Examine source code of Sound Out

{
  "manifest_version": 2,
  "name": "Sound Out",
  "version": "1.6",
  "description": "Automatically mutes all tabs that are not currently active, except for user-defined sites.",
  "permissions": [
    "tabs",
    "storage",
    "contextMenus"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "icons": {
    "16": "icons/icon_on16.png",
    "32": "icons/icon_on32.png",
    "128": "icons/icon_on128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/icon_off16.png",
      "32": "icons/icon_off32.png"
    },
    "default_title": "Sound Out"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{92aad84d-7315-498a-8bac-6a8fae921ed6}"
    }
  }
}