Examine source code of Scrolly Marks

{
  "manifest_version": 2,
  "description": "Save your scroll position to a shortcut key so that you can jump around the page.",
  "name": "Scrolly Marks",
  "version": "1.0.2resigned1",
  "icons": {
    "48": "icons/scrolly-marks-48.png",
    "96": "icons/scrolly-marks-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "options_ui": {
    "page": "options.html"
  },
  "permissions": [
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "applications": {
    "gecko": {
      "id": "scrolly-marks@torology.com",
      "strict_min_version": "50.0"
    }
  }
}