Examine source code of Adjustable Audio Speed

{
  "manifest_version": 2,
  "name": "Adjustable Audio Speed",
  "version": "1.0",
  "description": "Slow down or speed up video/audio playback easily.",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Adjustable Audio Speed"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a95f1db9-b004-4b13-ac47-8eeae3a1764a}"
    }
  }
}