mail/gmail-test-proxy/manifest.json

{
  "name": "IMAP Test",
  "description": "Testing chrome.socket for IMAP",
  "version": "0.0.1",
  "manifest_version": 2,
  "offline_enabled": true,
  "permissions": [{
    "socket": ["tcp-connect"]
  }],
  "app": {
    "background": {
      "scripts": ["background.js"]
    }
  }
}