Examine source code of Wallpaper Tab

{
  "manifest_version": 2,
  "name": "Wallpaper Tab",
  "version": "1.6.0",
  "description": "Replaces the background of new tabs with a daily changing image.",
  "chrome_url_overrides": {
    "newtab": "newtab/newtab.html"
  },
  "browser_action": {
    "default_title": "Wallpaper Tab Settings",
    "default_icon": "icons/icon-48.png"
  },
  "options_ui": {
    "page": "settings/settings.html",
    "open_in_tab": true
  },
  "background": {
    "scripts": [
      "background/background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "storage",
    "topSites",
    "https://api.flickr.com/*",
    "https://live.staticflickr.com/*",
    "https://img.peapix.com/*",
    "https://peapix.com/*",
    "https://lh3.googleusercontent.com/*",
    "https://en.wikiquote.org/*",
    "browserSettings",
    "https://api.nasa.gov/*",
    "https://apod.nasa.gov/*",
    "https://collectionapi.metmuseum.org/*",
    "https://images.metmuseum.org/*",
    "https://en.wikipedia.org/*",
    "https://commons.wikimedia.org/*",
    "https://upload.wikimedia.org/*"
  ],
  "icons": {
    "48": "icons/icon-48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "wallpaper-tab@local",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  },
  "chrome_settings_overrides": {
    "homepage": "newtab/newtab.html"
  }
}