Examine source code of user-agent-mac

{
  "description": "Change user-agent to Mac version",
  "manifest_version": 2,
  "name": "user-agent-mac",
  "version": "1.2resigned1",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{fbd5b808-2421-4640-9275-2c0dc4f18391}"
    }
  }
}