Examine source code of Soundgasm View Counter

{
  "description": "Adds a view counter to Soundgasm user pages, showing the number of views for all sounds combined.",
  "manifest_version": 2,
  "name": "Soundgasm View Counter",
  "version": "1.0",
  "homepage_url": "https://github.com/mdn/webextensions-examples/tree/master/borderify",
  "icons": {
    "48": "icons/spiral-icon_48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://soundgasm.net/u/*"
      ],
      "js": [
        "viewCounter.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d95d48ed-773b-4b65-b157-769ed315c4f0}"
    }
  }
}