Examine source code of Extract Source URL

{
  "manifest_version": 2,
  "name": "Extract Source URL",
  "version": "1.0",
  "description": "Right-click on any element with a src attribute to extract its source URL",
  "browser_specific_settings": {
    "gecko": {
      "id": "extract-source-url@yourdomain.com",
      "strict_min_version": "58.0"
    }
  },
  "permissions": [
    "contextMenus",
    "clipboardWrite",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "icons": {
    "16": "icon16.svg"
  }
}