Examine source code of Typing Speed Test

{
  "manifest_version": 2,
  "name": "Typing Speed Test",
  "description": "Measure your typing speed and accuracy on varied texts. Live WPM counter, per-character highlighting and personal best.",
  "version": "2.7",
  "browser_specific_settings": {
    "gecko": {
      "id": "{582a115a-ed0b-41e1-a2bb-3c7832964d35}",
      "strict_min_version": "101.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "32": "graphics/icon-32.png",
    "48": "graphics/icon-48.png",
    "64": "graphics/icon-64.png",
    "96": "graphics/icon-96.png",
    "128": "graphics/icon-128.png"
  },
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_title": "Typing Speed Test",
    "default_popup": "core/popup.html",
    "default_icon": {
      "32": "graphics/icon-32.png",
      "48": "graphics/icon-48.png",
      "64": "graphics/icon-64.png",
      "96": "graphics/icon-96.png",
      "128": "graphics/icon-128.png"
    }
  }
}