Examine source code of liberanews

{
  "manifest_version": 2,
  "name": "liberanews",
  "version": "0.0.16",
  "description": "liberanews",
  "icons": {
    "64": "icons/icon-64.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "browser-polyfill.js",
        "content_scripts.js"
      ]
    }
  ],
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "browser-polyfill.js",
      "background.js"
    ]
  },
  "web_accessible_resources": [
    "*.png",
    "*.svg"
  ]
}