Examine source code of Filter Affinity

{
  "manifest_version": 2,
  "name": "Filter Affinity",
  "short_name": "Filter Affinity",
  "description": "Filters out unwanted artists/images while browsing on Furaffinity.net",
  "version": "1.5.7",
  "icons": {
    "128": "128icon.png"
  },
  "permissions": [
    "notifications",
    "storage",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background-script.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": "128icon.png",
    "default_title": "Filter Affinity",
    "default_popup": "popup/popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.furaffinity.net/*"
      ],
      "run_at": "document_end",
      "js": [
        "content-script.js"
      ],
      "css": [
        "content-css.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "filter-affinity@mozilla.org"
    }
  }
}