Examine source code of Search Engine Switcher

{
  "name": "Search Engine Switcher",
  "description": "When you are searching the net, press Alt+Shift+G to search at google, press Alt+Shift to search at duckduckgo.",
  "homepage_url": "https://gitlab.com/nils.dreier/search-engine-switcher",
  "manifest_version": 2,
  "version": "1.2resigned1",
  "permissions": [
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "commands": {
    "gotoGoogle": {
      "suggested_key": {
        "default": "Alt+Shift+G"
      },
      "description": "Switch to Google"
    },
    "gotoDuckDuckGo": {
      "suggested_key": {
        "default": "Alt+Shift+D"
      },
      "description": "Switch to DuckDuckGo"
    }
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e630208f-fdfc-4865-b895-8a94c4fbd1e0}"
    }
  }
}