Examine source code of turn-around

{
  "manifest_version": 2,
  "name": "Boycott-er",
  "version": "1.0",
  "description": "Boycott shitty websites",
  "icons": {
    "48": "border-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "script.js"
      ]
    }
  ],
  "permissions": [
    "https://turn-around.glitch.me/list",
    "webRequest"
  ]
}