Examine source code of Smart Tab Mute

{
  "manifest_version": 2,
  "name": "Smart Tab Mute",
  "description": "Ensures that only one tab plays audio at the same time",
  "version": "1.0.1.2resigned1",
  "icons": {
    "16": "images/icon128.png",
    "48": "images/icon128.png",
    "128": "images/icon128.png"
  },
  "options_ui": {
    "page": "options.html",
    "chrome_style": true
  },
  "applications": {
    "gecko": {
      "id": "smart-tab-mute@die-antwort.eu",
      "strict_min_version": "47.0a1"
    }
  },
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "permissions": [
    "tabs",
    "storage"
  ]
}