Examine source code of Tab Switcher Sound

{
  "manifest_version": 2,
  "name": "Tab Switcher Sound",
  "version": "1.0",
  "description": "Plays a short whoosh or instrument sound when you switch tabs.",
  "permissions": [
    "tabs",
    "storage",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{50b7bb30-1167-4f54-addc-798d7f56716f}"
    }
  }
}