Examine source code of SoundFox

{
  "manifest_version": 3,
  "name": "SoundFox",
  "version": "1.5.0",
  "description": "Sound booster & master for your browser.",
  "browser_specific_settings": {
    "gecko": {
      "id": "soundfox@vadimcastro.github.io",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  },
  "action": {
    "default_popup": "index.html",
    "default_icon": {
      "16": "icon-16.png",
      "48": "icon-48.png",
      "128": "icon-128.png"
    }
  },
  "icons": {
    "16": "icon-16.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "commands": {
    "preset-0": {
      "suggested_key": {
        "default": "Ctrl+Shift+0"
      },
      "description": "Set volume to 0% (mute)"
    },
    "preset-50": {
      "suggested_key": {
        "default": "Ctrl+Shift+9"
      },
      "description": "Set volume to 50%"
    },
    "preset-100": {
      "suggested_key": {
        "default": "Ctrl+Shift+1"
      },
      "description": "Set volume to 100%"
    },
    "preset-200": {
      "suggested_key": {
        "default": "Ctrl+Shift+2"
      },
      "description": "Set volume to 200%"
    },
    "preset-300": {
      "suggested_key": {
        "default": "Ctrl+Shift+3"
      },
      "description": "Set volume to 300%"
    },
    "preset-400": {
      "suggested_key": {
        "default": "Ctrl+Shift+4"
      },
      "description": "Set volume to 400%"
    },
    "preset-500": {
      "suggested_key": {
        "default": "Ctrl+Shift+5"
      },
      "description": "Set volume to 500%"
    },
    "preset-600": {
      "suggested_key": {
        "default": "Ctrl+Shift+6"
      },
      "description": "Set volume to 600%"
    }
  },
  "permissions": [
    "activeTab",
    "scripting",
    "tabs",
    "storage"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "src/background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "all_frames": true,
      "match_about_blank": true,
      "js": [
        "src/content.js"
      ]
    }
  ]
}