Examine source code of Tab Volume 0-100

{
  "manifest_version": 2,
  "name": "Tab Volume",
  "version": "1.2.1",
  "description": "Adds volume control to your tabs.",
  "homepage_url": "https://github.com/mg2239/volume",
  "icons": {
    "96": "src/assets/icon.svg"
  },
  "browser_action": {
    "default_icon": "src/assets/icon.svg",
    "default_title": "Tab Volume",
    "default_popup": "src/index.html"
  },
  "background": {
    "scripts": [
      "src/background.js"
    ]
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a4086ef8-b463-40c9-af33-479645fd64f0}"
    }
  }
}