Examine source code of FL Genius Loci

{
  "name": "FL Genius Loci",
  "description": "Play location-specific background music in \"Fallen London\"",
  "version": "1.2.2",
  "manifest_version": 2,
  "background": {
    "scripts": [
      "track_player.js",
      "background.js"
    ],
    "persistent": true
  },
  "permissions": [
    "tabs"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://www.fallenlondon.com/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_start"
    }
  ],
  "web_accessible_resources": [
    "tracks/*.mp3",
    "inject.js"
  ],
  "browser_action": {
    "default_icon": {
      "16": "/images/vinyl-icon-16.png",
      "32": "/images/vinyl-icon-32.png",
      "48": "/images/vinyl-icon-48.png",
      "128": "/images/vinyl-icon-128.png"
    },
    "default_title": "FL Genius Loci"
  },
  "icons": {
    "16": "/images/vinyl-icon-16.png",
    "32": "/images/vinyl-icon-32.png",
    "48": "/images/vinyl-icon-48.png",
    "128": "/images/vinyl-icon-128.png"
  }
}