Examine source code of Book club roulette

{
  "manifest_version": 2,
  "name": "Book club roulette",
  "version": "1.0",
  "description": "Allow us to download the current Google spreadsheets as a CSV. To latter display a roulette to choose a random selection. Intended for a book club. It does not save nor modify any data from Google Spreadsheets, it only reads it to display it.",
  "icons": {
    "19": "icon_19.jpeg",
    "38": "icon_38.jpeg"
  },
  "page_action": {
    "browser_style": true,
    "default_title": "Book club roulette",
    "default_popup": "./popup/index.html",
    "default_icon": {
      "19": "icon_19.jpeg",
      "38": "icon_38.jpeg"
    },
    "show_matches": [
      "https://docs.google.com/spreadsheets/**"
    ]
  },
  "permissions": [
    "activeTab",
    "https://docs.google.com/spreadsheets/**"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "vx_bookclubextension@jvega.com"
    }
  }
}