Examine source code of Copy Source URL

{
  "manifest_version": 2,
  "name": "Copy Source URL",
  "description": "Append source url to text on copy",
  "version": "1.0.0",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "content-scripts/content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{85ae438e-07c1-4409-9a14-83f56c201d7d}"
    }
  }
}