Examine source code of sonance

{
  "manifest_version": 2,
  "name": "sonance",
  "version": "1.1resigned1",
  "description": "Ambient sounds for your browser",
  "icons": {
    "48": "icons/sonance.png"
  },
  "browser_action": {
    "default_icon": "icons/sonance.png"
  },
  "background": {
    "scripts": [
      "index.js"
    ]
  },
  "web_accessible_resources": [
    "resources/*.mp3",
    "sonance/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9d7bbd33-de48-4bff-8122-af932c087b02}"
    }
  }
}