Examine source code of Smart Decoder

{
  "manifest_version" : 2 ,
  "name" : "Smart Decoder",
  "version" : "1.0",
  "description" : "Automatically detect and decode highlighted text",
  "permissions" : [
    "contextMenus" ,
    "activeTab" ,
    "clipboardWrite" 
  ],
  "background" : {
    "scripts" : [
      "background.js" 
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{25bb3169-91b8-4454-894c-7c6f3980f0bf}"
    }
  }
}