Examine source code of Focus Sound Background

{
  "manifest_version": 2,
  "name": "Focus Sound Background",
  "version": "1.0",
  "description": "Play soft background music while browsing.",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Focus Sound Background"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7e4e314a-3cc1-44a3-a3e5-84a6a2cefcae}"
    }
  }
}