Examine source code of Per-Element Audio Control

{
  "manifest_version": 2,
  "name": "Per-Element Audio Control",
  "version": "1.0.0",
  "description": "Automatically find audio/video elements on the page and add a per-element volume slider.",
  "permissions": [
    "storage",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "per-element-audio-control@example.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": [],
        "collects": false
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "web_accessible_resources": [
    "icons/*"
  ]
}