Examine source code of SoundDirection

{
  "manifest_version": 2,
  "name": "SoundDirection",
  "version": "1.0.0",
  "description": "Show stereo direction (L-R balance) of audio playing in the tab as a small clock-like dial.",
  "permissions": [
    "storage",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "sound-direction@example.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "collects": false
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "web_accessible_resources": [
    "icons/*"
  ],
  "browser_action": {
    "default_title": "SoundDirection",
    "default_popup": "popup.html"
  }
}