Examine source code of Itch.io Genre Filter

{
  "manifest_version": 2,
  "name": "Itch.io Genre Filter",
  "version": "1.0",
  "description": "Automatically hide games on Itch.io based on genre, UI appears when toolbar icon is clicked.",
  "permissions": [
    "storage",
    "activeTab"
  ],
  "browser_action": {
    "default_title": "Itch.io Genre Filter"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://itch.io/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{83dc6940-bc38-48b3-86a1-c4d3332bf6f2}"
    }
  }
}