Examine source code of Purge Mask

{
  "name": "Purge Mask",
  "description": "Purge Mask Extension, A simple extension of mask choosing",
  "version": "0.0.0.5",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "permissions": [],
  "browser_action": {},
  "manifest_version": 2,
  "icons": {
    "128": "PurgeMask.png"
  }
}