Examine source code of Blue Text Extension

{
  "manifest_version": 2,
  "name": "Blue Text Extension",
  "version": "1.0",
  "description": "Displays blue text on the top left corner of the screen",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d6f792bb-2e3b-4fd3-b664-10b738e9d275}"
    }
  }
}