Examine source code of Reviewer

{
  "manifest_version": 2,
  "name": "Reviewer",
  "version": "1.0.1",
  "description": "Displays a percentage value next to the review of any selected Google Maps Place. This value is calculated based on 3Blue1Brown's video on comparing review scores: https://youtu.be/8idr1WZ1A7Q",
  "icons": {
    "48": "icons/reviewer_logo_48.png",
    "96": "icons/reviewer_logo_96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.google.com/maps/place/*"
      ],
      "js": [
        "reviewer.js",
        "purify.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "reviewer_background.js"
    ]
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "options_ui": {
    "page": "options.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d2332c0e-9a86-4315-ba5b-1601ed49f0fd}"
    }
  }
}