Examine source code of Web EditorConfig

{
  "manifest_version" : 2 ,
  "name" : "Web EditorConfig",
  "description" : "Customize tab-width rendering on GitHub",
  "version" : "0.1.0",
  "icons" : {
    "16" : "icons/16.png",
    "32" : "icons/32.png",
    "48" : "icons/48.png",
    "128" : "icons/128.png"
  },
  "permissions" : [
    "storage" 
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "web-editorconfig@kjanat.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "browser_action" : {
    "default_title" : "Default Popup Title",
    "default_popup" : "popup.html"
  },
  "content_scripts" : [
    {
      "matches" : [
        "*://github.com/*" 
      ],
      "run_at" : "document_idle" ,
      "js" : [
        "content-scripts/content.js" 
      ]
    }
  ]
}