Examine source code of Booster 4 Volume

{
  "browser_specific_settings": {
    "gecko": {
      "id": "{05a62da0-a346-4c01-9a99-6b2582d40111}"
    }
  },
  "description": "Fix annoying sound problems in YouTube, Steam and any other sites that plays sound. Boost and control audio volume on any website beyond normal limits.",
  "icons": {
    "48": "icon.svg",
    "96": "icon.svg"
  },
  "name": "Sound Control",
  "version": "1.3.2",
  "manifest_version": 2,
  "browser_action": {
    "default_icon": "icon.svg",
    "theme_icons": [
      {
        "dark": "icon.svg",
        "light": "icon-inv.svg",
        "size": 64
      },
      {
        "dark": "icon.svg",
        "light": "icon-inv.svg",
        "size": 48
      },
      {
        "dark": "icon.svg",
        "light": "icon-inv.svg",
        "size": 32
      },
      {
        "dark": "icon.svg",
        "light": "icon-inv.svg",
        "size": 16
      }
    ],
    "default_popup": "popup.html",
    "default_title": "SoundFixer",
    "browser_style": true
  },
  "permissions": [
    "activeTab",
    "webNavigation",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ]
}