Examine source code of Quick Switch

{
  "manifest_version": 2,
  "name": "Quick Switch",
  "version": "1.1",
  "description": "Quickly switch between two different tabs",
  "commands": {
    "toggle-feature": {
      "suggested_key": {
        "default": "Ctrl+Q"
      },
      "description": "Send a 'toggle-feature' event"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "activeTab"
  ],
  "icons": {
    "32": "icons/recycable_32.png",
    "64": "icons/recycable_64.png"
  }
}