Examine source code of Shmedium

{
  "manifest_version": 2,
  "name": "Shmedium",
  "version": "1.0",
  "description": "Shmedium is a Firefox extension that detects Medium paywall articles when navigating through Google Search and will flag them appropriately.",
  "icons": {
    "48": "icons/shmedium-icon-48.png",
    "128": "icons/shmedium-icon-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.google.com/*",
        "*://*.medium.com/*"
      ],
      "js": [
        "shmedium.js"
      ]
    }
  ],
  "permissions": [
    "storage",
    "webRequest",
    "webRequestBlocking",
    "webNavigation",
    "*://*.google.com/*",
    "*://*.medium.com/*",
    "*://localhost/*"
  ]
}