Examine source code of Selective Mute

{
  "manifest_version": 2,
  "name": "Selective Mute",
  "version": "1.0.2resigned1",
  "applications": {
    "gecko": {
      "id": "selective.mute@selectivemute.com"
    }
  },
  "description": "Hides Facebook posts that contain user-defined keywords and/or phrases.",
  "icons": {
    "48": "icons/selmute-48.png",
    "96": "icons/selmute-96.png"
  },
  "browser_action": {
    "default_icon": "icons/selmute-38.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.facebook.com/*"
      ],
      "js": [
        "selmute.js"
      ]
    }
  ],
  "options_ui": {
    "page": "options.html"
  },
  "permissions": [
    "storage"
  ]
}