Examine source code of What Font

{
  "name": "What Font",
  "description": "__MSG_app_description__",
  "version": "1.0.2",
  "manifest_version": 2,
  "default_locale": "en",
  "permissions": [
    "storage",
    "tabs",
    "https://*.freebusinessapps.net/*",
    "notifications",
    "<all_urls>",
    "contextMenus",
    "clipboardWrite"
  ],
  "background": {
    "persistent": false,
    "scripts": [
      "common.js",
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "__MSG_browser_action__",
    "default_icon": {
      "16": "data/icons/16.png",
      "18": "data/icons/18.png",
      "19": "data/icons/19.png",
      "32": "data/icons/32.png",
      "36": "data/icons/36.png",
      "38": "data/icons/38.png",
      "48": "data/icons/48.png",
      "64": "data/icons/64.png",
      "128": "data/icons/128.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "data/inject/inject.js"
      ],
      "run_at": "document_start",
      "all_frames": true,
      "match_about_blank": true
    }
  ],
  "homepage_url": "https://findfont.freebusinessapps.net/",
  "icons": {
    "16": "data/icons/16.png",
    "18": "data/icons/18.png",
    "19": "data/icons/19.png",
    "32": "data/icons/32.png",
    "36": "data/icons/36.png",
    "38": "data/icons/38.png",
    "48": "data/icons/48.png",
    "64": "data/icons/64.png",
    "128": "data/icons/128.png"
  },
  "web_accessible_resources": [
    "data/inject/AND-Regular.otf",
    "data/window/index.html"
  ],
  "options_ui": {
    "page": "data/options/index.html",
    "chrome_style": true
  },
  "applications": {
    "gecko": {
      "id": "{3ab1d08e-5e80-4fa4-ae1a-d198a431755b}",
      "strict_min_version": "57.0"
    }
  }
}