Examine source code of Subfilter for Netflix

{
  "manifest_version": 3,
  "name": "Subfilter for Netflix",
  "description": "Watch your favourite series on Netflix with filtered subtitles and improve foreign language at the same time.",
  "version": "0.5.2",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.netflix.com/*"
      ],
      "run_at": "document_end",
      "js": [
        "content_script.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "matches": [
        "https://www.netflix.com/*"
      ],
      "resources": [
        "content.js",
        "filters.js",
        "custom_filters.js",
        "subfilter-ui.js",
        "style.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{7da1e026-3a0c-4268-8717-67f702258ea0}"
    }
  }
}