Examine source code of Shush!

{
  "manifest_version": 2,
  "name": "Shush!",
  "short_name": "shush",
  "description": "An addon to mute a list of words on several website like Twitter, Facebook or Linkedin",
  "homepage_url": "https://github.com/adriantombu/shush",
  "version": "1.2.3",
  "author": "Adrian Tombu",
  "icons": {
    "48": "assets/icon-48.png",
    "96": "assets/icon-96.png",
    "128": "assets/icon-128.png"
  },
  "browser_action": {
    "default_icon": {
      "48": "assets/icon-48.png",
      "96": "assets/icon-96.png"
    },
    "default_title": "Shush! parameters",
    "default_popup": "index.html"
  },
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.twitter.com/*",
        "*://*.facebook.com/*",
        "*://*.linkedin.com/*",
        "*://*.lemonde.fr/*",
        "*://*.liberation.fr/*",
        "*://*.lesechos.fr/*",
        "*://*.lci.fr/*",
        "*://*.lopinion.fr/*",
        "*://*.lefigaro.fr/*",
        "*://*.20minutes.fr/*",
        "*://*.leparisien.fr/*",
        "*://*.humanite.fr/*",
        "*://*.latribune.fr/*",
        "*://*.francesoir.fr/*",
        "*://*.lequipe.fr/*",
        "*://*.eurosport.fr/*",
        "*://*.rugbyrama.fr/*",
        "*://*.dhnet.be/*",
        "*://*.lalibre.be/*",
        "*://*.nytimes.com/*"
      ],
      "js": [
        "app.js"
      ],
      "css": [
        "styles.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{1bdaddc2-e83b-4cf6-8aa4-e313e4937a9b}"
    }
  }
}