill.min.js",
        "content-script.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "browser-polyfill.min.js",
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options.html"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{aa2dedd6-d243-4d9c-bcf2-0e2ab3812a4e}"
    }
  }
}