Examine source code of rainbowize

{
  "manifest_version": 2,
  "name": "rainbowize",
  "version": "1.0",
  "description": "Rainbowizes every link on websites",
  "icons": {
    "48": "icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "rainbowize.js"
      ]
    }
  ],
  "applications": {
    "gecko": {
      "id": "X@Y"
    }
  }
}