Examine source code of Aqua Volume Booster

{
  "manifest_version": 2,
  "name": "Aqua Volume Booster",
  "short_name": "Aqua Volume",
  "version": "1.0.0",
  "author": "Aqua Project",
  "description": "Lautstärkeverstärker bis 1500 %, 10-Band-Equalizer, Limiter und Stereowerkzeuge — pro Seite gespeichert.",
  "browser_specific_settings": {
    "gecko": {
      "id": "volume-booster@aqua-browser",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "48": "icons/icon.svg",
    "96": "icons/icon.svg"
  },
  "permissions": [
    "storage",
    "tabs",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "common/defaults.js",
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "common/defaults.js",
        "content/booster.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ],
  "browser_action": {
    "default_title": "Aqua Volume Booster",
    "default_icon": "icons/icon.svg",
    "default_popup": "popup/popup.html"
  },
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": true
  },
  "commands": {
    "volume-up": {
      "suggested_key": {
        "default": "Alt+Shift+Up"
      },
      "description": "Lautstärke erhöhen"
    },
    "volume-down": {
      "suggested_key": {
        "default": "Alt+Shift+Down"
      },
      "description": "Lautstärke senken"
    },
    "volume-reset": {
      "suggested_key": {
        "default": "Alt+Shift+0"
      },
      "description": "Auf 100 % zurücksetzen"
    },
    "toggle-boost": {
      "suggested_key": {
        "default": "Alt+Shift+B"
      },
      "description": "Booster für diese Seite an/aus"
    }
  }
}