chrome/common/extensions/docs/examples/api/input.ime/basic/manifest.json

{
  "name": "Test IME",
  "version": "1.0",
  "manifest_version": 2,
  "description": "A simple IME that converts all keystrokes to upper case.",
  "background":  {
    "scripts": ["main.js"]
  },
  "permissions": [
    "input"
  ],
  "input_components": [
    {
      "name": "Test IME",
      "type": "ime",
      "id": "test",
      "description": "Test IME",  // A user visible description
      "language": "en-US",  // The primary language this IME is used for
      "layouts": ["us::eng"]  // The supported keyboard layouts for this IME
    }
  ]
}