Examine source code of Less Simple link preview

{
  "manifest_version": 2,
  "name": "Less Simple link preview",
  "version": "1",
  "description": "Preview links without leaving your current page by clicking on an icon.",
  "icons": {
    "64": "images/logo_big.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "link_preview.js"
      ],
      "css": [
        "link_preview.css"
      ]
    }
  ],
  "background": {
    "scripts": [
      "ignore-frame-options.js"
    ]
  },
  "web_accessible_resources": [
    "images/*.png",
    "images/*.svg"
  ],
  "permissions": [
    "storage",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ddeafeef-3ae2-4c16-9f22-6226b1c99fbb}"
    }
  }
}