Examine source code of b64

{
  "manifest_version": 2,
  "name": "b64",
  "version": "0.2",
  "description": "Simple encoding and decoding of data in base64 format (only UTF-8 is supported) ",
  "icons": {
    "16": "img/icon_16.png",
    "32": "img/icon_32.png"
  },
  "browser_action": {
    "default_popup": "index.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "b64.js"
      ]
    }
  ]
}