Examine source code of Scroll Persist

{
  "manifest_version": 2,
  "name": "Scroll Persist",
  "version": "1.0.0",
  "description": "A Firefox Extension to resume reading your favorite blog from where you left.",
  "icons": {
    "48": "icons/icon_48.png",
    "96": "icons/icon_96.png"
  },
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_start",
      "js": [
        "scrollpersist.js"
      ]
    }
  ]
}