Examine source code of Replace Maps

{
  "description": "Replace Google Maps iFrames with OpenStreetMap",
  "manifest_version": 2,
  "name": "Replace Maps",
  "version": "0.0.9",
  "homepage_url": "https://github.com/nobkd/replace-maps",
  "icons": {
    "48": "icons/48-icon.png",
    "96": "icons/96-icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "replace_maps@nobkd.github.io",
      "strict_min_version": "89.0"
    }
  },
  "permissions": [
    "tabs",
    "webNavigation",
    "storage",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "page": "bg.html"
  },
  "web_accessible_resources": [
    "map.html"
  ],
  "browser_action": {
    "default_icon": {
      "48": "icons/48-icon.png",
      "96": "icons/96-icon.png"
    },
    "default_area": "navbar",
    "default_title": "Replace Maps"
  },
  "options_ui": {
    "page": "options.html"
  }
}